Free 120 Step 2 CK Block 2 covers items 41–80 of the official USMLE Step 2 CK practice set. This page gives you the answer key for all 40 items, then a full explanation of each one: the reasoning that leads to the correct answer, why every distractor is wrong, and the educational objective the item is testing. Work through the official booklet first, then read these explanations alongside it.
Recall Mastery is not affiliated with the NBME, FSMB or the USMLE program. The official USMLE Step 2 CK Sample Test Questions booklet is available free from usmle.org. The questions are not reproduced here — these are our own explanations, written to be read alongside the official booklet. Item, block and page numbers match the July 2023 edition.
What Block 2 actually tests
Block 2 of the Free 120 covers items 41–80. Here is how those 40 questions break down by subject — useful for spotting which systems cost you the most marks:
| System | Items in this block |
|---|---|
| Obstetrics & Gynecology | 6 |
| Infectious Disease | 3 |
| Renal | 3 |
| Cardiovascular | 3 |
| Heme/Onc | 3 |
| Endocrine | 3 |
| Musculoskeletal | 3 |
| Dermatology | 3 |
| Gastrointestinal | 3 |
| Ethics | 3 |
| Biostatistics & Prevention | 2 |
| Respiratory | 2 |
| Psychiatry | 1 |
| Neurology | 1 |
| Geriatrics | 1 |
Answer key — Free 120 Step 2 CK Block 2 (items 41–80)
Score yourself first, then read the explanation for anything you missed or guessed.
| Item | Answer | System |
|---|---|---|
| Item 41 | D — HIV RNA polymerase chain reaction testing | Infectious Disease |
| Item 42 | A — Acute kidney injury | Renal |
| Item 43 | C — Lithium | Psychiatry |
| Item 44 | E — Preterm labor | Obstetrics & Gynecology |
| Item 45 | B — Clonidine | Cardiovascular |
| Item 46 | C — Serum lipid studies | Biostatistics & Prevention |
| Item 47 | A — Review for potential drug-drug interaction | Heme/Onc |
| Item 48 | A — Glucose Increased, Insulin increased, Insulin Receptor Responsiveness decreased | Endocrine |
| Item 49 | C — Adverse effect of trimethoprim-sulfamethoxazole | Heme/Onc |
| Item 50 | C — Knee No diagnostic testing indicated, Ankle x-ray | Musculoskeletal |
| Item 51 | C — X-rays of the left hand and wrist | Endocrine |
| Item 52 | A — Corticosteroid injection | Dermatology |
| Item 53 | F — Tube thoracostomy | Respiratory |
| Item 54 | E — Giardia lamblia | Infectious Disease |
| Item 55 | B — 2.6 | Biostatistics & Prevention |
| Item 56 | E — Esophagogastroduodenoscopy | Gastrointestinal |
| Item 57 | D — Endoscopic hemostatic therapy | Gastrointestinal |
| Item 58 | F — Biopsy of the vulva | Obstetrics & Gynecology |
| Item 59 | D — Spinal stenosis | Musculoskeletal |
| Item 60 | D — Measurement of urine and plasma osmolarity | Renal |
| Item 61 | D — Provide palliative therapy only | Ethics |
| Item 62 | E — Penicillin prophylaxis | Heme/Onc |
| Item 63 | B — Levothyroxine therapy | Endocrine |
| Item 64 | C — CT scan of the abdomen | Gastrointestinal |
| Item 65 | E — Transabdominal ultrasonography | Obstetrics & Gynecology |
| Item 66 | A — tell the son the decision belongs to the patient | Ethics |
| Item 67 | C — Small vessel disease | Neurology |
| Item 68 | D — Type of vaginal discharge | Obstetrics & Gynecology |
| Item 69 | B — Gout | Musculoskeletal |
| Item 70 | C — Coronary artery disease | Cardiovascular |
| Item 71 | C — Excessive alcohol use | Cardiovascular |
| Item 72 | C — Kaposi sarcoma | Dermatology |
| Item 73 | A — Measurement of serum follicle-stimulating hormone concentration | Obstetrics & Gynecology |
| Item 74 | E — report to the clinic administrator and cover the rest of the clinic without him | Ethics |
| Item 75 | E — No additional testing is indicated | Renal |
| Item 76 | D — Surgical debridement | Dermatology |
| Item 77 | C — Fasting glucose tolerance test | Obstetrics & Gynecology |
| Item 78 | B — Elder neglect | Geriatrics |
| Item 79 | B — serum Borrelia burgdorferi antibody testing | Infectious Disease |
| Item 80 | D — Nebulized epinephrine | Respiratory |
Free 120 Step 2 CK Block 2 explanations: items 41–80
Item 41 — HIV RNA polymerase chain reaction testing [Infectious Disease]
Answer: D — HIV RNA polymerase chain reaction testing
A mononucleosis-like febrile illness after potential sexual exposure, with leukopenia and marked lymphopenia, is acute HIV infection. During this early viremic phase, fever, myalgias, fatigue, and pharyngitis may occur before HIV antibodies become detectable.
HIV RNA testing detects circulating virus during the diagnostic window period and is therefore the appropriate next test when acute retroviral syndrome is suspected. A negative antibody-based test at this stage would not exclude infection.
- A) Cytomegalovirus can cause heterophile-negative mononucleosis, but it typically produces lymphocytosis with atypical lymphocytes rather than marked lymphopenia.
- B) Epstein-Barr virus serology is useful when early infectious mononucleosis is suspected despite a negative Monospot. This patient lacks lymphadenopathy, splenomegaly, and atypical lymphocytosis.
- C) Hemagglutination inhibition assays assess influenza-specific antibodies and are not the appropriate diagnostic test for this acute presentation; vaccination also complicates serologic interpretation.
- E) Hepatitis B surface antigen detects active HBV infection, which more often produces hepatitis-related findings rather than an isolated mononucleosis-like syndrome with lymphopenia.
Educational objective: When a patient develops fever, myalgias, fatigue, and pharyngitis shortly after a potential sexual exposure, especially with leukopenia or lymphopenia, think acute retroviral syndrome. Detect early infection with HIV RNA or p24 antigen because antibody tests may still be negative.
Item 42 — Acute kidney injury [Renal]
Answer: A — Acute kidney injury
Profound creatine kinase elevation after prolonged opioid-induced unconsciousness indicates rhabdomyolysis, placing him at high risk for myoglobin-induced acute kidney injury. Prolonged immobilization and the cold, cyanotic limb suggest sustained muscle compression and ischemia, explaining the CK of 50,000 U/L, hyperkalemia, and metabolic acidosis.
Released myoglobin causes intrarenal vasoconstriction, direct proximal tubular toxicity, and distal tubular obstruction after precipitation with uromodulin, particularly in acidic urine. His creatinine is still normal because he has presented early; serum creatinine lags behind the acute fall in GFR.
- B) Acute liver failure may follow severe hypoxic or toxic injury, but there is no evidence of hepatic dysfunction. The dominant organ threat from massive muscle breakdown is pigment nephropathy.
- C) Cardiac arrhythmia can occur with severe hyperkalemia, but potassium is only mildly elevated at 5.5 mEq/L. Ongoing rhabdomyolysis primarily threatens renal function.
- D) Hypocalcemia can occur early in rhabdomyolysis as calcium deposits in damaged muscle, but it is a metabolic complication rather than the major organ failure anticipated here.
- E) Hypophosphatemia can precipitate rhabdomyolysis; established muscle breakdown instead releases intracellular phosphate and may produce hyperphosphatemia.
Educational objective: When prolonged unconsciousness or limb compression is followed by a markedly elevated CK, think rhabdomyolysis with impending myoglobin-induced acute tubular injury. A normal initial creatinine does not exclude evolving AKI.
Item 43 — Lithium [Psychiatry]
Answer: C — Lithium
Confusion, seizure, and second-degree AV block after prolonged activity in warm weather indicate lithium toxicity precipitated by dehydration. Lithium has a narrow therapeutic index and is eliminated almost entirely by the kidneys. Volume and sodium depletion from sweating increase renal lithium reabsorption, raising serum and tissue concentrations even without a dosage change.
Neurologic toxicity progresses from tremor, ataxia, and confusion to delirium, seizures, and coma. Cardiac toxicity includes sinus node dysfunction, arrhythmias, and atrioventricular conduction block. Her age further increases vulnerability because lithium clearance declines with renal reserve.
- A) Acetaminophen toxicity causes hepatic injury and may produce encephalopathy in fulminant liver failure, but it does not explain dehydration-associated AV block and seizures after therapeutic as-needed use.
- B) Bupropion lowers the seizure threshold, especially in overdose, but it is not a standard long-term mood stabilizer and does not fit the volume-depletion trigger or characteristic conduction toxicity.
- D) Risperidone can cause sedation, extrapyramidal effects, hyperprolactinemia, and QT prolongation. Lithium better unifies the neurologic deterioration and AV block following dehydration.
- E) Topiramate can cause cognitive slowing, metabolic acidosis, nephrolithiasis, and impaired sweating. The combination of severe encephalopathy, seizure, and AV conduction block is more characteristic of lithium toxicity.
Educational objective: When a patient taking long-term therapy for bipolar disorder develops confusion, seizures, or conduction abnormalities after sweating, dehydration, or sodium depletion, think lithium toxicity. Volume depletion increases renal lithium reabsorption.
Item 44 — Preterm labor [Obstetrics & Gynecology]
Answer: E — Preterm labor
The hysterosalpingogram shows a congenital Müllerian uterine anomaly with two divergent uterine horns, consistent with a bicornuate uterus. Her unilateral renal agenesis strengthens the diagnosis because urinary and Müllerian tract anomalies commonly coexist due to their closely linked embryologic development.
Abnormal uterine architecture reduces effective cavity volume and impairs normal uterine distension during pregnancy, increasing the risk of preterm labor and delivery. Other important obstetric associations include miscarriage and fetal malpresentation.
- A) Fetal macrosomia is associated with maternal diabetes, excessive gestational weight gain, and post-term pregnancy, not Müllerian anomalies.
- B) Multiple gestation is primarily associated with assisted reproductive technology, ovulation induction, and familial dizygotic twinning.
- C) Oligohydramnios is linked to ruptured membranes, uteroplacental insufficiency, or fetal renal/urinary tract abnormalities. Maternal unilateral renal agenesis does not itself imply reduced fetal urine production.
- D) Preeclampsia risk rises with chronic hypertension, renal disease, diabetes, and multifetal gestation. It is not the principal obstetric complication of this uterine anomaly.
Educational objective: When hysterosalpingography shows a congenital uterine anomaly—especially with an associated renal anomaly—remember the major pregnancy risks: preterm labor, miscarriage, and malpresentation.
Item 45 — Clonidine [Cardiovascular]
Answer: B — Clonidine
A 20-mm Hg systolic blood pressure drop after standing, with light-headedness, tunnel vision, and near-syncope, indicates orthostatic hypotension. The culprit is clonidine, started 10 days before symptom onset.
Clonidine is a central α2-adrenergic agonist that reduces sympathetic outflow. The resulting decrease in vascular tone can cause hypotension, while reduced cardiac sympathetic activity may produce bradycardia and lethargy. The temporal relationship and documented postural blood pressure fall make clonidine the best explanation.
- A) Albuterol commonly causes tremor, palpitations, and tachycardia through β2-adrenergic stimulation, not orthostatic hypotension.
- C) Methylphenidate increases catecholaminergic activity and more often raises heart rate and blood pressure. She has also used it before the current symptoms began.
- D) Prednisone can cause hyperglycemia, mood changes, fluid retention, and hypertension. A brief course does not explain this postural blood pressure fall.
- E) Rifampin commonly causes orange discoloration of body fluids, hepatotoxicity, and drug interactions; it does not fit isolated orthostatic hypotension without systemic illness.
Educational objective: When near-syncope begins soon after clonidine initiation and blood pressure falls on standing, think clonidine-induced orthostatic hypotension. Central α2 agonism lowers sympathetic outflow, producing hypotension, bradycardia, and lethargy.
Item 46 — Serum lipid studies [Biostatistics & Prevention]
Answer: C — Serum lipid studies
Absent pedal pulses plus a femoral bruit in a former smoker indicates lower-extremity atherosclerotic peripheral artery disease. She is asymptomatic, so the priority is cardiovascular risk assessment and modification—not symptom-directed medication or invasive arterial imaging.
A lipid profile identifies a major modifiable atherosclerotic risk factor and guides lipid-lowering therapy. PAD is a marker of systemic atherosclerosis and increased coronary and cerebrovascular risk, even when collateral circulation prevents claudication. If offered, the ankle-brachial index would be the appropriate noninvasive test to confirm and quantify PAD; catheter angiography is unnecessary without planned revascularization.
- A) Pentoxifylline is intended to improve walking symptoms in intermittent claudication. She has no exertional limb symptoms requiring pharmacologic symptom relief.
- B) Peripheral artery catheterization defines vascular anatomy before endovascular or surgical revascularization. It is not routine diagnostic testing in asymptomatic PAD.
- D) Warfarin is used for selected thromboembolic conditions, not routine atherosclerotic PAD, and adds substantial bleeding risk.
- E) Asymptomatic PAD still requires evaluation and aggressive modification of atherosclerotic risk factors; absence of claudication does not make it benign.
Educational objective: When absent distal pulses and an arterial bruit suggest PAD, assess and treat systemic cardiovascular risk factors. Reserve angiography for patients being considered for revascularization.
Item 47 — Review for potential drug-drug interaction [Heme/Onc]
Answer: A — Review for potential drug-drug interaction
Starting trimethoprim-sulfamethoxazole in a patient taking warfarin caused the abrupt INR elevation to 5.2. TMP-SMX inhibits warfarin metabolism, potentiating anticoagulation and increasing bleeding risk. A medication reconciliation with drug-interaction review before prescribing the antibiotic would have identified this preventable hazard.
This is a near miss because the patient has excessive anticoagulation without bleeding yet. For an asymptomatic INR between 3.5 and 10, warfarin is withheld until the INR returns to the therapeutic range; vitamin K is generally reserved for INR >10 or clinically significant bleeding.
- B) Dietary counseling helps maintain consistent vitamin K intake during warfarin therapy, but the temporal trigger here is initiation of TMP-SMX three days earlier.
- C) Echocardiography evaluates prosthetic valve function and cardiac structure. The mechanical click and lack of cardiopulmonary symptoms provide no explanation for the supratherapeutic INR.
- D) Venous duplex ultrasonography evaluates suspected deep venous thrombosis. Warm erythema improving with antibiotics and intact pulses do not explain the coagulation abnormality.
- E) Allopurinol is not the newly introduced medication responsible for this abrupt INR increase; discontinuing chronic gout therapy would not prevent the TMP-SMX–warfarin interaction.
Educational objective: When a stable warfarin patient develops a sudden INR elevation after starting a new medication, think drug-drug interaction first. TMP-SMX inhibits warfarin metabolism and can produce dangerous over-anticoagulation.
Item 48 — Glucose Increased, Insulin increased, Insulin Receptor Responsiveness decreased [Endocrine]
Answer: A — Glucose Increased, Insulin increased, Insulin Receptor Responsiveness decreased
In type 2 diabetes, the primary defect is reduced responsiveness of target tissues to insulin. Impaired post-receptor insulin signaling in skeletal muscle, liver, and adipose tissue means that a normal amount of insulin produces a subnormal effect, so insulin receptor responsiveness is decreased.
Pancreatic β cells compensate by secreting more insulin, so the circulating insulin concentration is increased. The compensation is incomplete: hepatic glucose output remains inappropriately high and peripheral glucose uptake remains impaired, so the plasma glucose concentration is also increased — her fingerstick values range up to 230 mg/dL. The correct combination is therefore increased glucose, increased insulin, and decreased insulin receptor responsiveness.
- B) Increased | increased | normal — If receptor responsiveness were normal, the elevated insulin concentration would drive glucose into tissues and normalize the plasma glucose. Hyperglycemia despite hyperinsulinemia is the definition of insulin resistance.
- C) Increased | normal | decreased — Insulin resistance normally provokes compensatory hyperinsulinemia. An insulin concentration that is merely normal in the face of sustained hyperglycemia is not the expected pattern in an overweight patient with preserved β-cell output.
- D) Increased | normal | normal — With normal insulin concentrations and normal receptor responsiveness, glucose homeostasis would be intact; this combination cannot explain her hyperglycemia.
- E) Normal | normal | normal — Entirely normal values are incompatible with a documented diagnosis of type 2 diabetes, fingerstick glucose values up to 230 mg/dL, and a hemoglobin A1c of 7%.
Educational objective: Remember the core physiology of type 2 diabetes: decreased target-tissue insulin receptor responsiveness drives compensatory hyperinsulinemia, and hyperglycemia persists because that compensation is incomplete. Increased glucose with increased insulin is the signature of insulin resistance; increased glucose with low insulin indicates β-cell failure, as in type 1 diabetes.
Item 49 — Adverse effect of trimethoprim-sulfamethoxazole [Heme/Onc]
Answer: C — Adverse effect of trimethoprim-sulfamethoxazole
An absolute neutrophil count of 440/mm³ after 6 days of trimethoprim-sulfamethoxazole indicates drug-induced severe neutropenia. ANC = WBC × (segmented neutrophils + bands) = 2200 × 0.20 = 440/mm³. Fever and sore throat are common early manifestations because neutropenia compromises mucosal defense.
The normal hematocrit and platelet count make generalized bone marrow failure less likely. The temporal relationship to a sulfonamide-containing drug, a recognized cause of neutropenia, is the decisive clue. The lymphocyte predominance is relative, reflecting depletion of neutrophils rather than a primary lymphoproliferative process.
- A) Acute mononucleosis usually causes exudative pharyngitis, posterior cervical lymphadenopathy, splenomegaly, and atypical lymphocytosis, typically in a younger patient. It does not explain this marked isolated neutropenia after a new medication.
- B) Acute myelogenous leukemia commonly produces blasts and additional cytopenias from marrow replacement. The preserved hematocrit and platelet count argue against it.
- D) Lisinopril can cause cough or angioedema, but neither produces this isolated severe neutropenia after 2 years of stable use.
- E) Myelofibrosis presents chronically with anemia, splenomegaly, and a leukoerythroblastic blood picture rather than abrupt isolated neutropenia.
- F) Sepsis can cause leukopenia, but this patient is hemodynamically stable without organ dysfunction; the medication exposure and selective neutrophil reduction are more specific.
Educational objective: When fever and sore throat develop soon after starting trimethoprim-sulfamethoxazole, calculate the ANC. Severe isolated neutropenia with preserved hemoglobin and platelets strongly favors a drug adverse effect.
Item 50 — Knee No diagnostic testing indicated, Ankle x-ray [Musculoskeletal]
Answer: C — Knee No diagnostic testing indicated, Ankle x-ray
The knee does not meet Ottawa knee rule criteria, whereas distal fibular tenderness mandates ankle radiographs under the Ottawa ankle rules.
For the knee, he is younger than 55 years, could bear weight after injury, has full flexion, and has neither patellar nor fibular head tenderness. The stable collateral testing, negative Lachman test, and absence of effusion or mechanical symptoms further argue against an acute injury requiring immediate imaging.
For the ankle, pain and swelling are accompanied by bony tenderness over the distal fibula. Tenderness along the distal 6 cm of the posterior fibular margin or at the lateral malleolar tip is an indication for ankle radiographs. Obtain AP, lateral, and mortise views.
- A) Knee radiography is unnecessary because none of the Ottawa knee criteria are present. Ankle radiography is appropriate.
- B) This reverses the correct approach: the reassuring knee examination does not require imaging, but distal fibular tenderness requires an ankle x-ray.
- D) Deferring knee imaging is appropriate, but omitting ankle imaging risks missing a distal fibular or lateral malleolar fracture.
Educational objective: Remember: after acute knee or ankle trauma, apply the Ottawa rules separately to each joint. Weight-bearing ability and full knee flexion can avoid unnecessary knee films, but distal fibular or malleolar bony tenderness warrants ankle radiographs.
Item 51 — X-rays of the left hand and wrist [Endocrine]
Answer: C — X-rays of the left hand and wrist
Short stature with absent breast development at age 13 requires assessment of skeletal maturation; a left hand and wrist radiograph determines bone age. Bone age reflects physiologic maturity and helps distinguish constitutional delay, where it is delayed with preserved growth potential, from familial short stature, where it generally matches chronologic age.
The family history of late puberty supports constitutional delay. Stage 2 pubic hair does not establish central puberty because adrenarche can occur independently of hypothalamic-pituitary-gonadal activation; breast development is the relevant marker in girls. Further laboratory testing, including evaluation for Turner syndrome, chronic disease, thyroid dysfunction, and gonadal failure, should follow based on the growth pattern and bone-age result.
- A) CBC and serum chemistry screen for chronic systemic disease, but they do not assess skeletal maturity or remaining growth potential as directly as bone age.
- B) Urine free cortisol is used when Cushing syndrome is suspected. She lacks obesity, hypertension, or other features of glucocorticoid excess.
- D) Long-bone and spine radiographs are appropriate when disproportionate short stature or skeletal dysplasia is suspected; neither is described.
- E) A skull radiograph is not useful for routine assessment of short stature or delayed puberty. Suspected hypothalamic-pituitary disease is evaluated with targeted hormonal testing and MRI.
Educational objective: When short stature is accompanied by delayed puberty, obtain a left hand and wrist radiograph for bone age. Delayed bone age indicates delayed skeletal maturation and preserved catch-up growth potential.
Item 52 — Corticosteroid injection [Dermatology]
Answer: A — Corticosteroid injection
An enlarging, firm earlobe mass developing after piercing is a keloid, and the appropriate initial treatment is intralesional corticosteroid injection, typically triamcinolone. Keloids represent excessive collagen deposition that extends beyond the original wound and frequently recurs after removal.
Intralesional corticosteroids reduce fibroblast activity and collagen synthesis, gradually flattening and softening the lesion. Injections may need to be repeated at approximately 4-week intervals. Excision is reserved for large, old, or refractory lesions and must be combined with adjuvant measures because surgery alone creates fresh trauma and carries a high recurrence risk.
- B) Cryotherapy can reduce smaller keloids but is generally an alternative or adjunct to intralesional corticosteroids rather than the preferred initial monotherapy.
- C) Laser ablation has variable efficacy and is usually reserved for selected minor or treatment-resistant lesions.
- D) Needle aspiration is appropriate for a fluid-filled lesion such as a cyst or abscess; a keloid is solid fibrous tissue.
- E) Wide excision alone has a high recurrence rate. If excision is required, it should be followed by serial steroid injections, pressure therapy, or another adjuvant modality.
Educational objective: When a firm earlobe mass appears after piercing and grows beyond the injury site, think keloid. Begin with intralesional corticosteroids; avoid excision without adjuvant therapy.
Item 53 — Tube thoracostomy [Respiratory]
Answer: F — Tube thoracostomy
Blunt chest trauma with decreased right-sided breath sounds and near-complete opacification of the right hemithorax indicates a traumatic hemothorax. Her hypoxemia reflects compression of the right lung by pleural blood. The immediate treatment is a large-bore tube thoracostomy, which evacuates the blood, permits lung re-expansion, and quantifies ongoing hemorrhage.
She is tachycardic but normotensive, alert, and ventilating adequately, so intubation is not the next step. Thoracotomy is reserved for major ongoing bleeding, such as an initial chest-tube output exceeding 1500 mL or continued drainage above approximately 200 mL/hour.
- A) Bronchoscopy is used when tracheobronchial injury, airway obstruction, or lobar collapse is suspected. The radiograph shows pleural-space opacification rather than an isolated airway lesion.
- B) Intubation is indicated for respiratory failure or inability to protect the airway. Positive-pressure ventilation does not address the pleural blood and is unnecessary before drainage in this alert, spontaneously ventilating patient.
- C) Thoracic epidural analgesia can improve ventilation in severe rib-fracture pain or flail chest, but it does not evacuate a hemothorax.
- D) Thoracentesis may identify bloody pleural fluid, but traumatic hemothorax requires continuous large-bore drainage rather than one-time needle aspiration.
- E) Thoracotomy is considered only after chest-tube drainage demonstrates massive or persistent hemorrhage, or if the patient becomes hemodynamically unstable.
- G) Observation is inappropriate because this large hemothorax is already causing hypoxemia and significant lung compression.
Educational objective: After blunt trauma, unilateral breath-sound reduction plus hemithoracic opacification indicates hemothorax: treat first with large-bore tube thoracostomy. Use the initial and ongoing chest-tube output to determine whether thoracotomy is required.
Item 54 — Giardia lamblia [Infectious Disease]
Answer: E — Giardia lamblia
Untreated pond water followed by prolonged intermittent, nonbloody diarrhea and weight loss is giardiasis. Giardia cysts survive in freshwater and are acquired by fecal–oral ingestion, particularly during camping. The organism remains in the proximal small intestine, where trophozoite attachment causes microvillous injury and loss of brush-border enzymes, producing malabsorptive diarrhea without tissue invasion.
The stool smear shows the oval Giardia cyst; mature cysts contain four nuclei. Trophozoites, when seen, are pear-shaped, binucleate, and flagellated. The absence of blood, mucus, significant fever, or colitic symptoms separates giardiasis from invasive bacterial diarrhea and amebic dysentery.
- A) Campylobacter jejuni causes acute inflammatory diarrhea, often with fever, severe abdominal pain, fecal leukocytes, and sometimes blood. A 3-month intermittent malabsorptive course after untreated water is not typical.
- B) Clostridioides difficile is associated with antibiotic exposure, hospitalization, or healthcare contact and causes toxin-mediated colitis. None of those risk factors is present.
- C) Entamoeba histolytica invades the colonic mucosa, producing dysentery with blood and mucus; trophozoites may contain ingested erythrocytes. This patient has occult blood–negative stool.
- D) Escherichia coli usually causes an acute diarrheal syndrome linked to contaminated food or travel; invasive or Shiga toxin–producing strains often cause bloody diarrhea.
- F) Salmonella enteritidis causes acute febrile inflammatory gastroenteritis, typically after contaminated poultry or eggs, rather than chronic intermittent malabsorption.
- G) Shigella dysenteriae causes fever, tenesmus, abdominal cramps, and bloody, mucoid diarrhea due to invasive colitis.
Educational objective: When you see camping or untreated freshwater exposure followed by intermittent nonbloody diarrhea, weight loss, and malabsorption, think Giardia lamblia. Remember: Giardia is noninvasive; blood and prominent inflammatory features argue for another pathogen.
Item 55 — 2.6 [Biostatistics & Prevention]
Answer: B — 2.6
Absolute risk reduction is the event rate in the control group minus the event rate in the treated group. The table gives both rates directly: 3.6 invasive breast cancers per 1000 woman-years with placebo and 1.0 per 1000 woman-years with the SERM.
ARR = 3.6 − 1.0 = 2.6 invasive breast cancers prevented per 1000 woman-years.
Because both rates already use the same person-time denominator, the participant counts and total woman-years require no further conversion. This is an absolute difference between two incidence rates, not a ratio.
- A) 0.28 is approximately the ratio of the two rates (1.0 ÷ 3.6). A ratio is a relative measure of effect, not an absolute risk reduction.
- C) 3.6 is the invasive breast cancer rate in the placebo group. It is the starting risk, not the reduction attributable to treatment.
- D) 6 is the difference in the raw number of invasive cancers (13 − 7). Raw counts cannot be subtracted directly here because the two groups contributed very different amounts of follow-up time (7200 versus 3600 woman-years).
- E) 7 is the number of invasive breast cancers in the SERM group, not a rate difference.
Educational objective: Remember: absolute risk reduction equals control event rate minus treatment event rate. When outcomes are reported per person-time, subtract rates expressed with the same person-time denominator.
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Item 56 — Esophagogastroduodenoscopy [Gastrointestinal]
Answer: E — Esophagogastroduodenoscopy
Acute hematemesis localizes the bleeding proximal to the ligament of Treitz, making EGD the next step after initial resuscitation. It directly examines the esophagus, stomach, and duodenum, identifies the bleeding source, permits biopsy of a gastric lesion suggested by early satiety, and allows immediate endoscopic hemostasis.
Her tachycardia indicates clinically significant blood loss; the hematocrit may underestimate an acute hemorrhage because it falls only after plasma-volume equilibration. Normal platelets and INR remove a major procedural barrier. Mesenteric angiography is reserved for ongoing bleeding when endoscopy cannot identify or control the source.
- A) Abdominal CT may evaluate a mass or extraluminal disease but neither localizes mucosal upper GI bleeding reliably nor provides hemostasis.
- B) An octreotide scan detects somatostatin receptor–expressing tumors; it has no role in the initial evaluation of acute hematemesis.
- C) Technetium-99m scintigraphy is used for selected intermittent or obscure bleeding, particularly when endoscopic localization is unsuccessful. It is not first-line for an evident upper GI source.
- D) Colonoscopy evaluates lower GI bleeding. Bright-red hematemesis directly indicates an upper GI source.
- F) Mesenteric angiography can localize and embolize active bleeding, but it follows failed or nondiagnostic endoscopy rather than replacing initial EGD.
Educational objective: When hematemesis persists after initial stabilization, proceed to EGD because it is both diagnostic and therapeutic. Reserve angiography for bleeding that cannot be visualized or controlled endoscopically.
Item 57 — Endoscopic hemostatic therapy [Gastrointestinal]
Answer: D — Endoscopic hemostatic therapy
An ulcerated gastric subepithelial mass with active bleeding requires endoscopic hemostasis now. The early satiety and smooth bulging lesion with ulceration suggest a gastric gastrointestinal stromal tumor (GIST); mucosal ulceration over the tumor explains the hematemesis and anemia.
Management is dictated first by the active hemorrhage, not by tumor characterization. Endoscopic clipping, thermal coagulation, injection combined with a second modality, or hemostatic powder can secure bleeding. Once stable, the lesion can be evaluated with endoscopic ultrasound and targeted tissue sampling, followed by definitive resection when localized and resectable.
- A) Octreotide therapy is used for suspected variceal bleeding and selected recurrent vascular lesions. There is no portal hypertension or variceal source here.
- B) Omeprazole supports clot stability after endoscopic control of high-risk ulcer bleeding but is not a substitute for hemostasis in an actively bleeding lesion.
- C) Tyrosine kinase inhibition with imatinib is used for unresectable, metastatic, or selected high-risk GISTs. It does not provide immediate control of hemorrhage.
- E) Routine mucosal biopsy may be nondiagnostic because GIST arises beneath normal mucosa; more importantly, active bleeding must be controlled before tissue diagnosis.
- F) Endoscopic resection is not the immediate step during active hemorrhage. Definitive resection depends on tumor size, layer of origin, location, and resectability after stabilization and staging.
Educational objective: When endoscopy demonstrates active upper gastrointestinal bleeding, achieve endoscopic hemostasis before biopsy, staging, or definitive tumor treatment. An ulcerated subepithelial gastric mass with bleeding and early satiety should raise concern for GIST.
Item 58 — Biopsy of the vulva [Obstetrics & Gynecology]
Answer: F — Biopsy of the vulva
A new raised, fleshy, bleeding vulvar lesion in a 77-year-old woman requires biopsy because vulvar carcinoma must be excluded histologically. Vulvar squamous cell carcinoma predominantly affects women older than 60; the HPV-independent keratinizing subtype has an average presentation near age 75 and is often unifocal.
The biopsy should be taken from the lesion margin to include abnormal epithelium and adjacent tissue. CT is used after tissue diagnosis when assessing regional nodes or metastatic spread; absent palpable lymphadenopathy does not remove the need for biopsy. Warfarin increases bleeding risk and requires periprocedural planning, but it does not justify delaying diagnosis of a suspicious growth.
- A) Cytologic evaluation can assess associated cervical or vaginal neoplasia but does not establish the diagnosis of a vulvar mass. Tissue architecture and invasion require histology.
- B) CT of the abdomen and pelvis is a staging investigation after malignancy is confirmed, not the initial diagnostic step for an accessible lesion.
- C) Antifungal cream fits candidal vulvovaginitis with pruritus, erythema, and discharge, not a discrete 3-cm fleshy growth.
- D) Corticosteroids are used for inflammatory vulvar dermatoses such as lichen sclerosus, but a raised bleeding lesion must first be biopsied to exclude malignancy.
- E) Colonoscopy evaluates suspected colorectal pathology; the visible vulvar lesion provides a direct and more concerning source of bleeding.
Educational objective: When an older woman has a new raised, ulcerated, or bleeding vulvar lesion, obtain a vulvar biopsy before imaging or empiric topical treatment. Imaging stages confirmed cancer; it does not replace tissue diagnosis.
Item 59 — Spinal stenosis [Musculoskeletal]
Answer: D — Spinal stenosis
Back pain radiating into both legs with paresthesias, provoked by standing or walking and relieved by sitting or lying down, is neurogenic claudication from lumbar spinal stenosis. Lumbar extension narrows the spinal canal and foramina, whereas sitting or forward flexion increases canal dimensions and relieves neural compression. A normal neurologic examination at rest does not exclude the diagnosis.
The closest alternative is vascular claudication, especially given his smoking and cardiovascular risk factors. However, vascular claudication is driven primarily by exertion and improves simply by stopping activity; neurogenic claudication can be triggered by prolonged standing and improves specifically with spinal flexion or sitting. His normal ankle-brachial index further argues against peripheral arterial disease.
- A) Abdominal aortic aneurysm can cause persistent abdominal, flank, or back pain, particularly with expansion or rupture. It does not produce reproducible bilateral leg paresthesias relieved by sitting.
- B) Osteoporosis is generally asymptomatic until a fragility fracture occurs. A vertebral compression fracture causes focal axial pain rather than posture-dependent neurogenic claudication.
- C) Peripheral neuropathy typically causes persistent distal, symmetric sensory symptoms in a stocking distribution. Symptoms are not characteristically induced by standing and rapidly relieved by sitting.
- E) Vascular claudication causes exertional muscle pain from arterial insufficiency and is supported by diminished pulses or a reduced ankle-brachial index. Standing alone provoking symptoms and an ankle-brachial index of 1.0 favor a neurogenic cause.
Educational objective: When standing or walking causes back and bilateral leg symptoms that improve with sitting or lumbar flexion, think lumbar spinal stenosis. Preserved pulses and a normal ankle-brachial index help separate neurogenic from vascular claudication.
Item 60 — Measurement of urine and plasma osmolarity [Renal]
Answer: D — Measurement of urine and plasma osmolarity
Severe euvolemic hyponatremia in a patient taking an SSRI and antipsychotic raises SIAD, but psychogenic polydipsia remains an important alternative in chronic schizophrenia. Plasma and urine osmolality separate these mechanisms.
Plasma osmolality first confirms true hypotonic hyponatremia and excludes pseudohyponatremia; the normal glucose already argues against hypertonic, glucose-mediated hyponatremia. Urine osmolality then assesses whether AVP is appropriately suppressed: urine osmolality <100 mOsm/kg favors primary polydipsia, whereas urine that remains concentrated despite hypo-osmolality indicates persistent AVP activity, as in SIAD. Subsequent urine sodium and endocrine testing can refine the diagnosis.
- A) CT scan of the chest may be appropriate later because his smoking history raises concern for small-cell lung carcinoma. Biochemical confirmation of an SIAD pattern should come first.
- B) Cortisol and TSH help exclude adrenal insufficiency and hypothyroidism before diagnosing SIAD, but they do not replace the initial confirmation and classification of hypotonic hyponatremia.
- C) Low serum uric acid supports SIAD, whereas hyperuricemia favors volume depletion. It is an adjunct, not the primary test distinguishing SIAD from polydipsia.
- E) Brain MRI is reserved for clinical suspicion of a CNS cause; there are no focal neurologic findings to prioritize neuroimaging.
Educational objective: When euvolemic hyponatremia occurs in a patient at risk for both SIAD and primary polydipsia, measure plasma and urine osmolality first. Dilute urine suggests polydipsia; inappropriately concentrated urine indicates persistent AVP activity.
Item 61 — Provide palliative therapy only [Ethics]
Answer: D — Provide palliative therapy only
The patient’s previously expressed refusal of mechanical ventilation should be honored, even without a written advance directive. He now lacks decision-making capacity due to severe hypoxemia and altered mentation, so his wife should use substituted judgment—choosing what he would have chosen, not what another family member prefers.
Emergency treatment is presumed only when the patient’s wishes are unknown. Here, his recent, specific statement against ventilation provides convincing evidence of his preference. The daughter cannot override that refusal. Care should therefore shift to comfort, with aggressive relief of dyspnea, anxiety, and other distressing symptoms.
- A) Intubation would be appropriate if his preferences were unknown. Here it directly violates his expressed refusal of mechanical ventilation.
- B) Ethics consultation can help when preferences are uncertain or conflict cannot be resolved, but intubating first would disregard a known treatment refusal.
- C) Endotracheal intubation without ventilation neither addresses his respiratory failure nor respects his goals of care.
- E) Courts are generally unnecessary when an authorized surrogate can communicate the wishes of a patient who lacks capacity. His wife’s substituted judgment should guide treatment.
Educational objective: When an incapacitated, terminally ill patient has previously expressed a specific treatment preference, the surrogate should honor that preference through substituted judgment—even without formal paperwork. Emergency treatment is not presumed when prior wishes are known.
Item 62 — Penicillin prophylaxis [Heme/Onc]
Answer: E — Penicillin prophylaxis
An FS newborn-screening pattern means fetal hemoglobin and sickle hemoglobin are present without detectable HbA, supporting sickle cell disease—usually HbSS or HbSβ0-thalassemia. Begin penicillin prophylaxis while arranging repeat hemoglobin analysis to confirm the phenotype.
Infants with sickle cell disease develop progressive splenic dysfunction and are highly vulnerable to invasive infection from encapsulated bacteria, particularly Streptococcus pneumoniae. Penicillin should therefore begin early, before functional asplenia becomes clinically apparent; a normal examination at 5 days does not alter preventive management.
- A) Deferoxamine treats transfusional iron overload. This infant has neither chronic transfusion exposure nor evidence of iron excess.
- B) Hydroxyurea is disease-modifying therapy that increases HbF, but it is not the immediate preventive intervention following an FS newborn screen.
- C) Iron should be given only for documented iron deficiency; sickle hemoglobin on screening is not an indication.
- D) Chronic transfusions are reserved for specific complications or high-risk settings, not an asymptomatic newborn with screen-detected disease.
- F) Vitamin B12 treats or prevents deficiency-related megaloblastic anemia. It does not prevent the infectious complications of sickle cell disease.
Educational objective: When newborn screening shows FS with no HbA, think sickle cell disease and start penicillin prophylaxis early while confirming the hemoglobin phenotype. Clinical symptoms are delayed by high neonatal HbF, but preventive care should not be delayed.
Item 63 — Levothyroxine therapy [Endocrine]
Answer: B — Levothyroxine therapy
Elevated TSH with a low free T4 confirms primary congenital hypothyroidism and requires immediate levothyroxine therapy. The infant’s normal examination does not change management; most affected newborns are clinically asymptomatic because maternal thyroid hormone provides partial support before birth.
Treatment must begin promptly because thyroid hormone is critical for early brain development, and delayed correction can cause irreversible neurodevelopmental impairment. Oral levothyroxine is started at 10–15 μg/kg/day, with subsequent dose adjustment using age-specific TSH and free T4 targets. Etiologic imaging may be performed later, but it must never delay treatment.
- A) Hydrocortisone is indicated when adrenal insufficiency is suspected, particularly before thyroid replacement in central hypothyroidism. This infant has primary hypothyroidism, demonstrated by elevated TSH with low free T4.
- C) Thyroglobulin may help characterize the etiology but has substantial overlap among congenital thyroid disorders. Serial measurements neither replace thyroid hormone nor guide initial management.
- D) Observation is inappropriate because free T4 is already low. Serial testing without treatment risks preventable neurologic injury.
- E) Thyroid scintigraphy can identify ectopia, agenesis, or dyshormonogenesis, but establishing the cause is secondary to immediate hormone replacement.
- F) Ultrasonography can assess whether a normally positioned thyroid is present, but it may miss ectopic tissue and must not postpone therapy.
Educational objective: When a newborn has elevated TSH plus low free T4, diagnose primary congenital hypothyroidism and start levothyroxine immediately—even if the infant appears healthy. Imaging determines etiology; it does not precede treatment.
Item 64 — CT scan of the abdomen [Gastrointestinal]
Answer: C — CT scan of the abdomen
Migratory periumbilical-to-right-lower-quadrant pain suggests acute appendicitis, but the palpable fullness and 2 months of intermittent diarrhea broaden the differential to an appendiceal phlegmon or abscess and terminal ileal Crohn disease. CT of the abdomen is the best next study because it can confirm appendiceal inflammation, define complications, and identify an alternative intra-abdominal process.
CT findings supporting appendicitis include an enlarged appendix with wall thickening or enhancement and periappendiceal fat stranding, fluid, phlegmon, or abscess. The recent upper respiratory infection is not sufficient to favor mesenteric adenitis over these stronger abdominal findings.
- A) Abdominal ultrasonography is useful as an initial radiation-sparing study, particularly in children and pregnancy, but it is operator-dependent and may not visualize the appendix. CT better evaluates the RLQ fullness and competing diagnosis of ileocecal inflammation.
- B) Air-contrast barium enema is not used to evaluate acute RLQ pain and should be avoided when active inflammation or perforation is possible.
- D) A technetium-99m pertechnetate scan detects ectopic gastric mucosa in Meckel diverticulum, typically investigated with unexplained lower gastrointestinal bleeding rather than migratory RLQ pain and tenderness.
- E) Small bowel follow-through can evaluate chronic small-bowel disease but is not appropriate during an acute surgical abdomen; it cannot assess periappendiceal inflammation and abscess as effectively as CT.
Educational objective: When migratory RLQ pain suggests appendicitis but chronic bowel symptoms or an abdominal mass raise concern for ileocecal disease or a complication, obtain abdominal CT to define the diagnosis and its extent.
Item 65 — Transabdominal ultrasonography [Obstetrics & Gynecology]
Answer: E — Transabdominal ultrasonography
Painless third-trimester bleeding after intercourse should be treated as placenta previa until placental location is established. Transabdominal ultrasonography is the appropriate next step because it identifies whether the placenta overlies or approaches the internal cervical os without manipulating the cervix.
She is hemodynamically stable, and the fetal tracing has no decelerations, so immediate delivery is not yet required. A digital cervical examination must be withheld until previa is excluded, as disruption of placental tissue over the os can precipitate catastrophic hemorrhage.
- A) Cesarean delivery now is indicated for uncontrolled hemorrhage, maternal instability, fetal compromise, or confirmed placenta previa requiring delivery. None has yet been established.
- B) Digital examination of the cervix can provoke severe bleeding when placenta previa is present. Placental location must be determined first.
- C) Magnesium sulfate is used for seizure prophylaxis in severe preeclampsia/eclampsia or for fetal neuroprotection at earlier gestational ages; neither indication is present.
- D) Oxytocin would augment labor and may worsen bleeding before the cause of antepartum hemorrhage and placental location are known.
Educational objective: When painless third-trimester bleeding occurs, especially after intercourse, think placenta previa. Perform ultrasonography before any digital cervical examination.
Item 66 — tell the son the decision belongs to the patient [Ethics]
Answer: A — tell the son the decision belongs to the patient
The patient has decision-making capacity: he is alert, understands that a nursing facility offers better care, and can express a consistent preference for home care with visiting nursing support. A capable adult retains the right to choose among available discharge plans, even when clinicians or family members consider another option safer.
Power of attorney does not displace the decisions of a patient who currently has capacity. A health care proxy acts only when the patient cannot make the relevant decision or voluntarily delegates it. Disagreement with medical advice is not evidence of incapacity.
- B) The physical therapist may recommend institutional care but cannot override an informed decision by a capable patient.
- C) A family meeting may help coordinate home support, but the children do not collectively acquire authority over a capable parent. Discharge planning need not be suspended pending family consensus.
- D) Psychiatric consultation is unnecessary. Capacity is decision-specific and can ordinarily be assessed clinically; this patient demonstrates understanding, appreciation, and communication of a choice.
- E) Reviewing the document would matter if the patient lacked capacity or had delegated decision-making. The son’s power of attorney is not activated merely because he disagrees with his father.
Educational objective: Remember: a capable adult’s informed choice prevails over recommendations from clinicians, therapists, and family. A health care proxy exercises authority only when the patient lacks decision-making capacity or has voluntarily delegated the decision.
Item 67 — Small vessel disease [Neurology]
Answer: C — Small vessel disease
Acute contralateral hemiplegia plus a hyperattenuating putaminal lesion is hypertensive intracerebral hemorrhage from rupture of a small penetrating artery. The putamen is the commonest site of hypertensive hemorrhage; extension toward the adjacent internal capsule produces dense weakness of the opposite face, arm, and leg. His severe hypertension provides the underlying small-vessel injury.
Hyperattenuation on noncontrast CT represents acute blood, not an uncomplicated lacunar infarct. The absent reflexes do not exclude a central lesion: severe acute corticospinal injury can initially cause flaccidity and hyporeflexia before spasticity and hyperreflexia emerge.
- A) Amyloid angiopathy causes recurrent lobar hemorrhages, typically at the cortical-subcortical junction in older adults, rather than a deep putaminal bleed.
- B) Embolism usually produces an ischemic arterial-territory stroke, often with cortical findings such as aphasia, neglect, or visual field loss. It does not account for the characteristic hypertensive deep hemorrhage.
- D) Cerebral vasculitis more often causes multifocal ischemic lesions with headache, encephalopathy, or systemic inflammatory features. A resolved upper respiratory illness does not outweigh the deep hemorrhage pattern.
- E) Cerebral venous thrombosis commonly presents with progressive headache, seizures, papilledema, or hemorrhagic venous infarction crossing arterial boundaries—not an isolated putaminal hematoma.
Educational objective: When noncontrast CT shows acute blood in the putamen, thalamus, pons, or cerebellum in a hypertensive patient, think rupture of a small penetrating artery. Deep hemorrhage favors hypertensive small-vessel disease; lobar hemorrhage favors cerebral amyloid angiopathy.
Item 68 — Type of vaginal discharge [Obstetrics & Gynecology]
Answer: D — Type of vaginal discharge
Homogeneous white-gray discharge with vaginal pH 5.5 indicates bacterial vaginosis, the strongest infection risk before uterine instrumentation. Normal vaginal pH is acidic; a pH above 4.5 with characteristic discharge reflects loss of lactobacilli and overgrowth of mixed anaerobic flora.
During suction curettage, cervical dilation and transcervical instrumentation can carry this endogenous vaginal flora into the uterine cavity, producing postabortal endometritis or pelvic infection. Sterile instruments and povidone-iodine reduce exogenous contamination but do not eliminate infection arising from abnormal vaginal flora.
- A) A resolved upper respiratory infection two weeks earlier does not predispose to postoperative pelvic infection.
- B) Remote HSV-2 with no active genital lesions is not the relevant source of ascending polymicrobial infection.
- C) Obesity is a general risk factor for surgical-site infection, particularly with abdominal incisions, but bacterial vaginosis is the more direct risk in a transcervical procedure.
- E) Vulvar shaving may cause microabrasions and increase incisional skin infection risk, but suction curettage creates no vulvar incision.
Educational objective: When homogeneous gray-white discharge accompanies vaginal pH >4.5, think bacterial vaginosis. Before transcervical uterine procedures, abnormal vaginal flora is a major risk for ascending postprocedural endometritis.
Item 69 — Gout [Musculoskeletal]
Answer: B — Gout
Sudden excruciating pain, erythema, and swelling of the first metatarsophalangeal joint is podagra—the characteristic presentation of acute gout. Her inability to tolerate compression stockings or walk reflects the intense inflammatory pain typical of a gout flare.
Several factors reinforce the diagnosis: she is postmenopausal, has diabetes and mild renal impairment, and takes hydrochlorothiazide, which promotes hyperuricemia. A serum uric acid of 7.8 mg/dL is supportive but not diagnostic; urate levels may even be normal during an acute attack. If confirmation is required, joint aspiration shows needle-shaped, strongly negatively birefringent monosodium urate crystals.
- A) Cellulitis causes diffuse skin and subcutaneous inflammation rather than inflammation centered on the first MTP joint. Gout can closely mimic cellulitis because of marked periarticular erythema.
- C) An infected mucoid cyst typically occurs near the dorsal distal interphalangeal joint and nail fold, not at the first MTP joint.
- D) Osteoarthritis causes chronic activity-related pain, stiffness, and restricted movement; it does not usually produce abrupt, intensely painful podagra.
- E) Pseudogout commonly affects the knee or wrist in older adults; first-MTP involvement is rare. Aspiration would show rhomboid-shaped, weakly positively birefringent calcium pyrophosphate crystals.
- F) Rheumatoid arthritis produces a chronic, symmetric inflammatory polyarthritis, typically involving the MCP and PIP joints rather than an isolated acutely inflamed great toe.
Educational objective: When sudden severe monoarthritis involves the first MTP joint, think acute gout. Remember that serum urate alone neither confirms nor excludes an acute flare; definitive diagnosis is crystal identification in synovial fluid.
Item 70 — Coronary artery disease [Cardiovascular]
Answer: C — Coronary artery disease
Long-standing type 1 diabetes plus 3-mm ST-segment depression early during exercise indicates coronary artery disease with silent myocardial ischemia. Horizontal or downsloping exercise-induced ST depression >1 mm is a positive ischemic response; depression >2 mm at a low workload suggests more severe ischemic disease and carries adverse prognostic significance.
The absence of chest pain does not make the test benign. Diabetic autonomic neuropathy—supported here by distal sensory neuropathy—can blunt ischemic pain, allowing significant CAD to present silently. Diabetes also accelerates atherosclerosis in large and medium-sized arteries, including the coronaries. The soft, early-peaking grade 1/6 ejection murmur is an incidental flow murmur rather than the cause of the abnormal stress test.
- A) Cardiomyopathy may produce heart failure findings, arrhythmias, or characteristic dynamic murmurs, none of which are present. Exercise-induced ST depression in this clinical context indicates ischemia rather than primary myocardial disease.
- B) Congenital heart disease would require a compatible structural murmur, fixed split S2, cyanosis, or another congenital finding. A soft early-peaking murmur alone is insufficient.
- D) Significant valvular disease generally produces a louder, anatomically characteristic murmur with radiation or associated examination findings. It does not explain silent ischemic ST depression at low workload.
- E) A 3-mm ST-segment depression early during exercise is markedly abnormal, even without angina.
Educational objective: When a patient with long-standing diabetes develops exercise-induced ST depression without chest pain, think silent myocardial ischemia from coronary artery disease. Diabetic neuropathy can remove the warning symptom, not the ischemia.
Item 71 — Excessive alcohol use [Cardiovascular]
Answer: C — Excessive alcohol use
Six beers daily followed by new-onset hypertension = an alcohol-induced pressor effect. Consumption of three or more drinks per day produces a dose-dependent rise in blood pressure, which can return toward baseline within weeks of abstinence. The temporal link is strong: his blood pressure was previously normal, and the elevation appeared after two months of sustained heavy drinking.
Although acute ethanol exposure can cause peripheral vasodilation, regular heavy intake raises blood pressure. His young age, normal BMI, and lack of symptoms or examination findings further favor this newly acquired lifestyle exposure over primary or structural causes.
- A) Cigarette smoking causes transient sympathetic activation and substantially increases cardiovascular risk, but it is less likely than six daily beers to explain sustained resting hypertension in this presentation.
- B) Essential hypertension is common and may occur in young adults, but the abrupt elevation after a major increase in alcohol intake provides a direct reversible cause.
- D) Pheochromocytoma typically produces episodic or sustained hypertension with catecholamine-related features such as headache, palpitations, diaphoresis, and tremor, none of which are present.
- E) Renal artery stenosis is considered with abrupt or resistant hypertension, renal dysfunction, an abdominal bruit, or characteristic demographic clues. This patient has none of these supporting findings.
Educational objective: When new hypertension follows sustained intake of three or more alcoholic drinks daily, think alcohol-induced hypertension. Heavy alcohol consumption raises blood pressure in a dose-dependent manner, and abstinence can normalize it within weeks.
Item 72 — Kaposi sarcoma [Dermatology]
Answer: C — Kaposi sarcoma
Painless violaceous plaques in a young man with unexplained weight loss are Kaposi sarcoma. These vascular lesions may appear as brown, red-purple, or violaceous macules, plaques, and nodules, including on the upper extremities.
In this context, Kaposi sarcoma should prompt evaluation for underlying HIV infection and cellular immunodeficiency. It is an AIDS-defining malignancy driven by human herpesvirus 8; impaired immune surveillance permits viral reactivation and vascular tumor development.
- A) Actinic keratosis produces rough, scaly premalignant lesions on chronically sun-exposed skin, typically in older fair-skinned patients—not smooth violaceous plaques.
- B) Dermatitis herpetiformis causes intensely pruritic, grouped vesicles and papules on extensor surfaces and is associated with gluten sensitivity.
- D) Lichen planus presents with pruritic, purple, polygonal, flat-topped papules, often with Wickham striae; the painless plaque-like lesions with constitutional weight loss favor Kaposi sarcoma.
- E) Seborrheic dermatitis causes greasy scales over erythematous patches, predominantly on the scalp, eyebrows, nasolabial folds, ears, and central chest.
Educational objective: When you see painless violaceous macules, plaques, or nodules in a young patient with constitutional symptoms, think Kaposi sarcoma and evaluate for HIV. Remember the association: Kaposi sarcoma = HHV-8 plus impaired cellular immunity.
Repeating themes across blocks? The topics that recur exam after exam are collected in Step 2 CK chronic repeats.
Item 73 — Measurement of serum follicle-stimulating hormone concentration [Obstetrics & Gynecology]
Answer: A — Measurement of serum follicle-stimulating hormone concentration
Progressive cycle lengthening followed by 6 months of amenorrhea and hot flashes indicates the menopausal transition; serum FSH is the appropriate test to document declining ovarian function at this relatively young age.
Follicular depletion reduces ovarian inhibin and estradiol feedback, causing FSH to rise earlier and more prominently than LH. FSH is also less variable than LH and better distinguishes ovarian insufficiency from a central hypothalamic-pituitary cause of amenorrhea. Her long smoking history supports an earlier menopausal transition. She cannot yet be diagnosed clinically with menopause, which requires 12 consecutive months of amenorrhea and is therefore retrospective.
- B) LH also rises as ovarian feedback declines, but later and less consistently than FSH; it is not the preferred marker of ovarian failure.
- C) Testosterone measurement is appropriate when amenorrhea is accompanied by hirsutism, virilization, or other evidence of androgen excess, none of which is present.
- D) ECG may evaluate persistent or concerning palpitations, but her normal pulse and vasomotor symptoms make ovarian endocrine evaluation the diagnostic priority.
- E) Pelvic ultrasonography is useful for suspected uterine or adnexal pathology. Her gradual menstrual transition, normal pelvic examination, and vasomotor symptoms indicate an endocrine rather than structural process.
Educational objective: When progressive menstrual irregularity and hot flashes occur at an unexpectedly young age, measure serum FSH to assess ovarian insufficiency. Remember: loss of inhibin and estradiol feedback raises FSH more prominently than LH.
Item 74 — report to the clinic administrator and cover the rest of the clinic without him [Ethics]
Answer: E — report to the clinic administrator and cover the rest of the clinic without him
Grogginess, slurred speech, and alcohol odor indicate an impaired physician who must be removed from patient care immediately. The colleague’s first obligations are to protect patients and report the concern through the appropriate institutional chain of command—here, the clinic administrator. Continuing the clinic without the impaired physician preserves patient care while allowing the institution to initiate formal assessment and intervention.
A single observed episode does not establish alcohol use disorder, but that distinction does not affect today’s decision: observable impairment is sufficient to prohibit clinical duties. Reporting directly to the state medical board is not the initial step when an institutional supervisor is available; external reporting depends on applicable laws and institutional procedures.
- A) Allowing an impaired physician to continue evaluating patients exposes them to preventable harm; retrospective discussion is inadequate.
- B) Canceling the clinic protects patients but unnecessarily disrupts care when another physician can conduct the remaining sessions. It also fails to initiate formal reporting.
- C) A physician assistant should not independently evaluate and discharge all patients merely to conceal or bypass the physician’s impairment.
- D) Direct confrontation alone does not ensure institutional documentation, assessment, or appropriate follow-up. The clinical supervisor must be notified.
- F) State medical board reporting may become necessary under state law or institutional policy, but the immediate first report should be to the clinic administrator or clinical director.
Educational objective: When a physician shows observable impairment while providing care, immediately remove them from clinical duties, ensure continuity of patient care, and report the concern to the appropriate clinical supervisor. Patient safety takes priority over collegial loyalty.
Item 75 — No additional testing is indicated [Renal]
Answer: E — No additional testing is indicated
Transient proteinuria during an acute urinary illness followed by a normal repeat urinalysis requires no further evaluation. Her dysuria and frequency have resolved, and the current urine is negative for protein, blood, leukocyte esterase, and nitrite, with no significant pyuria or hematuria.
Protein quantification is appropriate when proteinuria persists on repeat testing or when renal disease is otherwise suspected. Here, the normal specific gravity also makes a false-negative dipstick from markedly dilute urine unlikely. There are no clinical or urinary findings suggesting ongoing infection, glomerular disease, obstruction, or malignancy.
- A) A spot urine albumin-to-creatinine ratio quantifies persistent albuminuria and is useful when renal disease is suspected. A single transient positive dipstick followed by a normal urinalysis does not warrant it.
- B) A 24-hour urine collection measures protein excretion but is unnecessary without persistent proteinuria; spot ratios are generally less cumbersome when quantification is needed.
- C) Renal ultrasonography is used for suspected obstruction, stones, masses, or structural renal disease. None is suggested by this asymptomatic patient’s normal examination and urinalysis.
- D) Sulfosalicylic acid detects total urinary protein, including nonalbumin proteins missed by dipstick. It is reserved for suspected overflow proteinuria, such as light chains, which this presentation does not support.
Educational objective: When proteinuria detected during an acute illness disappears on repeat urinalysis, think transient proteinuria and stop the work-up. Quantify protein only when it persists or there is independent evidence of renal disease.
Item 76 — Surgical debridement [Dermatology]
Answer: D — Surgical debridement
Severe progressive pain after minor trauma, rapidly spreading edema and cellulitis, hemorrhagic bullae, tachycardia, and borderline hypotension indicate necrotizing fasciitis. Hemorrhagic bullae reflect vascular thrombosis and deep tissue destruction—not uncomplicated cellulitis.
After immediate resuscitation and broad-spectrum IV antibiotics, urgent surgical exploration and radical debridement are the next steps. Exploration confirms the diagnosis, defines fascial involvement, provides deep tissue for culture, relieves compartment pressure, and removes necrotic tissue. Antibiotics penetrate devitalized tissue poorly, so medical therapy alone is inadequate. Imaging or bedside sampling must not delay source control.
- A) Fine-needle aspiration may provide fluid for culture but cannot assess fascial viability or control a rapidly advancing deep infection.
- B) Hyperbaric oxygen is an adjunct in selected cases, particularly clostridial myonecrosis. It never precedes or delays surgery and antibiotics.
- C) MRI can delineate fascial involvement when the diagnosis is uncertain in a stable patient. This presentation already mandates exploration, and imaging would waste critical time.
- E) Observation is unsafe because necrotizing soft-tissue infection can rapidly progress to shock, multiorgan failure, and death despite initially limited trauma.
Educational objective: When severe pain after minor trauma progresses to edema, toxicity, and hemorrhagic or violaceous bullae, think necrotizing fasciitis. Begin resuscitation and broad-spectrum antibiotics, but obtain immediate surgical exploration and debridement without waiting for imaging.
Item 77 — Fasting glucose tolerance test [Obstetrics & Gynecology]
Answer: C — Fasting glucose tolerance test
Two previous macrosomic infants, class II obesity, and diabetes in both parents demand early glucose testing at the first prenatal visit. These are strong risk factors for undiagnosed overt diabetes or early gestational diabetes; waiting for routine screening at 24–28 weeks would delay diagnosis.
Maternal hyperglycemia drives fetal hyperglycemia and compensatory fetal hyperinsulinemia, producing excessive fetal growth. Her prior infants weighed more than 4 kg—including one delivered at only 37 weeks—which is the decisive obstetric clue. Early testing assesses current glycemic status; women without early diabetes still undergo routine gestational diabetes screening at 24–28 weeks.
- A) Antiphospholipid antibody testing is appropriate after maternal recurrent pregnancy loss, fetal death, thrombosis, or other qualifying pregnancy morbidity. A sister’s stillbirth does not establish an indication.
- B) Chest radiography is not routine solely because she immigrated from Mexico. Tuberculosis evaluation begins with risk assessment and screening testing, with chest imaging used when infection or active disease is suspected.
- D) Maternal serum α-fetoprotein is a second-trimester screen, generally obtained at 16–20 weeks, primarily for open neural tube defects.
- E) Free thyroxine is measured when thyroid disease is suspected or thyroid-stimulating hormone is abnormal; this patient has no thyroid-related findings.
Educational objective: When early pregnancy is accompanied by obesity, a strong family history of diabetes, and prior infants weighing more than 4 kg, screen for diabetes immediately rather than waiting until 24–28 weeks.
Item 78 — Elder neglect [Geriatrics]
Answer: B — Elder neglect
Abrupt loss of diabetes control plus missed appointments, poor hygiene, and dehydration in a cognitively intact older adult living with a dependent family member indicates elder neglect. Neglect is failure to provide essential care, including medications, nutrition, hydration, hygiene, and access to medical follow-up; it may be intentional or unintentional.
Her HbA1c was previously well controlled, making a sudden fasting glucose of 380 mg/dL concerning for disrupted medication administration or caregiving rather than progression of diabetes alone. Normal orientation, intact memory, and absence of a depressive syndrome argue against impaired self-care from dementia or major depression. The social change—her unemployed son moving into the home—adds a significant safeguarding concern.
- A) Dietary indiscretion can worsen glycemia but does not account for missed appointments, an unkempt appearance, and evidence of inadequate hydration and care.
- C) Major depressive disorder requires depressed mood or anhedonia with additional symptoms causing functional impairment. Flat affect alone, with normal mood and no reported neurovegetative symptoms, is insufficient.
- D) Pancreatic malignancy may cause new-onset or worsening diabetes, typically with concerning features such as weight loss, abdominal or back pain, or jaundice; these are absent.
- E) Urinary tract infection can precipitate hyperglycemia, but she has no urinary symptoms, nitrites, or leukocyte esterase.
Educational objective: When previously stable chronic disease abruptly deteriorates in a cognitively intact older adult who is unkempt, dehydrated, and missing medical care, think elder neglect and assess immediate safety and caregiving conditions.
Item 79 — serum Borrelia burgdorferi antibody testing [Infectious Disease]
Answer: B — serum Borrelia burgdorferi antibody testing
Peripheral CN VII palsy plus lymphocytic meningitis in a child from New Jersey is early disseminated Lyme neuroborreliosis. Involvement of both the forehead and lower face localizes the weakness to the facial nerve rather than a supranuclear lesion. The preceding headache, photophobia, neck stiffness, and CSF lymphocytic pleocytosis with mildly elevated protein make idiopathic Bell palsy insufficient to explain the presentation.
Serum Lyme serology is the appropriate next diagnostic step, typically using a two-tier antibody-testing strategy. Facial palsy may be the first or only recognizable manifestation of Lyme disease; absence of erythema migrans or a recalled tick bite does not exclude it.
- A) Serum angiotensin-converting enzyme activity may support sarcoidosis when facial neuropathy accompanies pulmonary, ocular, or other systemic findings. Nothing here favors neurosarcoidosis over infection acquired in an endemic area.
- C) CMV testing is more relevant in immunocompromised patients or congenital infection. It does not fit this immunocompetent adolescent with an endemic exposure pattern.
- D) Antinuclear antibody testing is used when systemic autoimmune disease is suspected. There are no rheumatologic, renal, hematologic, or cutaneous features suggesting such a disorder.
- E) Serum protein electrophoresis evaluates monoclonal gammopathies and selected inflammatory states. It has no diagnostic role in this acute facial neuropathy with aseptic meningitis.
Educational objective: When peripheral facial palsy is accompanied by headache, neck stiffness, or lymphocytic CSF—especially in a Lyme-endemic region—think Lyme neuroborreliosis and obtain serum Borrelia antibody testing.
Item 80 — Nebulized epinephrine [Respiratory]
Answer: D — Nebulized epinephrine
A barking cough, hoarse cry, and inspiratory stridor after a viral prodrome identify croup. Stridor at rest with moderate suprasternal and subcostal retractions indicates moderate upper-airway obstruction, requiring nebulized epinephrine for rapid mucosal vasoconstriction and reduction of subglottic edema.
A corticosteroid should also be administered because it provides sustained improvement, but its onset is slower. Among the choices, nebulized epinephrine is the appropriate initial pharmacotherapy for immediate relief. The child must be observed afterward because its effect is transient and symptoms may recur.
- A) Intravenous dexamethasone is effective in croup, but nebulized epinephrine provides faster relief when stridor is present at rest. Dexamethasone can usually be given orally unless oral administration is not feasible.
- B) Nebulized albuterol treats lower-airway bronchospasm and wheezing; croup is subglottic upper-airway edema producing stridor.
- C) Nebulized budesonide can reduce croup symptoms, but it does not replace epinephrine for rapid treatment of moderate obstruction.
- E) Oral albuterol is ineffective for subglottic edema and has no role in acute croup.
- F) Oral prednisone has a slower onset and is less preferred than dexamethasone for croup; it will not provide the immediate airway improvement needed here.
- G) Subcutaneous epinephrine is not the preferred route for croup. Nebulization delivers the drug directly to the edematous upper airway.
Educational objective: When a child with a barking cough has stridor at rest and retractions, think moderate-to-severe croup: give nebulized epinephrine for rapid relief and a corticosteroid for sustained benefit.
Continue with the rest of the Free 120
- Block 1 (items 1–40)
- Block 2 (items 41–80)
- Block 3 (items 81–120)
- What does my Free 120 score mean? Score-to-readiness guide
- Free 120 hub: format, timing and how to take it
Last reviewed for the 2026 exam window. Spotted an error? Tell us and we will correct it — accuracy matters more to us than being first.