Examkin

All practice questions

1849 questions

All types8,270Multiple choice4,249Multiple select325Numeric160Matching1,849Ordering1,687
Question 1681Question →

Determine the most appropriate immediate surgical or procedural intervention for each of the following critically injured trauma patients.

Click a left item, then click its matching right item

Items

A 27-year-old man with a parasternal stab wound, profound hypotension, jugular venous distention, and a FAST exam showing pericardial effusion.
A 39-year-old woman with a crushed pelvis, persistent hemodynamic instability despite blood transfusion and binder placement, and a negative FAST exam.
A 42-year-old man with blunt abdominal trauma, transient hemodynamic response to fluid resuscitation, and a FAST exam showing fluid in the hepatorenal recess.
A 31-year-old man with a zone II anterior neck stab wound, rapidly expanding hematoma, severe stridor, and failed attempts at orotracheal intubation.
A 22-year-old man with a gunshot wound to the distal thigh, an expanding pulsatile hematoma, absent pedal pulses, and a cold, pale foot.

Matches

Show answer & explanation

Answer

The correct pairings identify the immediate life-saving intervention for each specific traumatic presentation based on ATLS protocols: cardiac tamponade requires thoracotomy, retroperitoneal pelvic bleeding requires angiography or packing, unstable intraperitoneal bleeding requires laparotomy, a 'cannot intubate, cannot oxygenate' airway requires cricothyroidotomy, and hard signs of vascular injury require operative exploration.
Each clinical scenario presents a classic ATLS decision point. The neck stab wound patient has an impending airway disaster with failed intubation, necessitating a surgical cricothyroidotomy. The patient with the parasternal stab wound has cardiac tamponade and requires a thoracotomy. The blunt abdominal trauma patient is unstable with a positive FAST, mandating an exploratory laparotomy. The pelvic fracture patient is unstable with a negative FAST, meaning the bleeding is retroperitoneal and requires angioembolization or packing. Finally, the extremity trauma patient has hard signs of vascular injury, requiring immediate operative vascular exploration.

Step-by-Step Solution

1
Evaluate the airway and breathing status.
The patient with the neck stab wound and failed intubation has a definitively compromised airway.
Airway is the first priority in the ATLS primary survey, and a definitive surgical airway must be established when non-surgical methods fail.
2
Assess circulation and identify the anatomical source of shock.
Shock sources are localized to the pericardium (tamponade), retroperitoneum (pelvis), and intraperitoneal space (abdomen).
Interventions for shock are location-specific; misidentifying the bleeding source leads to incorrect and potentially fatal surgical approaches.
3
Match specific hard signs of vascular trauma to operative management.
The extremity gunshot wound exhibits hard signs (pulsatile hematoma, absent pulses).
Hard signs of vascular injury mandate immediate surgical exploration rather than further diagnostic imaging.

Key Concept

Advanced Trauma Life Support (ATLS) Primary Survey and Resuscitation Algorithms
Question 1682Question →

Match each patient's clinical presentation with the most appropriate definitive management or next step in intervention.

Click a left item, then click its matching right item

Items

An 82-year-old intubated ICU patient develops fever and leukocytosis; abdominal ultrasound reveals a thickened gallbladder wall, pericholecystic fluid, and no gallstones.
A 74-year-old female presents with obstipation, bilious vomiting, and imaging demonstrating pneumobilia alongside dilated loops of small bowel.
A 66-year-old male presents with right upper quadrant pain, jaundice, fever, confusion, and a blood pressure of 82/50 mm Hg.
A 42-year-old female reports episodic, crampy right upper quadrant pain following fatty meals; ultrasound shows echogenic foci with acoustic shadowing and a normal gallbladder wall.

Matches

Show answer & explanation

Answer

The correct pairings align the specific hepatobiliary or gastrointestinal pathology with its guideline-directed intervention based on severity and anatomy.
Each presentation represents a distinct pathology with a specific algorithmic treatment approach based on the severity of illness. Critically ill patients with acalculous cholecystitis need percutaneous drainage. Gallstone ileus requires surgical removal of the obstructing stone. Reynolds pentad indicates severe ascending cholangitis requiring emergent ERCP decompression. Uncomplicated biliary colic is treated electively.

Step-by-Step Solution

1
Analyze each clinical vignette to establish the most likely diagnosis.
Identified acalculous cholecystitis, gallstone ileus, acute suppurative cholangitis, and biliary colic.
Accurate diagnosis is the prerequisite for selecting the correct surgical or procedural management.
2
Determine the hemodynamic status and surgical risk of each patient.
The ICU patient and the patient with Reynolds pentad are highly unstable, requiring minimally invasive or emergent temporizing procedures rather than immediate major surgery.
Surgical risk stratification determines whether a definitive operation or a temporizing drainage procedure is appropriate.
3
Match the diagnosis and stability to the intervention.
Matched acalculous cholecystitis to percutaneous drainage, gallstone ileus to enterolithotomy, severe cholangitis to ERCP, and biliary colic to elective surgery.
This aligns with standard gastrointestinal and abdominal surgery treatment algorithms.

Key Concept

Surgical Triage and Management of Biliary and Gastrointestinal Pathologies
Question 1683Question →

Review the following diagnostic laboratory profiles of patients presenting with cushingoid features (such as central obesity, proximal muscle weakness, and abdominal striae). Match each laboratory and testing profile with its most appropriate underlying pathophysiologic etiology.

Click a left item, then click its matching right item

Items

Elevated 24-hour urine free cortisol; suppressed plasma ACTH level
Elevated 24-hour urine free cortisol; elevated plasma ACTH level; serum cortisol suppresses by >50% following a high-dose dexamethasone test
Elevated 24-hour urine free cortisol; elevated plasma ACTH level; no significant suppression of serum cortisol following a high-dose dexamethasone test
Low 24-hour urine free cortisol; suppressed plasma ACTH level; low morning serum cortisol level

Matches

Show answer & explanation

Answer

Profile 1 matches Adrenal adenoma. Profile 2 matches Pituitary adenoma. Profile 3 matches Ectopic ACTH secretion. Profile 4 matches Exogenous glucocorticoid use.
The standard diagnostic approach to Cushing syndrome requires step-wise biochemical evaluation. Once hypercortisolism is confirmed (via 24-hour urine free cortisol, late-night salivary cortisol, or low-dose dexamethasone suppression), plasma ACTH is measured. Suppressed ACTH (<5 pg/mL) indicates ACTH-independent disease (e.g., adrenal adenoma). If a patient has suppressed ACTH, low urine cortisol, and cushingoid features, it is diagnostic of exogenous corticosteroid use. Conversely, an elevated ACTH level indicates an ACTH-dependent state. High-dose dexamethasone (8 mg) is then utilized: pituitary adenomas will suppress their ACTH secretion (decreasing cortisol by >50%), whereas ectopic ACTH-producing tumors will not suppress.

Step-by-Step Solution

1
Evaluate the plasma ACTH level in the context of cushingoid features.
A suppressed ACTH level indicates an ACTH-independent process (adrenal or exogenous). An elevated or inappropriately normal ACTH level indicates an ACTH-dependent process (pituitary or ectopic).
Cortisol normally exerts negative feedback on the pituitary. If cortisol is high and ACTH is suppressed, the source of cortisol is outside the pituitary axis.
2
Differentiate the ACTH-independent causes based on cortisol levels.
High endogenous cortisol with low ACTH points to an adrenal adenoma or carcinoma. Low endogenous cortisol with low ACTH in a patient with cushingoid signs strongly points to exogenous synthetic glucocorticoid use.
Synthetic glucocorticoids (like prednisone or dexamethasone) cause tissue manifestations of Cushing syndrome and suppress the HPA axis but are not cross-reactive on standard serum/urine cortisol assays, leading to low measured levels.
3
Differentiate the ACTH-dependent causes using the high-dose dexamethasone suppression test.
Suppression of serum cortisol indicates a pituitary adenoma (Cushing disease). Lack of suppression indicates an ectopic ACTH source (e.g., small cell lung cancer).
Pituitary corticotroph adenomas retain partial sensitivity to glucocorticoid negative feedback, whereas ectopic neuroendocrine tumors typically lack functional glucocorticoid receptors and secrete ACTH entirely autonomously.

Key Concept

The diagnostic algorithm for Cushing syndrome (hypercortisolism) utilizes ACTH levels to determine dependency, followed by high-dose dexamethasone suppression to localize the source of ACTH.
Question 1684Question →

Match each clinical presentation of shock with its most characteristic invasive hemodynamic profile (Central Venous Pressure [CVP], Pulmonary Capillary Wedge Pressure [PCWP], Cardiac Index [CI], and Systemic Vascular Resistance [SVR]).

Click a left item, then click its matching right item

Items

24-year-old man with massive abdominal hemorrhage after a motor vehicle collision
68-year-old woman with an extensive anterior ST-elevation myocardial infarction
72-year-old man with warm extremities, fever, and Escherichia coli bacteremia
45-year-old woman with an acute massive pulmonary embolism and severe dyspnea

Matches

Show answer & explanation

Answer

Massive abdominal hemorrhage matches the hypovolemic profile (Decreased CVP/PCWP, Decreased CI, Increased SVR). Anterior myocardial infarction matches the cardiogenic profile (Increased CVP/PCWP, Decreased CI, Increased SVR). E. coli bacteremia matches the distributive profile (Decreased/Normal CVP/PCWP, Increased CI, Decreased SVR). Massive pulmonary embolism matches the obstructive profile (Increased CVP, Decreased/Normal PCWP, Decreased CI, Increased SVR).
Each physiological classification of shock presents with a unique pattern of hemodynamic variables that dictates its management.

Shock TypeCVP (Right Preload)PCWP (Left Preload)Cardiac Index (Pump)SVR (Afterload)
HypovolemicDecreasedDecreasedDecreasedIncreased
CardiogenicIncreasedIncreasedDecreasedIncreased
Distributive (Septic)Decreased/NormalDecreased/NormalIncreasedDecreased
Obstructive (PE)IncreasedDecreased/NormalDecreasedIncreased
Hypovolemic shock involves a global volume deficit. Cardiogenic shock involves a failing pump leading to vascular congestion. Septic shock fundamentally involves a loss of vascular tone (low SVR) leading to a hyperdynamic heart. Obstructive shock (specifically PE) represents a barrier between the right and left heart, causing congestion before the block and underfilling after it.

Step-by-Step Solution

1
Evaluate the underlying mechanism for the massive abdominal hemorrhage scenario.
Identified as hypovolemic shock.
Significant blood loss directly reduces venous return (preload) to both sides of the heart.
2
Evaluate the underlying mechanism for the anterior myocardial infarction scenario.
Identified as cardiogenic shock.
Anterior ischemia causes primary left ventricular systolic dysfunction and forward flow failure.
3
Evaluate the underlying mechanism for the E. coli bacteremia scenario.
Identified as septic (distributive) shock.
Endotoxins cause massive peripheral vasodilation, which is the hallmark primary derangement in this shock state.
4
Evaluate the underlying mechanism for the massive pulmonary embolism scenario.
Identified as obstructive shock.
A physical blockage in the pulmonary arteries impedes flow from the right side of the heart to the left.
5
Map the derived mechanisms to their respective hemodynamic patterns.
Matched each scenario to the right-side item containing the correct physiological derangements.
Hemodynamic parameters logically follow the primary mechanism: pump failure increases preload parameters behind the failure, volume loss decreases all preload parameters, vasodilation decreases afterload, and right-sided obstruction increases right-sided preload while starving the left side.

Key Concept

Hemodynamic profiles of shock states (hypovolemic, cardiogenic, distributive, and obstructive).
Question 1685Question →

Match the following diagnostic laboratory profiles of calcium and phosphate homeostasis to their most likely underlying pathophysiologic etiology. Assume all patients have normal serum albumin and normal magnesium levels unless otherwise indicated.

Click a left item, then click its matching right item

Items

Ca2+↑\text{Ca}^{2+} \uparrow, PO43−↓\text{PO}_4^{3-} \downarrow, PTH↑\text{PTH} \uparrow, 24-hr urine Ca2+↑\text{24-hr urine Ca}^{2+} \uparrow
Ca2+↑\text{Ca}^{2+} \uparrow, PO43−↔\text{PO}_4^{3-} \leftrightarrow, PTH↔or↑\text{PTH} \leftrightarrow \text{or} \uparrow, urine calcium-to-creatinine clearance ratio<0.01\text{urine calcium-to-creatinine clearance ratio} < 0.01
Ca2+↓\text{Ca}^{2+} \downarrow, PO43−↓\text{PO}_4^{3-} \downarrow, PTH↑\text{PTH} \uparrow, 25(OH)D↓\text{25(OH)D} \downarrow, 1,25(OH)2D↓\text{1,25(OH)}_2\text{D} \downarrow
Ca2+↓\text{Ca}^{2+} \downarrow, PO43−↑\text{PO}_4^{3-} \uparrow, PTH↑\text{PTH} \uparrow, 1,25(OH)2D↓\text{1,25(OH)}_2\text{D} \downarrow, BUN/Cr↑\text{BUN}/\text{Cr} \uparrow
Ca2+↑\text{Ca}^{2+} \uparrow, PO43−↔or↑\text{PO}_4^{3-} \leftrightarrow \text{or} \uparrow, PTH↓\text{PTH} \downarrow, 1,25(OH)2D↑\text{1,25(OH)}_2\text{D} \uparrow, 25(OH)D↔\text{25(OH)D} \leftrightarrow

Matches

Show answer & explanation

Answer

1 matches Primary hyperparathyroidism, 2 matches Familial hypocalciuric hypercalcemia, 3 matches Severe dietary vitamin D deficiency, 4 matches End-stage renal disease, 5 matches Granulomatous disease.
Accurate diagnosis of calcium disorders requires interpreting the directionality of PTH relative to calcium, assessing renal handling of these electrolytes, and recognizing the different active forms of vitamin D. Identifying the etiology dictates appropriate management (e.g., surgery for primary hyperparathyroidism vs. observation for FHH).

Step-by-Step Solution

1
Analyze the serum calcium and PTH levels as the primary diagnostic branch point.
Hypercalcemia with high/normal PTH indicates PTH-dependent hypercalcemia (profiles 1 and 2). Hypercalcemia with low PTH indicates PTH-independent hypercalcemia (profile 5). Hypocalcemia with high PTH indicates secondary hyperparathyroidism (profiles 3 and 4).
PTH is the primary regulator of serum calcium; its response defines the core pathophysiologic category.
2
Evaluate urine calcium excretion in patients with PTH-dependent hypercalcemia.
Profile 1 shows high urine calcium (Primary hyperparathyroidism), whereas Profile 2 shows a calcium-to-creatinine clearance ratio < 0.01 (Familial hypocalciuric hypercalcemia).
FHH mimics mild primary hyperparathyroidism but is distinguished by profound renal calcium conservation due to CaSR mutation.
3
Examine renal function, phosphorus, and vitamin D levels in hypocalcemic patients.
Profile 4 has elevated BUN/Cr and hyperphosphatemia (End-stage renal disease). Profile 3 has normal renal function, hypophosphatemia, and low 25(OH)D (Dietary vitamin D deficiency).
Kidneys excrete phosphate; renal failure causes phosphate retention, whereas pure vitamin D deficiency decreases intestinal phosphate absorption and triggers phosphaturic secondary hyperparathyroidism.
4
Investigate the mechanism of PTH-independent hypercalcemia in Profile 5.
Suppressed PTH with elevated 1,25(OH)2D but normal 25(OH)D points to extrarenal 1-alpha-hydroxylase activity.
Granulomatous diseases like sarcoidosis produce active vitamin D independently of PTH regulation, causing hypercalcemia and suppressing endogenous PTH.

Key Concept

Differential diagnosis of calcium and phosphate disorders
Question 1686Question →

Match each detailed clinical description of a cardiac murmur and its response to dynamic physiological maneuvers with the correct underlying structural pathology.

Click a left item, then click its matching right item

Items

Harsh crescendo-decrescendo systolic murmur at the second right intercostal space; intensity decreases during the strain phase of the Valsalva maneuver and increases with passive leg raise.
Harsh systolic murmur at the left lower sternal border; intensity increases during the strain phase of the Valsalva maneuver and decreases with passive leg raise.
Blowing holosystolic murmur at the apex; intensity increases with isometric handgrip and decreases with the inhalation of amyl nitrite.
High-pitched, early diastolic decrescendo murmur at the left third intercostal space; intensity increases with isometric handgrip and decreases during the strain phase of the Valsalva maneuver.
Late systolic murmur preceded by a mid-systolic click at the apex; the click occurs earlier in systole and the murmur duration lengthens during the strain phase of the Valsalva maneuver.

Matches

Show answer & explanation

Answer

The pairings are as follows: Aortic valve stenosis matches the systolic murmur that softens with Valsalva. Hypertrophic obstructive cardiomyopathy matches the systolic murmur that gets louder with Valsalva. Mitral regurgitation matches the holosystolic murmur that increases with handgrip. Aortic regurgitation matches the diastolic murmur that increases with handgrip. Mitral valve prolapse matches the murmur where the click occurs earlier with Valsalva.
The correct pairings rely on the physiological principles of preload and afterload on valvular pressure gradients. Increased preload (passive leg raise, squatting) generally increases the intensity of flow murmurs (Aortic Stenosis, Aortic Regurgitation, Mitral Regurgitation) but decreases the murmur of Hypertrophic Obstructive Cardiomyopathy and delays the click of Mitral Valve Prolapse. Increased afterload (handgrip) increases the intensity of regurgitant murmurs (Mitral Regurgitation, Aortic Regurgitation) by forcing more blood backward, while decreasing the murmur of Aortic Stenosis and Hypertrophic Obstructive Cardiomyopathy. The Valsalva strain phase profoundly decreases preload, thereby accentuating Hypertrophic Obstructive Cardiomyopathy and moving the Mitral Valve Prolapse click earlier in systole, while softening most other murmurs.

Step-by-Step Solution

1
Analyze the baseline timing, quality, and location of each murmur.
Categorizes the murmurs into specific valve origins (e.g., systolic at the apex suggests mitral origin; diastolic at the left sternal border suggests aortic regurgitation).
Baseline auscultatory characteristics narrow the differential diagnosis before considering complex dynamic changes.
2
Evaluate the response to maneuvers that change preload (Valsalva strain phase, passive leg raise).
Differentiates flow-dependent murmurs from volume-inversely-dependent murmurs. Most murmurs soften with decreased preload (Valsalva), except Hypertrophic Obstructive Cardiomyopathy (becomes louder) and Mitral Valve Prolapse (becomes longer and occurs earlier).
Preload maneuvers definitively isolate Hypertrophic Obstructive Cardiomyopathy and Mitral Valve Prolapse from other systolic murmurs.
3
Evaluate the response to maneuvers that change afterload (isometric handgrip, amyl nitrite).
Identifies regurgitant lesions versus forward-flow lesions. Handgrip increases afterload, making regurgitant murmurs (Aortic Regurgitation, Mitral Regurgitation) louder. Amyl nitrite decreases afterload, making regurgitant murmurs softer.
Afterload maneuvers are critical to confirm the mechanical nature of regurgitant lesions, which worsen when systemic resistance increases.

Key Concept

Dynamic auscultation uses physiological maneuvers to alter cardiac hemodynamics (preload and afterload), allowing for the clinical differentiation of structurally similar murmurs.
Estimated Time:2m 0s
Question 1687Question →

Match each classic peripheral arterial pulse abnormality with its most commonly associated cardiovascular pathology.

Click a left item, then click its matching right item

Items

Pulsus paradoxus (>10 mm Hg drop in systolic blood pressure during inspiration)
Pulsus parvus et tardus (Weak and delayed pulse upstroke)
Water-hammer pulse (Bounding, rapidly rising and collapsing pulse)
Pulsus alternans (Alternating amplitude of pulse waves despite a regular rhythm)

Matches

Show answer & explanation

Answer

Pulsus paradoxus matches Cardiac tamponade; Pulsus parvus et tardus matches Severe aortic stenosis; Water-hammer pulse matches Severe aortic regurgitation; Pulsus alternans matches Advanced left ventricular systolic dysfunction.
Each peripheral pulse abnormality has a specific hemodynamic mechanism linking it to a primary cardiac condition, such as fixed outflow obstruction causing parvus et tardus, or ventricular interdependence causing pulsus paradoxus.

Step-by-Step Solution

1
Analyze the definition of pulsus paradoxus.
It describes an exaggerated drop in systolic blood pressure with inspiration.
Recognizing the physiological basis points to conditions with impaired right ventricular expansion, which pushes the septum into the left ventricle, classic for cardiac tamponade.
2
Analyze pulsus parvus et tardus.
It describes a weak and delayed pulse.
This is caused by a fixed mechanical obstruction to left ventricular outflow, characteristic of severe aortic stenosis.
3
Analyze water-hammer pulse.
It is a bounding pulse with rapid rise and fall.
This results from a widened pulse pressure and rapid runoff of blood back into the left ventricle, pathognomonic for severe aortic regurgitation.
4
Analyze pulsus alternans.
It features alternating strong and weak beats.
This indicates alternating left ventricular contractile force, which is a hallmark of severe left ventricular systolic failure.

Key Concept

Specific peripheral pulse abnormalities provide critical diagnostic clues that directly correlate with distinct structural and functional cardiac pathologies.
Question 1688Question →

Match each clinical presentation of a gastrointestinal or hepatobiliary disorder to its most appropriate evidence-based next step in management.

Click a left item, then click its matching right item

Items

A 58-year-old female with known decompensated cirrhosis is evaluated for new-onset lethargy and generalized abdominal discomfort; paracentesis yields fluid with a neutrophil count of 620/mm³.
A 65-year-old male is evaluated in the outpatient setting for mild left lower quadrant tenderness; a recent computed tomography scan confirms acute diverticulitis with no evidence of complications, and his vital signs remain normal.
A 71-year-old female with a long-standing history of systemic sclerosis reports months of loose stools and unintentional weight loss; laboratory evaluation reveals macrocytic anemia and a positive carbohydrate breath test.
A 44-year-old male develops profuse, foul-smelling diarrhea and a white blood cell count of 16,000/µL one week into a course of parenteral ceftriaxone for lobar pneumonia; stool testing is positive.

Matches

Show answer & explanation

Answer

The cirrhotic patient with SBP requires IV cephalosporins and albumin. The patient with uncomplicated diverticulitis should receive conservative management without routine antibiotics. The scleroderma patient with SIBO requires oral rifaximin. The patient with C. difficile colitis should be treated with oral fidaxomicin.
Each clinical presentation is matched to its guideline-directed therapy: SBP requires IV antibiotics and albumin to lower mortality; uncomplicated diverticulitis is managed conservatively without antibiotics to promote stewardship; SIBO requires targeted intraluminal eradication with rifaximin; and severe C. difficile requires oral fidaxomicin.

Step-by-Step Solution

1
Evaluate the clinical vignette of the 58-year-old female with cirrhosis and an ascitic fluid neutrophil count >250/mm³.
Diagnose Spontaneous Bacterial Peritonitis (SBP).
An ascitic neutrophil count of 250/mm³ or greater is the diagnostic threshold for SBP, necessitating immediate treatment to prevent severe complications.
2
Determine the optimal therapy for SBP.
Match with intravenous third-generation cephalosporins and albumin.
IV antibiotics cover typical enteric pathogens, while IV albumin significantly reduces the incidence of renal impairment (hepatorenal syndrome) and improves mortality.
3
Evaluate the 65-year-old male with CT-confirmed acute, uncomplicated diverticulitis and normal vital signs.
Determine that he is a candidate for conservative outpatient management.
He is hemodynamically stable, immunocompetent, and lacks systemic signs of severe infection or CT evidence of complications.
4
Select the appropriate management approach for mild diverticulitis.
Match with conservative management and strict avoidance of routine antimicrobial therapy.
Evidence-based guidelines emphasize antibiotic stewardship, showing no benefit to routine antibiotics in uncomplicated diverticulitis.
5
Evaluate the 71-year-old female with systemic sclerosis, macrocytic anemia, and a positive carbohydrate breath test.
Diagnose Small Intestinal Bacterial Overgrowth (SIBO).
Dysmotility from systemic sclerosis allows colonic bacteria to proliferate in the small bowel, causing malabsorption and a positive breath test.
6
Determine the targeted treatment for SIBO.
Match with oral rifaximin.
Rifaximin is a non-absorbable antibiotic that targets intraluminal bacteria in the gut without causing significant systemic effects.
7
Evaluate the 44-year-old male with profuse diarrhea and leukocytosis following ceftriaxone therapy.
Identify severe Clostridioides difficile infection.
Recent antibiotic use followed by significant diarrhea and an elevated WBC count >15,000/µL are hallmarks of a severe C. difficile infection.
8
Select the first-line management for severe C. difficile.
Match with halting the current antibiotic and initiating oral fidaxomicin.
Fidaxomicin is a preferred first-line agent due to its narrow spectrum and lower recurrence rates compared to oral vancomycin.

Key Concept

Appropriate selection of antimicrobial therapies and implementation of antibiotic stewardship principles in gastrointestinal and hepatobiliary disorders.
Question 1689Question →

Match each clinical presentation of a gastrointestinal or hepatic condition with the most appropriate next step in antimicrobial management, demonstrating evidence-based principles of antibiotic stewardship.

Click a left item, then click its matching right item

Items

A 6565-year-old man with Child-Pugh class C cirrhosis is admitted to the intensive care unit with an acute esophageal variceal hemorrhage. He is hemodynamically stabilized following urgent endoscopic band ligation. He does not have ascites, and initial blood cultures show no growth at 2424 hours.
A 5050-year-old man with a 66 cm amebic liver abscess, confirmed by positive Entamoeba histolytica serology, completes a 1010-day course of oral metronidazole. His fever and right upper quadrant pain have completely resolved, but a follow-up ultrasound reveals the abscess cavity is unchanged in size.
A 7272-year-old woman with acute cholangitis secondary to choledocholithiasis undergoes emergent endoscopic retrograde cholangiopancreatography (ERCP) with successful stone extraction and biliary sphincterotomy. She received intravenous piperacillin-tazobactam prior to the procedure. She is now afebrile, and her bilirubin levels are rapidly trending downward.
A 4545-year-old man with severe acute gallstone pancreatitis develops >30%>30\% pancreatic glandular necrosis on a contrast-enhanced computed tomography scan obtained on hospital day 55. He remains hemodynamically stable and afebrile, with a leukocyte count of 12,000/μL12,000/\mu L.

Matches

Show answer & explanation

Answer

The correct pairings align each clinical scenario with precise antimicrobial stewardship guidelines: variceal bleeding requires mandatory 77-day prophylaxis; resolved amebic abscesses require luminal cyst eradication; post-ERCP cholangitis requires rapid antibiotic cessation; and sterile pancreatic necrosis requires the withholding of empirical antibiotics.
Each clinical scenario tests a high-yield principle of antimicrobial stewardship within gastroenterology. Variceal bleeding universally requires short-term prophylaxis. Amebic abscesses require a luminal agent for cyst eradication, not prolonged tissue antibiotics. Post-ERCP cholangitis requires prompt antibiotic cessation after source control. Sterile pancreatic necrosis strictly requires avoiding prophylactic antibiotics.

Step-by-Step Solution

1
Analyze the variceal bleeding scenario (Cirrhosis without ascites).
Matches with completing a 77-day course of intravenous ceftriaxone or an oral fluoroquinolone.
Gastrointestinal bleeding in cirrhosis causes bacterial translocation. Short-term prophylactic antibiotics are universally indicated to prevent infections and improve survival, even if ascites is absent and cultures are currently negative.
2
Analyze the amebic liver abscess scenario (Clinically resolved, radiographically unchanged).
Matches with initiating a course of oral paromomycin or intraluminal diloxanide furoate.
Metronidazole treats the invasive tissue infection, but it poorly penetrates the bowel lumen where Entamoeba cysts reside. Paromomycin is required to eradicate the carrier state. The static abscess size is expected and does not justify further tissue-directed antibiotics.
3
Analyze the acute cholangitis scenario (Successful ERCP source control).
Matches with discontinuing intravenous antibiotics within 2424 to 7272 hours.
The primary treatment for cholangitis is biliary decompression. Once the obstruction is cleared and the patient demonstrates clinical improvement, continuing broad-spectrum antibiotics (like piperacillin-tazobactam) for a traditional 77- to 1414-day course is inappropriate and violates stewardship principles.
4
Analyze the severe acute pancreatitis scenario (Sterile necrosis).
Matches with providing supportive care without initiating empirical antimicrobial therapy.
The patient is afebrile and stable, indicating sterile necrosis. Routine antibiotic prophylaxis (e.g., with carbapenems) to prevent infection of the necrotic tissue is strongly recommended against by current guidelines.

Key Concept

Evidence-based antimicrobial stewardship in gastroenterology and hepatology emphasizes source control over prolonged antibiotic durations, targeted eradication of specific pathogen life cycles, and the avoidance of empirical prophylaxis in sterile inflammatory conditions.
Question 1690Question →

Match each patient's clinical presentation with the most likely underlying postoperative or gastrointestinal complication.

Click a left item, then click its matching right item

Items

A 62-year-old male on post-operative day 3 following an elective sigmoid resection. He has nausea, no passage of flatus, and generalized tympany. Abdominal radiography reveals dilated loops of both small and large bowel without a discrete transition zone.
A 78-year-old male recovering in the intensive care unit on day 4 following a coronary artery bypass graft. He develops massive, painless abdominal distension. Radiography reveals a cecal diameter of 11 cm with a normal-caliber small bowel and no mechanical obstruction.
A 55-year-old female on post-operative day 6 after a left hemicolectomy. She suddenly develops severe, diffuse abdominal pain, a temperature of 39.2°C (102.5°F), tachycardia, and board-like abdominal rigidity.
A 45-year-old male presenting to the emergency department 8 months after an exploratory laparotomy for trauma. He reports severe, intermittent, cramping abdominal pain and bilious vomiting. Examination reveals hyperactive, high-pitched bowel sounds.

Matches

Show answer & explanation

Answer

The patient with diffuse bowel dilation without a transition point has postoperative ileus; the ICU patient with isolated massive cecal dilation has acute colonic pseudo-obstruction (Ogilvie syndrome); the post-colectomy patient with sudden peritonitis has an anastomotic leak; and the patient with prior laparotomy and colicky pain has an adhesive small bowel obstruction.
Each presentation highlights a distinct gastrointestinal complication. Postoperative ileus involves diffuse functional dysmotility. Ogilvie syndrome features isolated massive colonic dilation in critically ill patients. Anastomotic leak presents with acute peritonitis and sepsis days after bowel anastomosis. Adhesive small bowel obstruction presents with mechanical blockage symptoms months to years after laparotomy.

Step-by-Step Solution

1
Analyze the patient's surgical history and the timing of symptom onset.
Identified whether the presentation is acute (days post-op) or delayed (months to years later).
Complications like anastomotic leaks and ileus occur within days of surgery, whereas adhesive obstructions typically present months to years later.
2
Evaluate the physical exam findings.
Differentiated between functional dysmotility (absent or hypoactive bowel sounds), mechanical blockage (hyperactive or high-pitched sounds), and peritonitis (rigidity, fever).
Physical exam findings narrow down the differential between inflammatory/infectious causes and obstructive causes.
3
Correlate with abdominal imaging results.
Confirmed the specific pattern of bowel dilation.
Diffuse dilation implies ileus, isolated marked colonic dilation implies Ogilvie syndrome, and a discrete transition zone implies a mechanical obstruction.

Key Concept

Differentiating common postoperative and mechanical gastrointestinal complications based on clinical presentation, timing, and radiographic findings.
Question 1691Question →

A thorough urinalysis is a critical non-invasive tool for localizing the site of renal injury in patients with acute or chronic kidney disease. For each characteristic urinalysis sediment finding presented below, what is the most likely associated renal pathology? Match each finding to its correct etiology.

Click a left item, then click its matching right item

Items

Muddy brown granular casts
Red blood cell (RBC) casts
White blood cell (WBC) casts
Fatty casts and oval fat bodies
Broad waxy casts

Matches

Show answer & explanation

Answer

Muddy brown casts indicate acute tubular necrosis; RBC casts indicate proliferative glomerulonephritis; WBC casts indicate acute interstitial nephritis; fatty casts indicate nephrotic syndrome; and broad waxy casts indicate advanced chronic kidney disease.
Urinary casts serve as specific markers that localize the source of renal pathology. Glomerular injury allows RBCs to pass and form RBC casts; tubular necrosis causes epithelial sloughing to form muddy brown casts; interstitial inflammation leads to WBC casts; severe proteinuria enables lipiduria to form fatty casts; and chronic structural dilation from nephron loss produces broad waxy casts.

Step-by-Step Solution

1
Determine the significance of cellular versus acellular casts.
Cellular casts indicate active inflammation or necrosis within the nephron, whereas acellular or degenerative casts often indicate stasis or severe proteinuria.
Casts are formed in the distal nephron when Tamm-Horsfall mucoprotein traps available luminal contents, reflecting the specific pathology occurring upstream.
2
Evaluate the clinical implication of muddy brown granular casts.
They are linked to acute tubular necrosis.
Ischemic or nephrotoxic injury causes tubular cells to die, slough off, and degrade into muddy brown granular material.
3
Evaluate the implication of specific immune cells (RBCs and WBCs) in casts.
RBC casts point to glomerular disease (nephritic syndrome), while WBC casts point to tubulointerstitial disease (AIN or pyelonephritis).
The type of cell trapped in the cast reflects the primary site of structural damage and inflammation.
4
Evaluate the implication of fatty and broad waxy casts.
Fatty casts suggest nephrotic syndrome, and broad waxy casts suggest advanced chronic kidney disease.
Lipiduria accompanies the severe proteinuria seen in nephrotic syndrome. Waxy casts result from extreme stasis in enlarged tubules of failing kidneys over a long period.

Key Concept

Urinalysis Cast Interpretation in Renal Pathologies
Estimated Time:1m 0s
Question 1692Question →

Review the following descriptions of patients presenting to the emergency department following various traumatic events. Pair each specific clinical scenario with its unequivocally correct next step in diagnostic evaluation or acute management.

Click a left item, then click its matching right item

Items

A 30-year-old man sustains a stab wound to the left eighth intercostal space at the midaxillary line. He is hemodynamically stable. Focused assessment with sonography for trauma (FAST) and chest radiograph are normal.
A 45-year-old woman is involved in a high-speed frontal motor vehicle collision. She is normotensive. Initial chest radiograph demonstrates a widened mediastinum and blurring of the aortic knob.
A 25-year-old man suffers a gunshot wound to the right hemithorax. He is tachycardic and hypotensive. Tube thoracostomy is performed, resulting in an immediate evacuation of 1,600 mL of bright red blood.
A 60-year-old man presents after a severe fall. He exhibits paradoxical inward movement of a right anterior chest wall segment during inspiration and remains persistently hypoxemic despite high-flow oxygen therapy.

Matches

Show answer & explanation

Answer

The scenarios pair as follows: left thoracoabdominal stab wound matches with diagnostic laparoscopy; widened mediastinum matches with CT angiography; massive hemothorax matches with emergent operative thoracotomy; flail chest with respiratory failure matches with endotracheal intubation.
Each clinical presentation tests a distinct node in the Advanced Trauma Life Support (ATLS) algorithm. Hemodynamically stable patients with specific occult injury risks (like blunt aortic injury or diaphragmatic penetration) require targeted evaluation with CT angiography or diagnostic laparoscopy, respectively. In contrast, life-threatening derangements like massive hemothorax (>1,500 mL blood) or flail chest with respiratory failure demand immediate, definitive intervention such as emergent thoracotomy or intubation with positive pressure ventilation.

Step-by-Step Solution

1
Analyze the stab wound scenario.
Stable patient with a left-sided wound in the 'thoracoabdominal box' (T4-T12). FAST and CXR are negative.
Occult diaphragmatic injuries are easily missed by initial imaging. Laparoscopy is required to prevent delayed diaphragmatic hernia.
2
Analyze the high-speed collision scenario.
Stable patient with a widened mediastinum.
Suspicion for blunt aortic injury is high. A stable patient can safely undergo CT angiography for definitive diagnosis.
3
Analyze the gunshot wound scenario.
Unstable patient with 1,600 mL of immediate blood output from a chest tube.
This meets criteria for a massive hemothorax (> 1,500 mL initial, or > 200 mL/hr for 2-4 hours), requiring immediate surgical control via thoracotomy.
4
Analyze the fall scenario.
Patient with paradoxical chest wall movement and refractory hypoxemia.
Flail chest complicated by respiratory failure necessitates positive pressure ventilation to internally splint the chest and ensure adequate oxygenation.

Key Concept

Appropriate trauma management relies on mechanism of injury and hemodynamic stability to differentiate between immediate surgical intervention, procedural stabilization, advanced imaging, or operative evaluation of occult injuries.
Question 1693Question →

Match each clinical exposure scenario with the most appropriate pharmacological prophylaxis or empiric antimicrobial regimen.

Click a left item, then click its matching right item

Items

A patient steps on a nail that punctures deeply through the rubber sole of an athletic shoe.
A patient presents with a closed-fist injury over the metacarpophalangeal joint after striking another person's mouth.
An asymptomatic university student reports sharing a dorm room with a peer just diagnosed with Neisseria meningitidis meningitis.
A hiker in New England presents after removing an engorged Ixodes scapularis tick that was attached to their thigh for 48 hours.

Matches

Show answer & explanation

Answer

Rubber shoe puncture matches with oral ciprofloxacin; human bite matches with oral amoxicillin-clavulanate; meningococcal contact matches with oral rifampin; tick bite ≥36\geq 36 hours matches with single-dose oral doxycycline.
Each exposure corresponds to a highly specific, guideline-directed antimicrobial regimen to prevent or treat the most likely inoculated organisms.

Step-by-Step Solution

1
Analyze the puncture wound scenario.
Recognize the risk of Pseudomonas aeruginosa from rubber-soled shoes.
Pseudomonas thrives in the moist environment of athletic shoes and requires targeted fluoroquinolone coverage like ciprofloxacin.
2
Evaluate the human bite (clenched-fist) injury.
Identify the need to cover Eikenella corrodens and oral anaerobes.
Amoxicillin-clavulanate provides excellent coverage for the typical oral flora inoculated during fight bites.
3
Assess the meningococcal exposure.
Determine that close household/dormitory contacts need immediate prophylaxis.
Rifampin (twice daily for 2 days) eradicates nasopharyngeal carriage to prevent secondary symptomatic cases.
4
Review the tick exposure parameters.
Confirm criteria for Lyme prophylaxis: Ixodes tick, endemic area, attached ≥36\geq 36 hours.
A single dose of doxycycline effectively prevents Lyme disease if given within 72 hours of tick removal.

Key Concept

Appropriate targeted antimicrobial prophylaxis and empiric therapy for specific high-risk pathogen exposures.
Estimated Time:1m 30s
Question 1694Question →

Match each high-resolution esophageal manometry (HRM) profile to its corresponding pathophysiologic diagnosis according to the Chicago Classification.

Click a left item, then click its matching right item

Items

Elevated integrated relaxation pressure (IRP), 100% failed peristalsis, and pan-esophageal pressurization in ≥20% of swallows.
Normal integrated relaxation pressure (IRP) with premature contractions (reduced distal latency < 4.5 seconds) in ≥20% of swallows.
Elevated integrated relaxation pressure (IRP), 100% failed peristalsis, and no significant intraesophageal pressurization.
Normal integrated relaxation pressure (IRP) with at least 20% of swallows demonstrating extremely vigorous, hypercontractile waves (Distal Contractile Integral > 8,000 mmHg·s·cm).
Normal or low integrated relaxation pressure (IRP) with complete absence of peristalsis in the smooth muscle portion and a resting lower esophageal sphincter pressure < 10 mmHg.

Matches

Show answer & explanation

Answer

The correct matches align each specific high-resolution manometry parameter (IRP, distal latency, DCI, and peristaltic integrity) with its precise motility disorder as defined by the Chicago Classification.
High-resolution manometry must be interpreted algorithmically according to the Chicago Classification. The first branch point is the Integrated Relaxation Pressure (IRP). An elevated IRP signifies an outflow obstruction, typically achalasia; among these, pan-esophageal pressurization distinguishes Type II from Type I. If the IRP is normal, the focus shifts to peristaltic timing and vigor: abnormal prematurity (distal latency < 4.5s) defines Distal Esophageal Spasm, excessive vigor (DCI > 8,000) defines Jackhammer Esophagus, and entirely absent contractility with a weak sphincter defines the scleroderma esophagus.

Step-by-Step Solution

1
Evaluate the Integrated Relaxation Pressure (IRP) for each manometry profile to determine the presence of an outflow obstruction.
Profiles 1 and 3 present with an elevated IRP, indicating achalasia. Profiles 2, 4, and 5 exhibit a normal or low IRP, ruling out achalasia.
An elevated IRP is the defining hallmark of lower esophageal sphincter relaxation failure, which is required for a definitive diagnosis of achalasia.
2
Differentiate between the profiles with an elevated IRP (Profiles 1 and 3).
Profile 1 exhibits pan-esophageal pressurization (Type II Achalasia), whereas Profile 3 lacks this pressurization (Type I Achalasia).
Type II achalasia maintains sufficient longitudinal muscle tone to generate compartmentalized pressurization against a non-relaxing sphincter, distinguishing it from the passive, dilated esophagus of Type I.
3
Assess the profiles with a normal IRP for abnormalities in contraction timing or vigor (Profiles 2 and 4).
Profile 2 demonstrates premature contractions (Distal Esophageal Spasm). Profile 4 demonstrates extreme hypercontractility (Jackhammer Esophagus).
Premature contractions (reduced distal latency) reflect an inhibitory nerve defect, while an excessively high DCI (>8,000) reflects hyperactive excitatory cholinergic stimulation.
4
Analyze the remaining profile displaying a normal/low IRP coupled with absent peristalsis (Profile 5).
Profile 5 describes absent peristalsis and a hypotensive lower esophageal sphincter, perfectly matching Scleroderma Esophagus.
Systemic sclerosis preferentially replaces the smooth muscle of the distal two-thirds of the esophagus with collagenous fibrosis, leading to profound hypotonia and complete loss of peristalsis.

Key Concept

Interpretation of High-Resolution Esophageal Manometry (Chicago Classification v4.0)
Question 1695Question →

Match each patient's clinical presentation with the most likely corresponding finding on a peripheral blood smear.

Click a left item, then click its matching right item

Items

A 54-year-old asymptomatic man with an incidentally discovered leukocyte count of 65,000/mm365,000/\text{mm}^3 (predominantly mature-appearing small lymphocytes) and bilateral painless cervical lymphadenopathy.
A 23-year-old Mediterranean man with lifelong mild, asymptomatic microcytic anemia, normal iron studies, and an elevated hemoglobin A2A_2 fraction.
A 31-year-old man who develops scleral icterus, dark urine, and a rapid drop in hemoglobin two days after initiating trimethoprim-sulfamethoxazole for a skin infection.
A 72-year-old woman presenting with progressive fatigue, a mean corpuscular volume of 118 fL118 \text{ fL}, and new-onset loss of vibratory sensation in her lower extremities.

Matches

Show answer & explanation

Answer

Chronic Lymphocytic Leukemia pairs with smudge cells; beta-thalassemia trait pairs with target cells; G6PD deficiency pairs with bite cells; and Vitamin B12 deficiency pairs with hypersegmented neutrophils.
Each peripheral smear finding is generated by a specific mechanism unique to the paired disease: mechanical disruption of fragile B-cells (smudge cells in CLL), relative membrane excess (target cells in thalassemia), splenic macrophage pitting of Heinz bodies (bite cells in G6PD deficiency), and impaired DNA synthesis delaying nuclear lobation (hypersegmented neutrophils in Vitamin B12 deficiency).

Step-by-Step Solution

1
Diagnose the underlying condition for each clinical vignette.
Vignette 1 is Chronic Lymphocytic Leukemia (CLL). Vignette 2 is beta-thalassemia minor. Vignette 3 is G6PD deficiency. Vignette 4 is Vitamin B12 deficiency.
Accurate diagnosis is required before associating the pathophysiologic mechanism with its corresponding smear finding.
2
Recall the mechanism of red or white blood cell morphologic changes in each identified condition.
CLL involves fragile neoplastic lymphocytes. Beta-thalassemia involves decreased hemoglobin synthesis resulting in relative membrane excess. G6PD deficiency involves oxidative denaturation of hemoglobin. B12 deficiency involves impaired DNA synthesis.
Understanding the mechanism explains the physical appearance of the cells under microscopy.
3
Map the mechanism to the specific named peripheral smear finding.
Fragile lymphocytes = smudge cells; membrane excess = target cells; pitted Heinz bodies = bite cells; delayed nuclear maturation = hypersegmented neutrophils.
This completes the pairing for the final answer.

Key Concept

Peripheral blood smear findings reflect specific underlying pathophysiologic mechanisms in hematologic disorders.
Estimated Time:1m 30s
Question 1696Question →

Match each clinical and diagnostic presentation to the most likely hepatic or biliary disorder.

Click a left item, then click its matching right item

Items

Primary biliary cholangitis (PBC)
Primary sclerosing cholangitis (PSC)
Autoimmune hepatitis
Wilson disease

Matches

Show answer & explanation

Answer

Primary biliary cholangitis matches the presentation with positive antimitochondrial antibodies (AMA). Primary sclerosing cholangitis matches the patient with ulcerative colitis and bile duct stricturing. Autoimmune hepatitis matches the patient with elevated IgG and anti-smooth muscle antibodies. Wilson disease matches the young adult with neurologic symptoms and low ceruloplasmin.
Each specific diagnosis has a hallmark clinical vignette. Primary biliary cholangitis is characterized by AMA positivity in a middle-aged woman with pruritus. Primary sclerosing cholangitis is characterized by biliary stricturing and a strong association with inflammatory bowel disease. Autoimmune hepatitis features a hepatocellular injury pattern with ASMA positivity. Wilson disease is defined by impaired copper excretion leading to hepatic and neurologic manifestations alongside low ceruloplasmin.

Step-by-Step Solution

1
Analyze the autoantibody and laboratory profile in each clinical vignette.
Identified distinguishing markers: AMA for the first case, MRCP findings + ulcerative colitis for the second, ASMA + elevated IgG for the third, and low ceruloplasmin for the fourth.
Hepatic and biliary diseases have specific, highly sensitive and specific diagnostic associations that differentiate them.
2
Correlate the diagnostic findings and demographics with the specific liver pathologies.
Paired AMA with PBC; paired the 'beading' of bile ducts and UC history with PSC; paired ASMA with Autoimmune hepatitis; paired low ceruloplasmin and neurologic symptoms with Wilson disease.
Matching the classic pathophysiology and epidemiology to the clinical presentation confirms the exact diagnoses.

Key Concept

Clinical presentation and specific diagnostic markers of autoimmune, cholestatic, and metabolic liver diseases.
Estimated Time:1m 30s
Question 1697Question →

Match the following Hepatitis B serologic profiles obtained during routine screening or acute evaluation to their most accurate clinical interpretation.

Click a left item, then click its matching right item

Items

HBsAg negative, Anti-HBs positive, Anti-HBc IgG positive
HBsAg positive, Anti-HBs negative, Anti-HBc IgM positive, HBeAg positive
HBsAg positive, Anti-HBs negative, Anti-HBc IgG positive, HBeAg negative, normal ALT
HBsAg negative, Anti-HBs negative, Anti-HBc IgM positive
HBsAg negative, Anti-HBs positive, Anti-HBc negative

Matches

Show answer & explanation

Answer

Profile 1 matches natural immunity; Profile 2 matches acute infection; Profile 3 matches inactive carrier; Profile 4 matches the window period; Profile 5 matches vaccination immunity.
Accurate interpretation of Hepatitis B serology requires stepwise analysis: HBsAg identifies active disease, Anti-HBc distinguishes acute (IgM) from chronic/resolved (IgG) exposure, and Anti-HBs identifies immunity. The absence of HBsAg and Anti-HBs with positive Anti-HBc IgM defines the window period. Isolated Anti-HBs defines vaccination.

Step-by-Step Solution

1
Evaluate the HBsAg status for each profile.
Positive HBsAg indicates active infection (acute or chronic). Negative HBsAg indicates immunity, resolution, or the window period.
HBsAg is the hallmark of active viral presence.
2
Differentiate between sources of immunity in HBsAg-negative profiles.
Profile 5 has isolated Anti-HBs, indicating vaccination. Profile 1 has both Anti-HBs and Anti-HBc IgG, indicating natural immunity from prior exposure.
Vaccines only contain surface antigen, while natural infection exposes the host to both surface and core antigens.
3
Differentiate acute versus chronic states in HBsAg-positive profiles.
Profile 2 has Anti-HBc IgM, marking acute infection. Profile 3 has Anti-HBc IgG with normal ALT and negative HBeAg, marking an inactive chronic carrier.
IgM is an acute phase reactant, whereas IgG indicates a chronic state (persisting >6 months).
4
Identify the pattern lacking both HBsAg and Anti-HBs.
Profile 4 only shows Anti-HBc IgM, which is classic for the 'window period'.
During this phase, surface antigen has been cleared, but surface antibodies are still forming and bound in complexes, leaving Anti-HBc IgM as the sole marker.

Key Concept

Interpretation of Hepatitis B Serologic Markers
Question 1698Question →

Match each central hemodynamic profile obtained via pulmonary artery (Swan-Ganz) catheterization to its most likely underlying pathophysiological etiology.

Click a left item, then click its matching right item

Items

Elevated right atrial pressure (RAP), normal pulmonary capillary wedge pressure (PCWP), decreased cardiac index (CI), and increased systemic vascular resistance (SVR).
Equalization of elevated RAP and PCWP, decreased CI, increased SVR, and an absent y-descent on the right atrial pressure waveform.
Equalization of elevated RAP and PCWP, normal or mildly decreased CI, increased SVR, and prominent x and y descents (dip-and-plateau pattern) on the right atrial pressure waveform.
Elevated RAP, markedly elevated PCWP with prominent, early v-waves, decreased CI, and increased SVR.
Normal to low RAP, low PCWP, increased CI, decreased SVR, and elevated mixed venous oxygen saturation (SvO2SvO_2).

Matches

Show answer & explanation

Answer

Proper matching requires analyzing equalization of diastolic pressures, identifying waveform abnormalities (x and y descents, v-waves), and differentiating cardiogenic/obstructive profiles from distributive profiles based on the cardiac index and systemic vascular resistance.
Each hemodynamic profile contains key discriminators: isolated elevated RAP (RV infarct), absent y-descent with equalized pressures (tamponade), prominent y-descent with equalized pressures (constrictive pericarditis), prominent v-waves (acute MR), and high CI with low SVR (distributive shock).

Step-by-Step Solution

1
Differentiate the hyperdynamic shock profile from low-output shock profiles.
The profile with increased cardiac index and decreased systemic vascular resistance uniquely identifies early distributive shock.
Cardiogenic and obstructive shock states exhibit a low cardiac index and a compensatory high systemic vascular resistance.
2
Evaluate the relationship between right and left-sided filling pressures in the low-output profiles.
The profile with elevated right atrial pressure but normal pulmonary capillary wedge pressure points to isolated right heart failure (Right Ventricular Infarction).
If the left ventricle was failing, PCWP would be markedly elevated. Clear lungs and normal PCWP with high RAP localize the failure to the right ventricle.
3
Analyze atrial waveform descents in the profiles demonstrating equalization of pressures (RAP = PCWP).
An absent y-descent identifies cardiac tamponade, whereas prominent x and y descents (dip and plateau) identify constrictive pericarditis.
Tamponade continuously restricts diastolic filling (no y-descent), while constriction allows initial rapid filling until the heart hits the rigid pericardium (prominent y-descent).
4
Identify specific abnormal waveform additions in the setting of elevated left-sided pressures.
Giant v-waves on the pulmonary capillary wedge pressure tracing confirm acute papillary muscle rupture (severe mitral regurgitation).
The v-wave represents left atrial filling during ventricular systole; severe regurgitation amplifies this wave profoundly.

Key Concept

Interpretation of pulmonary artery catheter hemodynamics and waveform morphologies in differentiating specific etiologies of shock.
Question 1699Question →

Match each set of laboratory findings from the evaluation of the hypothalamic-pituitary-adrenal (HPA) axis to the most likely underlying pathophysiologic diagnosis.

Click a left item, then click its matching right item

Items

Low morning serum cortisol, elevated plasma ACTH, and absent cortisol rise following cosyntropin administration
Low morning serum cortisol, inappropriately low-normal plasma ACTH, and blunted cortisol rise following cosyntropin administration
Elevated 24-hour urine free cortisol, undetectable plasma ACTH, and failure of serum cortisol to suppress with 8 mg dexamethasone
Elevated 24-hour urine free cortisol, normal-to-high plasma ACTH, and >50% suppression of serum cortisol with 8 mg dexamethasone
Elevated 24-hour urine free cortisol, markedly elevated plasma ACTH, and failure of serum cortisol to suppress with 8 mg dexamethasone

Matches

Show answer & explanation

Answer

The correct matches align the laboratory patterns with their respective HPA axis defects: primary adrenal insufficiency (L1 to R1), secondary adrenal insufficiency (L2 to R2), ACTH-independent hypercortisolism (L3 to R3), Cushing disease (L4 to R4), and ectopic ACTH secretion (L5 to R5).
Matching these conditions requires tracing physiologic negative feedback loops. In primary adrenal failure, lack of cortisol removes negative feedback, elevating ACTH. In secondary failure, the absence of ACTH causes downstream cortisol deficiency and subsequent adrenal atrophy. In hypercortisolism, the source is isolated by checking ACTH dependence (adrenal tumors suppress ACTH; central/ectopic sources drive it) and checking the response to high-dose dexamethasone (pituitary adenomas retain limited feedback sensitivity; ectopic tumors do not).

Step-by-Step Solution

1
Analyze cortisol and ACTH levels to determine the primary defect in hypocortisolic states.
Low cortisol with elevated ACTH indicates a primary adrenal defect. Low cortisol with inappropriately normal or low ACTH indicates a central (pituitary/hypothalamic) defect.
Intact feedback mechanisms will cause ACTH to rise if the adrenal gland fails, but ACTH will be inappropriately low if the pituitary is the source of the failure.
2
Evaluate the cosyntropin (synthetic ACTH) stimulation test results for the hypocortisolic patterns.
An absent response confirms adrenal destruction (primary). A blunted response in the setting of low ACTH confirms adrenal atrophy secondary to chronic lack of endogenous ACTH stimulation.
Cosyntropin directly stimulates the adrenal cortex. A diseased or chronically atrophied adrenal cortex cannot mount a normal cortisol response.
3
Analyze baseline ACTH levels in the hypercortisolic states.
Suppressed ACTH indicates ACTH-independent hypercortisolism, typically an adrenal source. Normal to high ACTH indicates ACTH-dependent hypercortisolism, either from a pituitary or ectopic source.
Autonomous cortisol production by the adrenal gland exerts negative feedback, fully suppressing normal pituitary ACTH.
4
Use the high-dose dexamethasone suppression test to differentiate ACTH-dependent hypercortisolism causes.
Suppression of cortisol confirms a pituitary source which retains partial feedback sensitivity. Lack of suppression confirms an ectopic source which is completely autonomous.
Pituitary adenomas maintain some functional glucocorticoid receptors and respond to high doses of exogenous steroids, while ectopic neuroendocrine tumors do not.

Key Concept

Diagnostic interpretation of the Hypothalamic-Pituitary-Adrenal (HPA) Axis
Estimated Time:2m 0s
Question 1700Question →

Determine the most appropriate definitive surgical or procedural management for each of the following gastrointestinal and colorectal pathologies.

Click a left item, then click its matching right item

Items

A 2.5-cm neuroendocrine (carcinoid) tumor located at the base of the appendix.
A 0.8-cm neuroendocrine (carcinoid) tumor located at the tip of the appendix without mesoappendiceal involvement.
Familial adenomatous polyposis (FAP) with hundreds of colonic adenomas and severe dysplasia in the rectum.
A completely excised pedunculated colonic polyp showing carcinoma in situ (high-grade dysplasia) with a 3-mm clear margin.

Matches

Show answer & explanation

Answer

Tumors >2 cm or at the appendiceal base mandate right hemicolectomy. Tumors <1 cm at the tip require only appendectomy. FAP with severe rectal dysplasia requires total proctocolectomy. Completely excised carcinoma in situ requires only routine colonoscopy surveillance.
The appropriate surgical management of these gastrointestinal pathologies relies on accurately assessing the risk of metastasis or future malignancy. Appendiceal tumors >2 cm or at the base have high metastatic potential, requiring a right hemicolectomy. Small (<1 cm) tip tumors do not require extended resection. FAP with rectal dysplasia guarantees future cancer without total proctocolectomy. Carcinoma in situ cannot metastasize, making endoscopic resection sufficient.

Step-by-Step Solution

1
Analyze the size and location of the appendiceal neuroendocrine tumors.
Tumors >2 cm or at the base need right hemicolectomy; tumors <1 cm at the tip need only appendectomy.
Surgical resection extent is dictated by the risk of regional nodal metastasis.
2
Evaluate the management of FAP with rectal dysplasia.
Total proctocolectomy with ileal pouch-anal anastomosis is indicated.
Leaving the rectum in place when it has severe dysplasia poses an unacceptable risk for future rectal cancer.
3
Determine the treatment for completely excised carcinoma in situ.
Observation with colonoscopy surveillance is appropriate.
Carcinoma in situ lacks access to lymphatics, making clear margin endoscopic removal completely curative without further surgery.

Key Concept

Definitive surgical management of appendiceal neuroendocrine tumors, familial adenomatous polyposis, and malignant colonic polyps.
PreviousPage 85 / 93Next
All practice questions — USMLE Step 2 CK | Examkin