Free 120 Step 2 CK Block 3 covers items 81–120 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 3 actually tests
Block 3 of the Free 120 covers items 81–120. 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 |
|---|---|
| Psychiatry | 6 |
| Obstetrics & Gynecology | 4 |
| Endocrine | 4 |
| Respiratory | 4 |
| Renal | 3 |
| Quality & Safety | 3 |
| Gastrointestinal | 3 |
| Heme/Onc | 2 |
| Dermatology | 2 |
| Neurology | 2 |
| Infectious Disease | 1 |
| Musculoskeletal | 1 |
| Immunology | 1 |
| Geriatrics | 1 |
| ENT & Ophthalmology | 1 |
| Cardiovascular | 1 |
| Biostatistics & Prevention | 1 |
Answer key — Free 120 Step 2 CK Block 3 (items 81–120)
Score yourself first, then read the explanation for anything you missed or guessed.
| Item | Answer | System |
|---|---|---|
| Item 81 | D — Ultrasonography of the bladder | Renal |
| Item 82 | D — Premature closure | Quality & Safety |
| Item 83 | E — Mirtazapine | Psychiatry |
| Item 84 | A — Female factor infertility | Obstetrics & Gynecology |
| Item 85 | A — Ductal carcinoma in situ | Heme/Onc |
| Item 86 | B — Diagnosis-driven reminders in patient charts | Quality & Safety |
| Item 87 | B — Dicloxacillin therapy | Obstetrics & Gynecology |
| Item 88 | E — No additional diagnostic steps are indicated | Endocrine |
| Item 89 | E — No abnormalities | Endocrine |
| Item 90 | A — weekly structured briefings plus daily huddles | Quality & Safety |
| Item 91 | D — Ultrasonography of the kidneys and bladder | Renal |
| Item 92 | B — Azithromycin | Infectious Disease |
| Item 93 | D — Sputum culture | Respiratory |
| Item 94 | E — weight bearing as tolerated, with no further workup | Musculoskeletal |
| Item 95 | C — Diverticulosis | Gastrointestinal |
| Item 96 | E — Normal development | Psychiatry |
| Item 97 | B — CT scan of the abdomen and pelvis | Renal |
| Item 98 | C — Hypersensitivity pneumonitis | Respiratory |
| Item 99 | A — Cognitive behavioral therapy | Psychiatry |
| Item 100 | C — Lymphopenia | Immunology |
| Item 101 | C — Administration of Rho(D) immune globulin | Obstetrics & Gynecology |
| Item 102 | B — Flora | Dermatology |
| Item 103 | D — Chronic myeloid leukemia | Heme/Onc |
| Item 104 | E — Pulmonary function testing | Respiratory |
| Item 105 | A — Buspirone | Psychiatry |
| Item 106 | E — Parkinson disease | Neurology |
| Item 107 | C — Contact adult protective services | Geriatrics |
| Item 108 | D — Methamphetamine | Psychiatry |
| Item 109 | D — plasma and urinary catecholamines and metanephrines | Endocrine |
| Item 110 | A — Abstinence from alcoholic beverages | Gastrointestinal |
| Item 111 | B — Heat avoidance | Dermatology |
| Item 112 | B — it roughly doubles her risk of death over 3 months | Psychiatry |
| Item 113 | D — Zenker diverticulum | Gastrointestinal |
| Item 114 | E — Observation only | Obstetrics & Gynecology |
| Item 115 | E — nothing further is needed at this time | ENT & Ophthalmology |
| Item 116 | H — Pulmonary infarction | Respiratory |
| Item 117 | D — Ruptured abdominal aortic aneurysm | Cardiovascular |
| Item 118 | D — Neurogenic bladder | Neurology |
| Item 119 | A — Extrapolation of findings beyond data | Biostatistics & Prevention |
| Item 120 | D — Subacute thyroiditis | Endocrine |
Free 120 Step 2 CK Block 3 explanations: items 81–120
Item 81 — Ultrasonography of the bladder [Renal]
Answer: D — Ultrasonography of the bladder
Abrupt oliguria after previously adequate urine flow should trigger an immediate check for catheter obstruction or displacement. Bloody urine can obstruct the Foley with clots, and sedation makes suprapubic discomfort or bladder fullness unreliable. Bedside bladder ultrasonography rapidly distinguishes a urine-filled bladder with failed drainage from an empty bladder due to reduced renal output; it can also help assess catheter position and function.
His preserved blood pressure, clean incision, and absence of signs of active hemorrhage make immediate transfusion or re-exploration inappropriate. Pelvic fractures plus hematuria raise concern for bladder injury, but the first step for sudden postoperative oliguria is to exclude a simple mechanical drainage problem. A distended bladder would prompt catheter inspection, irrigation, or replacement.
- A) CT cystography is used when bladder rupture requires definitive evaluation; routine CT abdomen and pelvis is not the immediate test for abrupt cessation of catheter drainage in a stable patient.
- B) Repeat exploration is reserved for evidence of ongoing intra-abdominal bleeding, peritonitis, anastomotic complication, or hemodynamic instability, none of which is present.
- C) Packed red blood cells are indicated for significant blood loss with anemia or impaired perfusion. Tachycardia alone, with normal blood pressure and no other evidence of hemorrhagic shock, is insufficient.
Educational objective: When postoperative urine output suddenly falls, first exclude catheter kinking, displacement, or clot obstruction. Bedside bladder ultrasound distinguishes retained urine from genuinely reduced renal production.
Item 82 — Premature closure [Quality & Safety]
Answer: D — Premature closure
The physician accepted gastroenteritis before verifying that it adequately explained the patient’s presentation. Fever, persistent abdominal pain, vomiting, and tachycardia warranted a complete abdominal examination and consideration of a surgical abdomen; instead, the diagnostic process stopped after an incomplete examination.
The four preceding cases made gastroenteritis readily available mentally, but availability bias explains why that diagnosis came to mind—not the final error. Premature closure occurred when the physician committed to it without seeking disconfirming findings or accounting for the limitations of examining the patient in her wheelchair. The missed volvulus progressed to bowel ischemia and shock.
- A) Latent error: This is a concealed defect within a system that predisposes to future errors, such as poor equipment design or an unsafe workflow. Here, the immediate failure was premature termination of diagnostic reasoning.
- B) Near miss: A near miss is intercepted before causing patient harm. This patient developed necrotic bowel, shock, and required emergency resection.
- C) Non-preventable error: A proper examination and continued evaluation of a surgical cause could have prevented or reduced the diagnostic delay.
- E) Systems failure: Inadequate facilities for examining a wheelchair user may have contributed, but the described diagnostic error was accepting gastroenteritis without adequate verification.
Educational objective: Remember: premature closure is accepting a diagnosis before it has been adequately verified. When the working diagnosis does not account for every important finding—or the examination is incomplete—keep the differential open.
Item 83 — Mirtazapine [Psychiatry]
Answer: E — Mirtazapine
One month of depressed mood, anhedonia, insomnia, fatigue, and impaired concentration establishes a major depressive episode. Mirtazapine treats the depression while its strong H1-antihistaminic effect improves prominent sleep-onset insomnia.
It increases noradrenergic and serotonergic neurotransmission through central presynaptic α2-receptor antagonism and blocks postsynaptic 5-HT2 and 5-HT3 receptors. Sedation and increased appetite are characteristic adverse effects; here, the sedating effect is therapeutically useful. His epilepsy is the crucial comorbidity that makes bupropion inappropriate because it lowers the seizure threshold.
- A) Alprazolam may rapidly relieve acute anxiety or insomnia, but it does not treat the underlying major depressive episode and carries risks of tolerance and dependence.
- B) Aripiprazole is used for psychotic disorders, bipolar mania, or augmentation of treatment-resistant depression. There are no psychotic or manic features, and first-line antidepressant monotherapy has not yet been attempted.
- C) Bupropion is activating and can help depression with fatigue, but it increases seizure risk and is contraindicated in a patient with epilepsy.
- D) Buspirone is primarily used for generalized anxiety disorder and may augment an antidepressant after an inadequate response. It is not appropriate monotherapy for this depressive episode.
Educational objective: When depression is accompanied by prominent insomnia, consider mirtazapine and use its H1-mediated sedation therapeutically. Remember: avoid bupropion in patients with epilepsy because it lowers the seizure threshold.
Item 84 — Female factor infertility [Obstetrics & Gynecology]
Answer: A — Female factor infertility
The HSG shows contrast filling the uterine cavity without opacification or peritoneal spill from either fallopian tube, indicating bilateral tubal obstruction. Without tubal patency, sperm and oocyte cannot meet, so spontaneous conception is unlikely.
Her regular 28-day cycles and mittelschmerz support ongoing ovulation, making persistent suppression from prior depot medroxyprogesterone an inadequate explanation. The major risks are prior PID and ruptured appendicitis: PID causes endosalpingeal scarring, while pelvic inflammation and surgery can produce peritubal adhesions. Bilateral tubal disease therefore accounts for her infertility despite normal cycles and intercourse timing.
- B) Hydatidiform mole requires conception and abnormal trophoblastic proliferation. Bilateral tubal obstruction prevents the fertilization pathway rather than predisposing to molar pregnancy.
- C) Recurrent spontaneous abortions suggest impaired maintenance of established pregnancies, such as from uterine, genetic, endocrine, or antiphospholipid causes. This patient’s problem is failure to conceive.
- D) Successful spontaneous pregnancy within the next year is unlikely because bilateral tubal obstruction persists without treatment. IVF can bypass diseased tubes.
Educational objective: When HSG shows uterine filling but no tubal opacification or peritoneal spill, think bilateral tubal-factor infertility. Prior PID and pelvic inflammation or surgery are major causes.
Item 85 — Ductal carcinoma in situ [Heme/Onc]
Answer: A — Ductal carcinoma in situ
A tight cluster of pleomorphic microcalcifications in an asymptomatic woman is ductal carcinoma in situ. The decisive features are clustering within a small area and variation in calcification size and shape; these are malignant mammographic characteristics, unlike scattered or characteristically coarse benign calcifications.
DCIS is commonly detected on screening mammography before a mass becomes palpable. In high-grade lesions, intraductal necrotic debris calcifies, producing granular, linear, rod-shaped, or branching calcifications along the ductal system. Tissue diagnosis is obtained with image-guided core biopsy.
- B) Fat necrosis is associated with trauma or surgery and typically produces rim-like “eggshell” calcification or an oil cyst, not a compact pleomorphic cluster.
- C) An involuting fibroadenoma develops coarse, dense “popcorn” calcifications and may present as a circumscribed mass.
- D) Mastitis causes a painful, erythematous, warm breast, often with fever; this patient has neither inflammatory symptoms nor examination findings.
- E) Sclerosing adenosis may mimic carcinoma and can contain calcifications, but a localized cluster of numerous pleomorphic microcalcifications should be treated as DCIS until biopsy proves otherwise.
Educational objective: When screening mammography shows clustered pleomorphic, linear, or branching microcalcifications, think DCIS. Benign calcification patterns are more often coarse, rim-like, vascular, or diffusely scattered.
Item 86 — Diagnosis-driven reminders in patient charts [Quality & Safety]
Answer: B — Diagnosis-driven reminders in patient charts
A diagnosis-linked chart reminder improves adherence because it identifies the eligible patient and prompts the required action at the point of care. When a patient with asthma is due for annual pulmonary function testing, the reminder converts a general guideline into a patient-specific, immediately actionable task.
Electronic health record reminder systems are particularly useful for promoting guideline adherence and preventive services. Unlike delayed feedback or passive education, they integrate the standard directly into the clinician’s workflow.
- A) Audit and feedback can improve performance, but annual chart review is delayed and disconnected from the visit when testing should be ordered. Feedback works better when individualized and temporally close to the clinical event.
- C) Waiting-room flyers rely on patients to recognize the indication and request testing. They are less effective than clinician-facing, patient-specific prompts.
- D) Testing every patient with respiratory symptoms is not diagnosis-driven and would produce substantial unnecessary testing without specifically improving annual surveillance in established asthma.
- E) Restricting testing to examinations after exacerbations misses stable patients who are due for annual assessment and may also duplicate testing unnecessarily.
Educational objective: When adherence to a defined guideline is low, use patient-specific reminders embedded at the point of care. Diagnosis-driven chart prompts outperform passive education and delayed, nonspecific feedback.
Item 87 — Dicloxacillin therapy [Obstetrics & Gynecology]
Answer: B — Dicloxacillin therapy
Fever plus a tender, wedge-shaped area of unilateral breast erythema in a woman 3 weeks postpartum is acute lactational mastitis. Poor latch causes incomplete emptying and milk stasis, facilitating infection—usually by Staphylococcus aureus.
The next step is an oral antistaphylococcal penicillin such as dicloxacillin. Breastfeeding should continue with correction of attachment and regular emptying of the affected breast; this relieves stasis and reduces progression to abscess. There is no fluctuant mass or documented fluid collection to justify drainage.
- A) A supportive bra may reduce discomfort, but a tight breast binder promotes milk stasis and does not treat the bacterial infection.
- C) Fluconazole treats Candida infection, which typically causes burning nipple pain with nipple or areolar changes rather than febrile, wedge-shaped breast cellulitis.
- D) Needle aspiration is reserved for a breast abscess demonstrated clinically or on ultrasonography. This patient has cellulitic mastitis without a fluctuant collection.
- E) Untreated mastitis can progress to a breast abscess; fever and focal inflammatory changes require antibiotic therapy.
Educational objective: When a lactating woman develops fever with unilateral, wedge-shaped breast erythema and tenderness, think lactational mastitis and treat with an antistaphylococcal antibiotic while continuing effective breast emptying.
Item 88 — No additional diagnostic steps are indicated [Endocrine]
Answer: E — No additional diagnostic steps are indicated
At age 12, Tanner stage I breast and pubic hair development can still represent normal variation. Delayed puberty in girls is evaluated when breast development has not begun by age 13; absence of menarche alone is not concerning before age 15 or within 3 years of thelarche.
She is healthy, has no systemic or neurologic symptoms, and has an acceptable height percentile without evidence of growth failure. The appropriate approach is routine observation with reassessment of pubertal progression, not immediate endocrine testing or imaging.
- A) FSH and LH help distinguish primary gonadal failure from hypothalamic-pituitary causes after delayed puberty is established. She has not yet crossed the age threshold for evaluation.
- B) Thyroid testing is appropriate when growth failure or symptoms of hypothyroidism are present; random growth hormone measurement is not a useful screening test.
- C) Brain MRI is reserved for suspected central pathology, particularly with neurologic symptoms, pituitary hormone deficiencies, or confirmed hypogonadotropic hypogonadism.
- D) Bone age can help assess constitutional delay once delayed puberty or abnormal growth is identified. It is unnecessary in an asymptomatic 12-year-old with preserved stature.
Educational objective: Remember: absence of breast development by age 13 defines delayed puberty in girls. Before that threshold, an otherwise healthy girl with normal growth requires observation rather than laboratory testing or imaging.
Item 89 — No abnormalities [Endocrine]
Answer: E — No abnormalities
Marked hyperinsulinemia with hypoglycemia but suppressed C-peptide indicates exogenous insulin administration, so there is no pancreatic tumor to visualize. At a glucose of 41 mg/dL, endogenous insulin secretion should be nearly shut off; a C-peptide of 0.5 ng/mL is therefore inappropriately low despite the laboratory “normal range.”
An insulinoma secretes endogenous insulin and C-peptide together; diagnostic endogenous hyperinsulinism requires C-peptide ≥0.6 ng/mL during symptomatic hypoglycemia. Her recurrent neuroglycopenia, relief after snacks, and weight gain reflect repeated insulin-mediated hypoglycemia, but the discordant insulin–C-peptide pattern identifies surreptitious insulin use.
- A) A metastatic duodenal neuroendocrine tumor, such as a gastrinoma, would cause an acid-hypersecretory syndrome rather than isolated hyperinsulinemic hypoglycemia with suppressed C-peptide.
- B) A pancreatic pseudocyst is usually associated with pancreatitis or trauma and does not produce this biochemical pattern.
- C) Pancreatic head adenocarcinoma typically causes biliary or pancreatic duct obstruction, often with jaundice and weight loss—not recurrent hypoglycemia with very high insulin.
- D) Insulinomas are small hypervascular pancreatic masses, but endogenous insulin secretion would raise C-peptide along with insulin.
Educational objective: During hypoglycemia, high insulin with low C-peptide means exogenous insulin; high insulin with elevated C-peptide means endogenous secretion from insulinoma or a secretagogue.
Item 90 — weekly structured briefings plus daily huddles [Quality & Safety]
Answer: A — weekly structured briefings plus daily huddles
A shared mental model requires the entire multidisciplinary team to receive the same patient-specific information and discuss it together. Structured briefings establish the diagnosis, prognosis, priorities, and care plan; daily huddles then update that model as new data emerge, allowing discrepancies to be recognized and the plan revised promptly.
This synchronous, team-wide communication also gives nurses, physicians, pharmacists, and other clinicians an opportunity to voice concerns openly. Documentation and protocols help, but neither substitutes for direct, recurring discussion in a dynamic ICU.
- B) Protocol education standardizes management of common illnesses but does not create a shared understanding of an individual patient’s evolving condition and goals.
- C) Separate conversations promote fragmented information and prevent team members from hearing, questioning, and integrating one another’s perspectives.
- D) A consistent intensivist team improves continuity, but continuity alone does not maintain a common mental model across the full multidisciplinary team.
- E) Disease-specific ICUs concentrate expertise but do not inherently provide structured communication or shared situational awareness.
Educational objective: When a multidisciplinary team needs a shared mental model, use recurring, structured, team-wide briefings and huddles. The communication must be patient-specific, synchronous, and open to input from every team member.
Item 91 — Ultrasonography of the kidneys and bladder [Renal]
Answer: D — Ultrasonography of the kidneys and bladder
A first febrile UTI in a 12-month-old warrants renal-bladder ultrasonography to screen for structural abnormalities such as hydronephrosis, obstruction, or abnormal renal anatomy. Fever ≥39°C without another source, pyuria, nitrites, and a catheter culture growing >100,000 CFU/mL of E coli establish a febrile UTI; because the organism is susceptible, trimethoprim-sulfamethoxazole should be continued.
Ultrasonography is the noninvasive initial imaging study. Voiding cystourethrography is reserved for recurrent febrile UTIs or an abnormal ultrasound suggesting high-grade vesicoureteral reflux or obstructive pathology.
- A) Ciprofloxacin prophylaxis is not indicated after a single uncomplicated UTI and unnecessarily exposes the child to prolonged broad-spectrum therapy.
- B) Clindamycin has poor gram-negative urinary coverage and no role in prophylaxis against E coli UTI.
- C) CT urography adds radiation and contrast exposure. It is reserved for complicated infection, suspected abscess, or failure to improve—not routine evaluation after a first responsive UTI.
- E) Voiding cystourethrography directly evaluates vesicoureteral reflux but is invasive. It follows recurrent febrile infection or abnormal renal-bladder ultrasonography rather than being the first study here.
Educational objective: Remember: after a first febrile UTI in a young child, use renal-bladder ultrasonography as the initial structural study; reserve VCUG for recurrence or an abnormal ultrasound.
Item 92 — Azithromycin [Infectious Disease]
Answer: B — Azithromycin
Paroxysmal cough with posttussive vomiting after a mild catarrhal illness is pertussis. The normal temperature, oxygen saturation, and lung examination further argue against pneumonia.
A macrolide such as azithromycin is first-line therapy. It eradicates Bordetella pertussis from the nasopharynx and reduces transmission; symptom reduction is greatest when treatment begins during the early catarrhal phase, before the paroxysmal cough is established. His bilateral chest pain is mechanical pain from forceful coughing, not evidence of lower respiratory infection.
- A) Albuterol is appropriate for bronchospasm, which would present with wheezing or airflow limitation. His lungs are clear, and the posttussive emesis strongly favors pertussis.
- C) Levofloxacin can treat bacterial pneumonia or selected cases of bacterial sinusitis, neither of which fits this afebrile patient with a normal pulmonary examination.
- D) Omeprazole is used for reflux-associated chronic cough, typically without a preceding catarrhal phase or paroxysms causing posttussive vomiting.
- E) Prednisone may be used for significant asthma exacerbations but has no routine role in uncomplicated pertussis.
Educational objective: When you see a prolonged paroxysmal cough with posttussive vomiting after a mild upper respiratory prodrome, think pertussis and treat with a macrolide to reduce transmission.
Item 93 — Sputum culture [Respiratory]
Answer: D — Sputum culture
A cystic fibrosis exacerbation with copious purulent sputum, hypoxemia, leukocytosis, and new consolidations requires sputum culture alongside empiric broad-spectrum antibiotics. CF airways commonly harbor resistant and polymicrobial flora, particularly Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia cepacia complex, and other gram-negative organisms. Culture identifies the current pathogen and provides susceptibility data for subsequent antibiotic tailoring.
She is already producing abundant sputum, making sampling rapid and noninvasive. Antibiotics should not be delayed while awaiting results, but the specimen should be collected as early as possible because prior therapy can reduce culture yield.
- A) CT angiography evaluates pulmonary embolism. Her purulent sputum, fever, leukocytosis, and bilateral consolidations support an infectious pulmonary exacerbation rather than thromboembolism.
- B) Serum immunoglobulins are used when evaluating an unexplained cause of bronchiectasis or recurrent infection. Her bronchiectasis already has an established cause—cystic fibrosis.
- C) Spirometry helps monitor baseline disease and response to treatment, but it does not identify the pathogen driving this acute exacerbation and may be difficult during respiratory distress.
- E) Transbronchial biopsy is reserved for selected diffuse, infiltrative, or otherwise unexplained pulmonary disorders. An expectorated sputum sample provides the necessary microbiologic evaluation without invasive testing.
Educational objective: When a patient with cystic fibrosis develops increased sputum volume and purulence with systemic or respiratory deterioration, obtain a sputum culture promptly and begin empiric antipseudomonal coverage; use culture and susceptibility results to refine therapy.
Item 94 — weight bearing as tolerated, with no further workup [Musculoskeletal]
Answer: E — weight bearing as tolerated, with no further workup
Stable metaphyseal osteochondromas on serial radiographs plus an uncomplicated knee injury require neither biopsy nor MRI. The EXT1 mutation and multiple exostoses establish hereditary multiple osteochondromas; these lesions enlarge during growth and usually stop at physeal closure. His lesions are unchanged over 6 months, and there is no night pain, enlarging mass, neurologic deficit, or other feature suggesting malignant transformation or local compression.
He can bear weight, and examination shows no effusion or instability; the radiograph shows no acute fracture. Weight bearing as tolerated is therefore appropriate for the traumatic knee pain. The hereditary disorder warrants longitudinal orthopedic care during growth, but these stable knee lesions need no additional acute workup.
- A) Biopsy is reserved for an indeterminate or suspicious lesion. Stable osteochondromas with characteristic radiographic findings do not require tissue diagnosis.
- B) Neither biopsy nor non–weight bearing is justified without suspicious tumor features or an acute structural injury.
- C) MRI helps evaluate concerning symptoms, neurovascular compression, or cartilage-cap abnormalities. None is present here.
- D) There is no indication for MRI, and the absence of fracture or instability permits weight bearing.
- F) Non–weight bearing is appropriate for fractures or unstable injuries, not a patient who can bear weight with a stable examination and radiograph.
Educational objective: A radiographically characteristic osteochondroma that is stable and lacks night pain, progressive growth, or compressive symptoms does not require biopsy or local MRI. After minor trauma without fracture or instability, allow weight bearing as tolerated.
Item 95 — Diverticulosis [Gastrointestinal]
Answer: C — Diverticulosis
Abrupt, painless, bright-red hematochezia in a hemodynamically stable patient older than 60 years is diverticular bleeding. A penetrating artery at the base of a colonic diverticulum can rupture, producing intermittent, sometimes impressive bleeding without mucosal inflammation or abdominal tenderness.
Her age and daily NSAID use strengthen the diagnosis; NSAIDs increase the risk of diverticular hemorrhage. The absence of orthostatic hypotension, tachycardia, or hypovolemia indicates that the current bleeding is not hemodynamically significant. Colonoscopy is still required to localize the source and exclude malignancy, vascular ectasia, and colitis, but the presentation itself favors diverticulosis.
- A) Anal fissure causes sharp pain during defecation with a small amount of bright-red blood on stool or toilet paper. Recurrent bloody stools without anorectal pain do not fit.
- B) Colonic polyps generally cause occult or low-grade intermittent bleeding rather than abrupt, substantial hematochezia. A normal colonoscopy 8 years ago does not exclude a new lesion, but the bleeding pattern favors diverticulosis.
- D) Duodenal ulcer bleeding usually presents with melena. Hematochezia occurs only with brisk upper gastrointestinal hemorrhage, typically accompanied by hemodynamic instability.
- E) Gastritis more often causes occult bleeding, hematemesis, or melena, not isolated bright-red rectal bleeding.
- F) Ulcerative colitis produces recurrent bloody diarrhea with urgency and inflammatory symptoms rather than isolated, painless episodes beginning at age 70.
Educational objective: When an older adult develops abrupt, painless, sometimes large-volume hematochezia, think diverticular bleeding. Pain suggests an inflammatory or ischemic colonic process; minor painful bleeding suggests an anal fissure.
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Item 96 — Normal development [Psychiatry]
Answer: E — Normal development
Peer-group identification, increased privacy, emotional distance from parents, and testing parental limits are expected during adolescence. His behavioral change began after joining a new peer group, while examination, substance screening, and overall functioning remain unremarkable.
Repeated trespassing is inappropriate but does not by itself establish conduct disorder. That diagnosis requires a persistent pattern with at least 3 specified behaviors over 12 months, including at least 1 within the past 6 months. Here, there is no broader pattern of aggression, property destruction, deceit or theft, or serious rule violations.
- A) Adjustment disorder requires emotional or behavioral symptoms in response to an identifiable psychosocial stressor, with clinically significant distress or impairment. No precipitating stressor is described.
- B) ADHD begins in childhood and causes persistent inattention and/or hyperactivity-impulsivity across multiple settings. Neither the history nor his current functioning supports this pattern.
- C) Conduct disorder involves recurrent violation of others’ rights or major societal norms across multiple behavioral domains. One type of peer-associated delinquent behavior is insufficient.
- D) Oppositional defiant disorder requires a sustained, impairing pattern of angry, argumentative, defiant, or vindictive behavior. Curfew disputes and irritability confined to the parent-adolescent relationship are developmentally common.
Educational objective: When an adolescent develops stronger peer affiliation, greater privacy, and mild limit-testing without pervasive dysfunction or a qualifying pattern of misconduct, think normal development rather than a disruptive behavior disorder.
Item 97 — CT scan of the abdomen and pelvis [Renal]
Answer: B — CT scan of the abdomen and pelvis
Acute colicky flank pain, vomiting, marked hematuria, and unilateral hydroureteronephrosis indicate an obstructing ureteral calculus. Ultrasonography has identified the obstruction but not its cause or level; the next study is a noncontrast, low-dose CT of the abdomen and pelvis.
CT is the most accurate test for urinary calculi and defines the stone’s size and location—information that determines whether spontaneous passage or intervention is appropriate. The hydroureter extending to the bladder favors a distal ureteral obstruction rather than ureteropelvic junction obstruction. The mild pyuria does not establish UTI in an afebrile child with negative nitrites and a renal-colic presentation.
- A) Captopril renography evaluates renovascular hypertension by demonstrating functionally significant renal artery stenosis. It has no role in acute obstructive renal colic.
- C) MAG-3 diuretic renography assesses drainage and differential renal function in suspected ureteropelvic junction obstruction. UPJ obstruction dilates the renal pelvis without hydroureter extending to the bladder.
- D) Radionuclide cystography detects vesicoureteral reflux with relatively low radiation exposure, often during follow-up. It does not localize a ureteral calculus.
- E) Retrograde pyelography is invasive and reserved for selected cases requiring detailed collecting-system evaluation or endoscopic intervention. It is not the next diagnostic study here.
- F) Spinal ultrasonography evaluates occult spinal dysraphism in young infants with suggestive cutaneous or neurologic findings. This child has an acute mechanical urinary obstruction.
- G) Voiding cystourethrography evaluates vesicoureteral reflux and posterior urethral valves, typically in the setting of recurrent febrile UTI or appropriate urinary tract abnormalities. The presentation instead indicates ureteral stone disease.
Educational objective: When renal colic and hematuria persist despite an ultrasound that shows hydronephrosis but does not identify the stone, obtain a low-dose noncontrast CT to define stone size, location, and obstruction.
Item 98 — Hypersensitivity pneumonitis [Respiratory]
Answer: C — Hypersensitivity pneumonitis
Organic wood-dust exposure followed by subacute cough, exertional dyspnea, fatigue, weight loss, diffuse crackles, and reticulonodular infiltrates is hypersensitivity pneumonitis. Inhaled antigens at the lumber mill trigger immune-mediated inflammation involving both alveoli/interstitium and small airways. That dual involvement explains the mixed restrictive-obstructive pulmonary function pattern: restriction from alveolar-interstitial disease and obstruction from bronchiolar inflammation with air trapping.
The temporal relationship to a new occupational exposure is the decisive clue. Subacute disease can evolve over weeks to months and produce constitutional symptoms without the abrupt febrile episodes associated with acute exposure. Upper-lung predominance and relative basal sparing may occur, particularly as fibrosis develops.
- A) Aspergillosis: Allergic bronchopulmonary aspergillosis occurs in patients with asthma but typically causes recurrent wheezing, eosinophilia, markedly elevated IgE, mucus plugging, and central bronchiectasis—not this occupational interstitial syndrome.
- B) Asthma recurrence: Asthma causes episodic wheezing and reversible airflow obstruction. It does not account for crackles, weight loss, restrictive physiology, or reticulonodular infiltrates.
- D) Sarcoidosis: Sarcoidosis can affect young African American adults, but bilateral hilar adenopathy, extrapulmonary findings, and well-formed noncaseating granulomas would support it. The exposure-linked presentation favors hypersensitivity pneumonitis.
- E) Silicosis: Silicosis produces upper-lobe nodules after substantial crystalline silica exposure, usually with a longer latency. Feeding logs into a saw primarily creates organic wood dust rather than silica exposure.
Educational objective: When respiratory and constitutional symptoms follow an organic occupational exposure, especially with crackles, interstitial opacities, and mixed restrictive-obstructive physiology, think hypersensitivity pneumonitis.
Item 99 — Cognitive behavioral therapy [Psychiatry]
Answer: A — Cognitive behavioral therapy
Prolonged bilateral shaking with side-to-side head movements, forced eye closure, crying, fluctuating responsiveness, and no ictal EEG correlate establishes psychogenic nonepileptic seizures (PNES), a functional neurologic disorder. The history of childhood trauma adds a common psychosocial association, while failure of multiple antiseizure drugs reflects treatment of the wrong mechanism rather than refractory epilepsy.
Management begins with a clear, nonjudgmental explanation that the events are real but are not caused by epileptic cortical discharges, followed by psychiatric assessment and cognitive behavioral therapy. CBT helps identify stressors, modify maladaptive responses, and develop effective coping strategies. Antiseizure medications should be withdrawn gradually under neurologic supervision once coexisting epilepsy has been excluded.
- B) Hypnosis may be used selectively in chronic conversion symptoms, but it is not the preferred first-line psychotherapy for PNES.
- C) Increasing pregabalin will not treat events without an epileptic EEG correlate and only adds medication toxicity.
- D) Psychoanalytic therapy is prolonged and insight-oriented; CBT has a more direct role in reducing functional seizure frequency and improving coping.
- E) Epilepsy surgery requires a localized epileptogenic focus producing electroclinical seizures. Her captured typical events have no ictal EEG activity.
Educational objective: When prolonged, fluctuating seizure-like episodes feature eye closure, side-to-side head movement, intermittent responsiveness, and no ictal change on video EEG, think PNES. Treat with empathetic diagnostic disclosure, psychiatric evaluation, and CBT—not escalation of antiseizure therapy.
Item 100 — Lymphopenia [Immunology]
Answer: C — Lymphopenia
Cleft palate, congenital cardiac defect, recurrent sinopulmonary infections, and an absent thymic shadow on chest x-ray identify 22q11.2 deletion syndrome (DiGeorge syndrome). Abnormal development of the third and fourth pharyngeal pouches causes thymic hypoplasia or aplasia, impairing T-cell maturation.
The expected leukocyte abnormality is therefore a reduced absolute lymphocyte count, driven predominantly by decreased CD3+ T cells. Partial thymic hypoplasia usually produces moderate lymphopenia, whereas complete thymic aplasia causes profound T-cell deficiency. B-cell numbers and immunoglobulin levels may initially remain relatively preserved.
- A) Eosinophilia fits allergic disease, parasitic infection, hyper-IgE syndrome, or Omenn syndrome. Omenn syndrome would typically include erythroderma, alopecia, hepatosplenomegaly, and failure to thrive rather than palatal and cardiac malformations.
- B) Lymphocytosis may be physiologic in young children or occur with viral infections. Thymic hypoplasia instead reduces circulating mature T lymphocytes.
- D) Neutropenia suggests disorders such as severe congenital or cyclic neutropenia, which cause recurrent bacterial infections without the characteristic palatal, cardiac, and thymic abnormalities.
- E) Neutrophilia accompanies acute bacterial infection or inflammation. This child is currently afebrile with clear lungs, and it would not explain the absent thymic shadow.
Educational objective: When cleft palate and congenital cardiac disease occur with recurrent infections and an absent thymic shadow, think 22q11.2 deletion syndrome. Thymic hypoplasia causes deficient T-cell maturation and lymphopenia.
Item 101 — Administration of Rho(D) immune globulin [Obstetrics & Gynecology]
Answer: C — Administration of Rho(D) immune globulin
An Rh-negative, unsensitized woman at 28 weeks should receive routine antenatal Rho(D) immune globulin. The positive antibody screen with an anti-D titer too weak to measure represents residual passive anti-D from the dose given after bleeding at 18 weeks, not clinically significant alloimmunization.
Anti-D administered for an earlier sensitizing event does not replace routine 28-week prophylaxis; its half-life is only about 16–24 days. A standard 300-µg dose at 28 weeks protects against otherwise silent third-trimester fetomaternal hemorrhage. She will also require postpartum anti-D within 72 hours if the neonate is Rh-positive.
- A) Repeat serum anti-D antibody titer is used to monitor established alloimmunization. An unmeasurably weak level following recent prophylaxis does not justify withholding the scheduled 28-week dose.
- B) Ultrasonography, particularly MCA Doppler, evaluates fetal anemia in a genuinely alloimmunized pregnancy. There is no significant maternal antibody titer or evidence of fetal compromise here.
- D) Amniocentesis is invasive and is not indicated for passive anti-D; fetal Rh genotyping and MCA Doppler have also largely replaced invasive testing in relevant cases.
- E) Induction at 28 weeks would expose a stable fetus to severe prematurity without an obstetric indication.
Educational objective: Remember: prior anti-D given for bleeding does not replace routine prophylaxis at 28 weeks. A very weak anti-D screen after Rho(D) immune globulin usually reflects passive antibody, whereas measurable or rising titers suggest true alloimmunization.
Item 102 — Flora [Dermatology]
Answer: B — Flora
Intensely pruritic vesicular lesions in linear streaks after a summer picnic are Rhus dermatitis from contact with poison ivy, poison oak, or poison sumac. The linear pattern records where urushiol-containing leaves brushed across the skin; involvement of the forearm, cheek, and ankle reflects separate exposed contact sites.
Urushiol causes T-cell–mediated delayed hypersensitivity, with dermatitis appearing 12–72 hours after exposure. Avoiding the offending flora—or promptly washing exposed skin, clothing, and pet fur—prevents the eruption. Vesicle fluid does not spread the rash.
- A) Dog fur can carry urushiol after contact with plants, but the animal itself is not the allergen. Avoiding the causative plants is the primary preventive measure.
- C) Peanut allergy causes immediate urticaria, angioedema, gastrointestinal symptoms, or anaphylaxis rather than linear vesicular dermatitis.
- D) Perfumed soap can cause irritant or allergic contact dermatitis, usually in areas repeatedly exposed during bathing; it does not explain linear streaks after a park visit.
- E) Photosensitive eruptions favor sun-exposed surfaces and are generally symmetric rather than linear or angular at discrete contact sites.
Educational objective: When you see intensely pruritic, linear vesicles after outdoor exposure, think urushiol-induced allergic contact dermatitis. The shape of the eruption often maps the plant’s contact with the skin.
Item 103 — Chronic myeloid leukemia [Heme/Onc]
Answer: D — Chronic myeloid leukemia
Marked leukocytosis with a full spectrum of granulocytic maturation, basophilia, eosinophilia, and splenomegaly is chronic-phase CML. The differential shows predominantly mature neutrophils with myelocytes and metamyelocytes rather than blast predominance; this preserved differentiation is the decisive feature separating chronic-phase CML from acute leukemia.
Her early satiety reflects splenic enlargement, while fatigue and malaise fit the insidious presentation. Diagnosis is confirmed by demonstrating the BCR::ABL1 fusion arising from t(9;22), using karyotyping, FISH, or PCR.
- A) Acute lymphocytic leukemia presents with lymphoblast proliferation, often accompanied by anemia and thrombocytopenia. This patient instead has granulocytic leukocytosis with multiple stages of myeloid maturation.
- B) Acute myeloid leukemia requires a blast-predominant process, typically with marrow failure and circulating myeloblasts. Here, mature neutrophils dominate and no blast excess is reported.
- C) Chronic lymphocytic leukemia produces sustained absolute lymphocytosis with small mature lymphocytes. Her lymphocyte proportion is only 2%, while the leukocytosis is overwhelmingly myeloid.
- E) Monoclonal gammopathy of undetermined significance is defined by an asymptomatic monoclonal protein without myeloma-defining organ damage. It does not explain marked neutrophilic leukocytosis, left shift, basophilia, and splenomegaly.
Educational objective: When marked leukocytosis includes granulocytes at several maturation stages plus basophilia and splenomegaly, think chronic-phase CML. Confirm it by demonstrating BCR::ABL1.
Item 104 — Pulmonary function testing [Respiratory]
Answer: E — Pulmonary function testing
A 50-pack-year smoking history plus progressive dyspnea, chronic cough, end-expiratory wheezing, and prolonged expiration is COPD until demonstrated otherwise. The next diagnostic step is spirometry, the initial pulmonary function test used to establish airflow obstruction.
COPD produces a reduced FEV1 and a reduced FEV1/FVC ratio; persistent post-bronchodilator obstruction supports the diagnosis. Lung volumes and DLCO can subsequently characterize hyperinflation and distinguish emphysema-predominant disease, but they are not required before spirometry.
- A) CT can define emphysema, bronchiectasis, interstitial disease, or a lung mass, but it does not establish the physiologic diagnosis of airflow obstruction and is not the first test here.
- B) Echocardiography is appropriate when heart failure, valvular disease, or pulmonary hypertension is suspected. The absence of orthopnea, jugular venous distention, and other congestive findings, together with obstructive pulmonary signs, favors a pulmonary evaluation first.
- C) Exercise stress testing evaluates suspected myocardial ischemia. She has no chest pain or other features making coronary ischemia the leading cause of her dyspnea.
- D) Tuberculosis evaluation fits chronic cough accompanied by epidemiologic risk or suggestive constitutional, radiographic, or hemoptysis findings. Her smoking history and obstructive examination are far more consistent with COPD.
Educational objective: When a long-term smoker has progressive dyspnea, chronic cough, wheezing, and prolonged expiration, obtain spirometry first. Remember: COPD is established physiologically by persistent airflow obstruction with a reduced FEV1/FVC ratio.
Item 105 — Buspirone [Psychiatry]
Answer: A — Buspirone
Six months of excessive financial and occupational worry with insomnia, fatigue, muscle tension, and feeling “edgy” is generalized anxiety disorder. Buspirone treats chronic anxiety without sedation, euphoria, tolerance, or dependence—decisive advantages in a patient with alcohol use disorder who is experiencing renewed cravings.
Buspirone is a 5-HT1A partial agonist and takes approximately 2–4 weeks for clinical benefit, so it is not suitable for immediate relief. Here, the sleep disturbance is part of the anxiety syndrome rather than isolated insomnia; treating the underlying anxiety is preferable to prescribing a hypnotic.
- B) Clonazepam rapidly reduces anxiety and is useful in panic disorder, but its dependence and sedative potential make it inappropriate in a patient with substance use history.
- C) Diphenhydramine may provide short-term sedation but does not treat generalized anxiety and causes anticholinergic adverse effects and tolerance.
- D) Imipramine can treat certain anxiety disorders, but its anticholinergic, cardiovascular, and overdose toxicity make it a poor choice here.
- E) Quetiapine may be used for treatment-resistant generalized anxiety disorder, not as initial therapy given its metabolic and sedative adverse effects.
- F) Temazepam is a benzodiazepine hypnotic. It neither addresses the daytime anxiety syndrome nor avoids the dependence risk relevant to this patient.
Educational objective: When chronic excessive worry is accompanied by tension, fatigue, and insomnia in a patient at risk for substance misuse, think buspirone: delayed-onset anxiolysis without abuse potential or dependence.
Item 106 — Parkinson disease [Neurology]
Answer: E — Parkinson disease
Dream enactment with punching, kicking, vocalization, and recall of a matching dream identifies REM sleep behavior disorder. The mechanism is loss of normal REM atonia, allowing dream-related motor activity to emerge.
In an older man without an offending medication or narcolepsy symptoms, isolated RBD is a strong prodromal marker of an α-synucleinopathy, particularly Parkinson disease. Constipation further supports early autonomic involvement that can precede bradykinesia, rigidity, and rest tremor by years.
- A) Alzheimer disease typically begins with progressive episodic memory impairment. RBD is linked more strongly to Lewy body disorders than to Alzheimer pathology.
- B) Amyotrophic lateral sclerosis causes progressive upper and lower motor neuron findings, not dream enactment from loss of REM atonia.
- C) Cerebral infarction is not the characteristic long-term neurologic association of isolated RBD; the stem also lacks focal neurologic deficits or an acute onset.
- D) Narcolepsy can include RBD, but would usually feature excessive daytime sleepiness, cataplexy, sleep paralysis, or hypnagogic hallucinations. Narcolepsy-associated RBD does not carry the same neurodegenerative risk.
Educational objective: When an older adult punches, kicks, or vocalizes while enacting recalled dreams, think REM sleep behavior disorder. Isolated RBD—especially with constipation or hyposmia—often precedes Parkinson disease and other α-synucleinopathies.
Item 107 — Contact adult protective services [Geriatrics]
Answer: C — Contact adult protective services
An unexplained fracture plus bruises at multiple sites in a dependent, nonverbal older adult raises immediate concern for elder abuse or neglect. Her poor hygiene and unkempt appearance add evidence of inadequate care; dementia and complete caregiver dependence make her especially vulnerable.
The fracture has been treated, but management cannot stop at the orthopedic injury. Suspected elder mistreatment must be reported to adult protective services so the circumstances can be investigated and a safe disposition arranged. Proof of abuse is not required before reporting, and the clinician should not independently decide placement before the formal safety assessment.
- A) Hospital admission is appropriate for an acute medical indication or immediate safety needs, but it does not replace mandatory reporting and investigation.
- B) Nursing-facility placement may ultimately be recommended, but that decision follows assessment of the patient’s safety, needs, and available resources.
- D) Providing facility phone numbers shifts responsibility to the only caregiver, who may be involved in the suspected mistreatment, and does not protect the patient.
- E) A geriatric clinic can address dementia and long-term care needs, but outpatient referral is inadequate when current abuse or neglect is suspected.
Educational objective: When a vulnerable older adult has unexplained injuries, injuries at different sites, poor hygiene, or caregiver-dependent neglect, report suspected elder mistreatment to adult protective services after addressing immediate medical needs. Suspicion—not definitive proof—is sufficient to report.
Item 108 — Methamphetamine [Psychiatry]
Answer: D — Methamphetamine
Severe gingival disease in a young adult with stimulant-associated cardiomyopathy is the signature combination of chronic methamphetamine use. His orthopnea, pulmonary crackles, S3, and dependent edema establish decompensated heart failure; the preceding exertional chest pressure suggests stimulant-induced myocardial ischemia.
Methamphetamine releases dopamine and other biogenic amines while impairing their reuptake and metabolism. Sustained catecholaminergic stimulation produces hypertension, tachycardia, coronary vasoconstriction and microvascular ischemia, eventually causing dilated cardiomyopathy. Chronic use also causes severe gingival recession and dental decay—often termed “meth mouth”—which is the decisive clue separating it from other cardiotoxic stimulants.
- A) Cocaine can cause myocardial ischemia, hypertension, arrhythmias, and chronic cardiomyopathy, but severe destructive gingival and dental disease favors methamphetamine use.
- B) Heroin causes miosis and respiratory/CNS depression; intravenous use also raises concern for right-sided infective endocarditis, not this stimulant-associated dental and cardiovascular pattern.
- C) Methadone is associated with respiratory depression and QT prolongation with torsades de pointes. It does not produce the characteristic gingival destruction or chronic sympathomimetic syndrome.
- E) Toluene inhalation causes CNS toxicity, renal tubular acidosis, hypokalemia, and arrhythmias. Severe gingivitis with catecholamine-mediated cardiomyopathy is not its typical presentation.
Educational objective: When a young patient has unexplained cardiomyopathy plus severe gingival recession or dental decay, think chronic methamphetamine use. Methamphetamine’s sustained catecholamine effects cause hypertension, ischemia, arrhythmias, and toxic cardiomyopathy.
Item 109 — plasma and urinary catecholamines and metanephrines [Endocrine]
Answer: D — plasma and urinary catecholamines and metanephrines
Episodic headache, palpitations, sweating, severe hypertension, and an adrenal mass = pheochromocytoma until biochemical evaluation proves otherwise. The next step is documentation of catecholamine excess, preferably with plasma free metanephrines or 24-hour urinary fractionated metanephrines; catecholamine levels may fluctuate between attacks, whereas intratumoral metabolism produces a more continuous release of metanephrines.
The CT has already localized the adrenal lesion, but imaging alone cannot establish that it is functional. Biochemical confirmation must precede operative management, followed by appropriate preoperative alpha-adrenergic blockade before adrenalectomy.
- A) Vanillylmandelic acid is less sensitive than fractionated metanephrines. Urinary 5-HIAA evaluates carcinoid syndrome, which typically causes flushing and diarrhea rather than this hypertensive adrenergic triad.
- B) Adrenal venous sampling is used mainly to lateralize aldosterone secretion in confirmed primary aldosteronism; it is unnecessary when evaluating suspected pheochromocytoma.
- C) Immediate adrenalectomy risks a catecholamine-induced hypertensive crisis without biochemical confirmation and preoperative preparation. Routine biopsy of the contralateral adrenal gland is not indicated.
- E) Transsphenoidal hypophysectomy treats selected pituitary tumors, not a catecholamine-secreting adrenal medullary tumor.
Educational objective: When episodic headache, palpitations, sweating, and hypertension accompany an adrenal mass, first confirm pheochromocytoma biochemically with plasma free or urinary fractionated metanephrines before proceeding to surgery.
Item 110 — Abstinence from alcoholic beverages [Gastrointestinal]
Answer: A — Abstinence from alcoholic beverages
Recurrent pancreatitis plus alcohol use disorder makes continued alcohol exposure the major modifiable driver of readmission. Alcohol can promote pancreatic injury through acinar-cell toxicity, premature intracellular enzyme activation, protein-rich secretions, and small-duct obstruction. Continued exposure also accelerates progression toward pancreatic fibrosis and calcification.
The discharge intervention with the greatest direct impact is sustained abstinence, supported by motivational interviewing, addiction treatment, relapse-prevention counseling, and ongoing follow-up. Housing and insurance barriers matter, but addressing them without removing the etiologic exposure will not reduce recurrence as effectively.
- B) Health insurance may improve access to outpatient care and addiction services, but it does not itself remove the cause of recurrent pancreatitis.
- C) Nutritional counseling is useful when malnutrition, hypertriglyceridemia, or chronic pancreatic insufficiency is present. It is secondary to alcohol cessation in this patient.
- D) Shelter placement may improve safety and continuity of care, but housing alone does not address the pancreatic insult driving repeated admissions.
Educational objective: When recurrent acute pancreatitis occurs in a patient with alcohol use disorder, prioritize sustained alcohol abstinence as the most effective strategy to prevent further attacks and progression to chronic pancreatitis.
Item 111 — Heat avoidance [Dermatology]
Answer: B — Heat avoidance
Superficial, clear, noninflammatory vesicles that rupture with minimal pressure in hot, humid weather identify miliaria crystallina. Sweat duct obstruction with rupture just beneath the stratum corneum produces the characteristic “water-droplet” appearance; the absence of surrounding erythema separates it from miliaria rubra and infectious vesicular eruptions.
Cooling is the treatment: avoid heat and humidity, reduce sweating, remove excessive clothing, and use an air-conditioned environment when available. Topical preparations are generally unnecessary and may worsen ductal occlusion.
- A) Antifungal cream treats superficial fungal infections such as candidiasis or dermatophytosis, which produce erythematous, scaly, or intertriginous lesions rather than fragile clear vesicles.
- C) Oral antibiotics are reserved for bacterial infection. There is no erythema, purulence, crusting, or systemic illness here.
- D) Viral vesicles are typically inflammatory and occur in recognizable patterns, such as crops in varicella or a painful dermatomal distribution in herpes zoster.
- E) Oral retinoids are used for selected severe keratinization disorders and acne, not acute sweat-duct obstruction.
- F) Ultraviolet therapy has no role in miliaria and adds unnecessary heat exposure.
Educational objective: When hot, humid conditions produce tiny, clear, easily ruptured vesicles without erythema, think miliaria crystallina. Management is environmental cooling and avoidance of sweating.
Item 112 — it roughly doubles her risk of death over 3 months [Psychiatry]
Answer: B — it roughly doubles her risk of death over 3 months
Post–myocardial infarction depression is an independent marker of increased short-term cardiac morbidity and mortality, not merely reduced emotional well-being. Her depressed mood, anhedonia, neurovegetative symptoms, and declining rehabilitation attendance identify clinically significant post-MI depression.
Several pathways contribute: reduced adherence to rehabilitation and secondary prevention, decreased heart-rate variability from impaired parasympathetic activity, greater platelet activation, and increased susceptibility to ventricular arrhythmias and recurrent ischemic events. Thus, depression after MI is associated with an approximately twofold increase in near-term mortality.
- A) Depression does reduce perceived quality of life, but its impact extends to cardiac outcomes and mortality after MI.
- C) Reduced activity and social engagement do not protect against ischemia. Withdrawal from rehabilitation and poorer adherence instead worsen cardiovascular risk.
- D) Depression has important physical consequences in coronary artery disease, including impaired rehabilitation, greater medical morbidity, and increased mortality.
Educational objective: When depressive symptoms develop after myocardial infarction, think increased short-term cardiac mortality—not an isolated quality-of-life problem. Reduced treatment adherence, autonomic dysfunction, platelet activation, and arrhythmic risk link depression to adverse outcomes.
Repeating themes across blocks? The topics that recur exam after exam are collected in Step 2 CK chronic repeats.
Item 113 — Zenker diverticulum [Gastrointestinal]
Answer: D — Zenker diverticulum
An elderly man with chronic dysphagia, delayed regurgitation of undigested food and liquids, and aspiration pneumonia has a Zenker diverticulum. Food and saliva collect in the pharyngeal pouch and may return hours after swallowing, particularly when supine, creating a major aspiration risk.
Zenker diverticulum is a false pulsion diverticulum formed by herniation of mucosa and submucosa through Killian dehiscence, just above the cricopharyngeus. Impaired upper esophageal sphincter opening increases hypopharyngeal pressure and drives pouch formation. The patient’s age and particulate regurgitation distinguish it from distal esophageal disorders.
- A) Achalasia causes dysphagia to both solids and liquids with retained esophageal contents and may cause nocturnal regurgitation. The strongly suggestive combination of advanced age, delayed particulate regurgitation, and aspiration favors a pharyngeal pouch.
- B) Esophageal cancer typically causes rapidly progressive dysphagia, initially to solids and later to liquids, often with weight loss. A stable intermittent course over 5 years argues against malignancy.
- C) Hiatal hernia commonly presents with gastroesophageal reflux symptoms rather than retention and regurgitation of undigested food; antacids may improve associated heartburn.
Educational objective: When an older patient has dysphagia, delayed regurgitation of undigested food, halitosis, or recurrent aspiration, think Zenker diverticulum. It is a false pulsion diverticulum through Killian dehiscence above the cricopharyngeus.
Item 114 — Observation only [Obstetrics & Gynecology]
Answer: E — Observation only
A small functional ovarian cyst with minor leakage of fluid requires observation because she is hemodynamically stable and has no evidence of torsion, infection, ectopic pregnancy, or significant hemorrhage.
The timing in the latter half of a regular cycle, mild unilateral pain, 3 × 4-cm adnexal cyst, and small volume of pelvic free fluid fit a functional cyst with limited rupture or leakage. Functional cysts of this size usually regress spontaneously. Acute surgery is reserved for severe pain, hemodynamic instability, ongoing intraperitoneal bleeding, suspected torsion, or concerning cyst morphology. Follow-up ultrasonography can document resolution if symptoms persist.
- A) Antibiotic therapy is indicated for pelvic inflammatory disease, which would be supported by cervical motion tenderness, mucopurulent discharge, fever, or infectious risk findings—not an isolated small ovarian cyst.
- B) Appendectomy does not fit left-sided adnexal tenderness with an ovarian cyst demonstrated on ultrasonography.
- C) Aspiration is unnecessary for a small functional cyst and risks recurrence, infection, and spillage if the lesion is neoplastic.
- D) Laparoscopy is appropriate for suspected torsion, uncontrolled hemorrhage, or a persistent or suspicious mass. Her mild symptoms and stable vital signs do not justify surgery.
Educational objective: When a reproductive-age woman has mild unilateral pelvic pain, a small simple adnexal cyst, minimal free fluid, and stable vital signs, think functional ovarian cyst and manage conservatively. Severe pain, instability, or torsion findings shift management toward urgent laparoscopy.
Item 115 — nothing further is needed at this time [ENT & Ophthalmology]
Answer: E — nothing further is needed at this time
Asymptomatic cerumen with normal hearing requires no intervention. Cerumen is physiologic: it lubricates the external canal, traps foreign material, and provides bacteriostatic and fungistatic protection. It is normally expelled by epithelial migration and jaw movement.
This patient has no hearing impairment, ear fullness, tinnitus, pain, discharge, or abnormal external-ear findings. Therefore, the potential harms of unnecessary manipulation outweigh any benefit. This is particularly relevant in older adults, whose ear canals may be dry and fragile.
- A) Irrigation is unnecessary and should be avoided when tympanic membrane integrity cannot be established. It may also traumatize the fragile external canal in an older patient.
- B) Manual removal is appropriate for symptomatic or problematic impaction, but referral to an otorhinolaryngologist is not warranted for asymptomatic cerumen.
- C) Cotton swabs can push wax deeper, produce impaction, and traumatize the ear canal or tympanic membrane; they should not be recommended.
- D) Ceruminolytics are used to soften hard, impacted wax before removal. There is no indication to treat physiologic, asymptomatic cerumen here.
Educational objective: Remember: cerumen is protective, not inherently pathologic. Treat it when it causes symptoms or requires removal for a clinically necessary assessment; otherwise, leave it alone.
Item 116 — Pulmonary infarction [Respiratory]
Answer: H — Pulmonary infarction
Sudden pleuritic chest pain, hemoptysis, a pleural rub, and a peripheral wedge-shaped opacity define pulmonary infarction. The triangular pleural-based density is a Hampton hump, produced when a distal pulmonary arterial embolus causes ischemic necrosis with surrounding hemorrhage.
Her recent pelvic surgery, ovarian malignancy, and hospitalization create a strong thromboembolic setting despite prophylactic low-molecular-weight heparin. CT showing no embolus in the major pulmonary arteries does not exclude a small peripheral embolus, and negative leg ultrasonography does not exclude pulmonary embolism; the source may be pelvic, already embolized, or no longer detectable.
- A) Air embolism causes abrupt respiratory or neurologic compromise after vascular air entry, not a Hampton hump with pleuritic pain and hemoptysis.
- B) Empyema presents with fever, systemic toxicity, and infected pleural fluid rather than a wedge-shaped intraparenchymal opacity.
- C) Hemothorax produces pleural fluid, often after thoracic trauma or instrumentation; it does not produce a peripheral triangular pulmonary density.
- D) Pericarditis causes positional pleuritic pain and a pericardial friction rub, but neither hemoptysis nor a wedge-shaped lung opacity.
- E) Pneumonia usually causes air-space consolidation with infectious features such as fever and productive cough. The postoperative thrombotic risk and Hampton hump favor infarction.
- F) Pulmonary hemorrhage may surround an infarct, but isolated hemorrhage does not account as well for this abrupt pleuritic syndrome and characteristic peripheral wedge.
- G) Pulmonary hypertension causes progressive dyspnea, exertional symptoms, and right-heart findings rather than acute pleuritic pain with focal infarction.
Educational objective: When sudden pleuritic pain and hemoptysis accompany a peripheral pleural-based wedge-shaped opacity, think pulmonary infarction from a distal pulmonary embolus. A negative lower-extremity duplex or absence of central emboli does not exclude PE.
Item 117 — Ruptured abdominal aortic aneurysm [Cardiovascular]
Answer: D — Ruptured abdominal aortic aneurysm
Sudden severe abdominal pain with profound hypotension in an elderly male smoker is a ruptured abdominal aortic aneurysm. The abdominal radiograph shows a large curvilinear calcified outline of the aneurysm, while weak groin pulses and absent pedal pulses support advanced aortoiliac atherosclerotic disease.
Rupture causes massive retroperitoneal or intraperitoneal hemorrhage and requires immediate operative or endovascular repair. A palpable pulsatile mass may be difficult to detect in a patient with obesity and is not required for diagnosis. The near-normal hematocrit does not exclude acute hemorrhage because whole blood is lost initially; hematocrit falls after plasma redistribution or fluid administration.
- A) Acute pancreatitis produces epigastric pain, often radiating to the back, with elevated lipase or amylase. Normal amylase and the calcified aneurysmal outline argue against it.
- B) Mesenteric ischemia causes severe pain out of proportion to early abdominal findings, but the radiograph does not typically demonstrate a calcified aortic aneurysm. Shock usually reflects advanced bowel infarction.
- C) A perforated duodenal ulcer causes abrupt pain with peritoneal rigidity and free subdiaphragmatic air on an upright radiograph, neither of which is described.
- E) Small-bowel obstruction usually presents with colicky pain, vomiting, and dilated small-bowel loops with multiple air-fluid levels rather than hemorrhagic shock.
Educational objective: When an older smoker presents with sudden abdominal or back pain and hypotension, presume ruptured abdominal aortic aneurysm—especially if radiography shows a curvilinear calcified aortic outline. A normal initial hematocrit does not exclude acute major hemorrhage.
Item 118 — Neurogenic bladder [Neurology]
Answer: D — Neurogenic bladder
Myelomeningocele with lower-extremity paralysis strongly predicts neurogenic bladder because the spinal lesion disrupts the sacral pathways coordinating detrusor contraction and urethral sphincter relaxation. Dysfunction may appear as an atonic bladder, detrusor overactivity, poor compliance, or detrusor-sphincter dyssynergia; urinary dribbling is therefore not required.
This association matters early: elevated residual urine, high intravesical pressure, and vesicoureteral reflux can cause recurrent UTIs, hydronephrosis, and progressive renal injury. After surgical closure, evaluation includes renal ultrasonography, postvoid residual measurement, and urodynamic testing.
- A) Congenital heart malformation is not a characteristic association of myelomeningocele; the major associated structural CNS abnormality is Chiari II malformation with hydrocephalus.
- B) Cryptorchidism may occur independently but does not follow from disruption of the lumbosacral neural pathways.
- C) Folate deficiency or exposure to folate antagonists increases the risk of neural tube defects, but impaired folate metabolism is not the expected associated clinical finding in this newborn.
- E) Cognitive impairment can occur, particularly with hydrocephalus and its complications, but severe impairment is not implied by mild ventriculomegaly, a flat fontanel, and a normal head circumference.
Educational objective: When you see myelomeningocele with lower-extremity neurologic deficits, anticipate neurogenic bowel and bladder. Bladder dysfunction may be silent yet high-pressure, so renal imaging and urodynamic assessment are essential even without urinary dribbling.
Item 119 — Extrapolation of findings beyond data [Biostatistics & Prevention]
Answer: A — Extrapolation of findings beyond data
Reduced recurrence of ventricular tachycardia does not establish reduced mortality. The trial measured arrhythmia episodes—a surrogate endpoint—but the authors concluded benefit for an unmeasured patient-centered outcome, survival.
This distinction is crucial with antiarrhythmic drugs: suppression of ventricular arrhythmias may not improve survival and can even increase mortality through proarrhythmic effects. A mortality claim requires a trial designed and powered to compare deaths or an appropriately defined mortality endpoint, not merely recurrence frequency.
- B) Insufficient power would explain failure to detect a true difference. Here, recurrence differed significantly; the central flaw is that mortality was never evaluated.
- C) Confidence intervals are needed to assess effect size and precision, but their omission does not justify replacing the measured endpoint with mortality.
- D) Random allocation limits selection bias between treatment groups. No stem information suggests systematic differences in participant selection or allocation.
Educational objective: Remember: improvement in a surrogate endpoint cannot automatically be translated into improved survival. Conclusions must remain restricted to outcomes actually measured by the trial.
Item 120 — Subacute thyroiditis [Endocrine]
Answer: D — Subacute thyroiditis
Sore throat with a normal oropharynx plus tender anterior neck fullness is subacute thyroiditis. The pain is arising from the thyroid rather than the pharynx—a useful discriminator because de Quervain thyroiditis frequently mimics pharyngitis. Her age, sex, low-grade fever, and mild adrenergic features such as anxiety and tachycardia further support the diagnosis.
Inflammatory destruction of thyroid follicles releases preformed thyroid hormone, producing a transient thyrotoxic phase. Typical supporting tests would show elevated inflammatory markers, suppressed TSH with elevated thyroid hormones, and low radioactive iodine uptake because hormone is being released rather than newly synthesized.
- A) Acute mononucleosis usually causes exudative tonsillitis, posterior cervical lymphadenopathy, atypical lymphocytosis, and sometimes splenomegaly. Her normal oropharynx, absence of lymphadenopathy, and normal CBC argue against it.
- B) Gastroesophageal reflux disease may cause chronic throat irritation, globus, or hoarseness, but it does not produce a tender anterior neck swelling or fever.
- C) Laryngitis presents predominantly with hoarseness or voice loss, often following a viral upper respiratory infection. Neither voice change nor laryngeal symptoms are described.
- E) Tracheitis causes an acutely ill, febrile patient with cough, stridor, respiratory distress, or airway compromise—not localized thyroid tenderness with clear lungs.
Educational objective: When sore throat accompanies a normal pharyngeal examination, palpate the thyroid. A tender thyroid with low-grade fever and transient thyrotoxic features indicates subacute granulomatous thyroiditis.
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
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