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001A 62-year-old man has 50 minutes of crushing substernal pain, diaphoresis, and ST elevation in V2-V5. Which is the most likely diagnosis?Cardiovascular
A. Simple febrile seizure
B. Ovarian torsion
C. Physiologic neonatal jaundice
D. Hyperosmolar hyperglycemic state
E. Acute anterior STEMI
Correct answer: E. Acute anterior STEMI
Clinical reasoning: Acute anterior STEMI is the best diagnosis. Persistent ST-elevation myocardial infarction requires rapid reperfusion; biomarkers must not delay definitive therapy.
Exam pearl: Persistent ST-elevation myocardial infarction requires rapid reperfusion; biomarkers must not delay definitive therapy.
Clinical reasoning: Acute anterior STEMI is the best diagnosis. Persistent ST-elevation myocardial infarction requires rapid reperfusion; biomarkers must not delay definitive therapy.
Exam pearl: Persistent ST-elevation myocardial infarction requires rapid reperfusion; biomarkers must not delay definitive therapy.
051A 43-year-old woman 5 days after surgery develops sudden dyspnea, pleuritic pain, tachycardia, and hypoxemia. Which is the most likely diagnosis?Pulmonary
A. Polycystic ovary syndrome
B. Acute ischemic stroke
C. Convulsive status epilepticus
D. Severe falciparum malaria
E. Acute pulmonary embolism
Correct answer: E. Acute pulmonary embolism
Clinical reasoning: Acute pulmonary embolism is the best diagnosis. Diagnostic testing should follow pretest probability rather than indiscriminate D-dimer use.
Exam pearl: Diagnostic testing should follow pretest probability rather than indiscriminate D-dimer use.
Clinical reasoning: Acute pulmonary embolism is the best diagnosis. Diagnostic testing should follow pretest probability rather than indiscriminate D-dimer use.
Exam pearl: Diagnostic testing should follow pretest probability rather than indiscriminate D-dimer use.
101A 46-year-old has severe epigastric pain radiating to the back and lipase >3 times normal. Which is the most likely diagnosis?Gastrointestinal
A. Placenta previa
B. Simple febrile seizure
C. Nephrotic syndrome
D. Pneumocystis jirovecii pneumonia
E. Acute pancreatitis
Correct answer: E. Acute pancreatitis
Clinical reasoning: Acute pancreatitis is the best diagnosis. Diagnosis usually requires two of characteristic pain, enzyme elevation, or imaging findings.
Exam pearl: Diagnosis usually requires two of characteristic pain, enzyme elevation, or imaging findings.
Clinical reasoning: Acute pancreatitis is the best diagnosis. Diagnosis usually requires two of characteristic pain, enzyme elevation, or imaging findings.
Exam pearl: Diagnosis usually requires two of characteristic pain, enzyme elevation, or imaging findings.
151A cirrhotic patient becomes confused with asterixis after constipation and an upper GI bleed. Which is the most likely diagnosis?Hepatology
A. Wilson disease
B. Spontaneous bacterial peritonitis
C. Acute appendicitis
D. Viral croup
E. Hepatic encephalopathy
Correct answer: E. Hepatic encephalopathy
Clinical reasoning: Hepatic encephalopathy is the best diagnosis. Ammonia contributes to pathophysiology, but serum ammonia alone does not establish the diagnosis.
Exam pearl: Ammonia contributes to pathophysiology, but serum ammonia alone does not establish the diagnosis.
Clinical reasoning: Hepatic encephalopathy is the best diagnosis. Ammonia contributes to pathophysiology, but serum ammonia alone does not establish the diagnosis.
Exam pearl: Ammonia contributes to pathophysiology, but serum ammonia alone does not establish the diagnosis.
201A patient with several days of diarrhea has orthostasis, dry mucosa, and an acute rise in creatinine. Which is the most likely diagnosis?Renal
A. Heart failure with reduced ejection fraction
B. Sarcoidosis
C. Physiologic neonatal jaundice
D. Simple febrile seizure
E. Prerenal acute kidney injury
Correct answer: E. Prerenal acute kidney injury
Clinical reasoning: Prerenal acute kidney injury is the best diagnosis. Reduced renal perfusion increases sodium and water conservation when tubular function is intact.
Exam pearl: Reduced renal perfusion increases sodium and water conservation when tubular function is intact.
Clinical reasoning: Prerenal acute kidney injury is the best diagnosis. Reduced renal perfusion increases sodium and water conservation when tubular function is intact.
Exam pearl: Reduced renal perfusion increases sodium and water conservation when tubular function is intact.
251A 19-year-old with type 1 diabetes has abdominal pain, Kussmaul respirations, glucose 420 mg/dL, ketonemia, and anion-gap acidosis. Which is the most likely diagnosis?Endocrine
A. Non-ST-elevation acute coronary syndrome
B. Acute respiratory distress syndrome
C. Intussusception
D. Community-acquired pneumonia
E. Diabetic ketoacidosis
Correct answer: E. Diabetic ketoacidosis
Clinical reasoning: Diabetic ketoacidosis is the best diagnosis. Total-body potassium is depleted even when the initial serum potassium is normal or elevated.
Exam pearl: Total-body potassium is depleted even when the initial serum potassium is normal or elevated.
Clinical reasoning: Diabetic ketoacidosis is the best diagnosis. Total-body potassium is depleted even when the initial serum potassium is normal or elevated.
Exam pearl: Total-body potassium is depleted even when the initial serum potassium is normal or elevated.
301A 69-year-old develops aphasia and right hemiplegia 75 minutes ago; noncontrast CT shows no hemorrhage. Which is the most likely diagnosis?Neurology
A. Clostridioides difficile colitis
B. Hyperemesis gravidarum
C. Severe hypercalcemia of malignancy
D. Colorectal carcinoma until proven otherwise
E. Acute ischemic stroke
Correct answer: E. Acute ischemic stroke
Clinical reasoning: Acute ischemic stroke is the best diagnosis. Time last known well and large-vessel status determine reperfusion options.
Exam pearl: Time last known well and large-vessel status determine reperfusion options.
Clinical reasoning: Acute ischemic stroke is the best diagnosis. Time last known well and large-vessel status determine reperfusion options.
Exam pearl: Time last known well and large-vessel status determine reperfusion options.
351A woman at 7 weeks gestation has unilateral pelvic pain, spotting, positive hCG, and no intrauterine pregnancy on ultrasound. Which is the most likely diagnosis?Obstetrics
A. Idiopathic Parkinson disease
B. Wilson disease
C. Cardiac tamponade
D. Intussusception
E. Ectopic pregnancy
Correct answer: E. Ectopic pregnancy
Clinical reasoning: Ectopic pregnancy is the best diagnosis. Hemodynamic instability or rupture requires immediate operative management.
Exam pearl: Hemodynamic instability or rupture requires immediate operative management.
Clinical reasoning: Ectopic pregnancy is the best diagnosis. Hemodynamic instability or rupture requires immediate operative management.
Exam pearl: Hemodynamic instability or rupture requires immediate operative management.
401A 24-year-old has sudden severe unilateral pelvic pain, vomiting, and an enlarged ovary. Which is the most likely diagnosis?Gynecology
A. Acromegaly
B. Placenta previa
C. Eclampsia
D. Primary sclerosing cholangitis
E. Ovarian torsion
Correct answer: E. Ovarian torsion
Clinical reasoning: Ovarian torsion is the best diagnosis. High clinical suspicion warrants surgery despite imperfect imaging sensitivity.
Exam pearl: High clinical suspicion warrants surgery despite imperfect imaging sensitivity.
Clinical reasoning: Ovarian torsion is the best diagnosis. High clinical suspicion warrants surgery despite imperfect imaging sensitivity.
Exam pearl: High clinical suspicion warrants surgery despite imperfect imaging sensitivity.
426A 2-day-old term newborn develops jaundice but is feeding well; bilirubin is below treatment threshold and direct bilirubin is normal. Which is the most likely diagnosis?Pediatrics
A. Hepatorenal syndrome-AKI
B. Giant cell arteritis
C. Acute pancreatitis
D. Acromegaly
E. Physiologic neonatal jaundice
Correct answer: E. Physiologic neonatal jaundice
Clinical reasoning: Physiologic neonatal jaundice is the best diagnosis. Jaundice in the first 24 hours is pathologic until proven otherwise.
Exam pearl: Jaundice in the first 24 hours is pathologic until proven otherwise.
Clinical reasoning: Physiologic neonatal jaundice is the best diagnosis. Jaundice in the first 24 hours is pathologic until proven otherwise.
Exam pearl: Jaundice in the first 24 hours is pathologic until proven otherwise.
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