Examkin

All practice questions

8270 questions

All types8,270Multiple choice4,249Multiple select325Numeric160Matching1,849Ordering1,687
Question 3621Question →

While recovering in the surgical intensive care unit on postoperative day 1 following coronary artery bypass grafting, a 58-year-old woman experiences acute respiratory distress. Thirty minutes prior to this event, a right internal jugular central venous catheter was inserted for hemodynamic monitoring. Her blood pressure has dropped to 70/40 mmHg, and her heart rate is 135/min. On physical examination, breath sounds are absent over the right lung field, and the jugular veins are prominently distended. Which of the following is the most appropriate next step in management?

Show answer & explanation

Answer: Immediate needle thoracostomy

Answer

Immediate needle thoracostomy
The correct answer is immediate needle thoracostomy. This patient's presentation of sudden respiratory distress, obstructive shock (hypotension, tachycardia), absent unilateral breath sounds, and jugular venous distention shortly after a central venous catheter placement is the classic presentation of an iatrogenic tension pneumothorax. Because the patient is hemodynamically unstable, the diagnosis is purely clinical, and immediate decompression is required to restore venous return and cardiac output. Imaging must not delay treatment.

Step-by-Step Solution

1
Identify the primary complication from the clinical presentation.
The combination of sudden respiratory distress, hypotension, absent unilateral breath sounds, and jugular venous distention shortly after central line placement points to an iatrogenic tension pneumothorax.
Central venous catheterization carries a known risk of pleural puncture, leading to air accumulation that compresses mediastinal structures.
2
Assess the patient's hemodynamic status.
The patient is hypotensive (70/40 mmHg) and tachycardic (135/min), indicating obstructive shock.
Increased intrathoracic pressure from the tension pneumothorax severely impairs venous return to the heart, leading to cardiovascular collapse.
3
Determine the most appropriate immediate intervention.
Immediate pleural decompression is required.
In a hemodynamically unstable patient, tension pneumothorax is a clinical diagnosis that must be treated immediately with needle or tube thoracostomy, without waiting for radiographic confirmation.

Key Concept

Tension pneumothorax is a life-threatening emergency presenting with obstructive shock, absent breath sounds, and jugular venous distention; it requires immediate clinical diagnosis and pleural decompression before any imaging is performed.
Question 3622Question →

A 6868-year-old left-handed man presents to the cardiology clinic complaining of recurrent chest pain. He describes the pain as a severe, pressure-like sensation that reliably occurs when he plays tennis or performs strenuous overhead activities with his left arm. The pain completely resolves within 55 minutes of rest. Interestingly, he reports that he can walk on a treadmill for 4545 minutes without experiencing any chest discomfort. His past medical history is significant for peripheral artery disease, tobacco use disorder, and severe coronary artery disease. He underwent coronary artery bypass grafting (CABG) 1414 months ago, receiving a left internal mammary artery (LIMA) graft to the left anterior descending (LAD) artery and a saphenous vein graft to the right coronary artery.

Vital signs include a heart rate of 7272/min. Blood pressure is 152/88152/88 mmHg in the right arm and 108/68108/68 mmHg in the left arm. Physical examination reveals a distinct bruit auscultated over the left supraclavicular fossa. An electrocardiogram obtained during an episode of pain shows new ST-segment depressions in the anterior leads, which resolve completely after rest.

Which of the following is the most appropriate definitive management for this patient's underlying condition?

Show answer & explanation

Answer: Endovascular stenting of the left subclavian artery

Answer

The correct intervention is revascularization of the left subclavian artery, most commonly via endovascular stenting.
This patient's presentation is the classic description of coronary-subclavian steal syndrome, a rare but highly significant complication that can occur in patients with a prior LIMA-to-LAD bypass graft. The patient has a severe stenosis of the left subclavian artery proximal to the origin of the LIMA, which is indicated by the prominent left supraclavicular bruit and the significant blood pressure drop (>15>15 mmHg difference) in the left arm. At rest, blood flow to the arm and heart may be sufficient. However, during strenuous left arm exertion (like playing tennis), local vasodilation dramatically decreases vascular resistance in the arm. Because the proximal subclavian artery is occluded, blood flows along the path of least resistance: retrogradely from the LAD, up the LIMA, and into the distal subclavian artery to supply the exercising arm. This 'steals' blood away from the anterior myocardium, causing angina and ST-segment depressions. The hallmark clinical clue is angina provoked by upper extremity exercise but NOT by lower extremity exercise (e.g., walking on a treadmill). The definitive management is to correct the underlying inflow obstruction by revascularizing the left subclavian artery, most commonly via percutaneous transluminal angioplasty and stenting, which restores antegrade flow to both the arm and the heart.

Step-by-Step Solution

1
Analyze the symptom triggers in the context of the patient's surgical history.
The patient experiences angina exclusively during left upper extremity exertion, despite excellent tolerance for lower extremity exertion (treadmill). He has a LIMA-to-LAD graft.
This specific trigger pattern strongly suggests a localized hemodynamic issue involving the left arm circulation, rather than generalized progression of coronary artery disease.
2
Evaluate the physical examination findings.
There is a blood pressure discrepancy of >40>40 mmHg (lower in the left arm) and a left supraclavicular bruit.
These findings are diagnostic of a hemodynamically significant stenosis in the left subclavian artery proximal to the origin of the left vertebral and LIMA branches.
3
Synthesize findings to determine the underlying pathophysiology.
The patient has Coronary-Subclavian Steal Syndrome.
During left arm exercise, local vascular resistance drops. Due to the proximal subclavian stenosis, blood flows retrogradely from the LAD, up the LIMA, and into the left arm, stealing oxygenated blood from the myocardium and inducing anterior ischemia.
4
Select the definitive management strategy.
Endovascular stenting (or surgical bypass) of the left subclavian artery.
Relieving the proximal stenosis normalizes the pressure gradient, restoring normal antegrade flow down both the LIMA and the left arm, which permanently resolves the angina.

Key Concept

Coronary-Subclavian Steal Syndrome
Question 3623Question →

An adolescent boy, age 1616, presents to the triage desk reporting severe right-sided scrotal pain that awoke him from sleep approximately 9090 minutes ago. He has no prior medical history and does not report any recent sexual activity or trauma. His temperature is 37.0∘C37.0^\circ\text{C} (98.6∘F98.6^\circ\text{F}), pulse is 105/min105/\text{min}, and blood pressure is 120/75 mm Hg120/75 \text{ mm Hg}. Genitourinary examination demonstrates a diffusely swollen, markedly tender right testicle with a transverse lie, positioned notably higher than the contralateral testis. Stroking the inner aspect of the right thigh produces no testicular elevation, whereas the reflex is intact on the left side. Which of the following is the most appropriate next step in the management of this patient?

Show answer & explanation

Answer: Emergent surgical exploration

Answer

Emergent surgical exploration
The correct answer is emergent surgical exploration. This patient's presentation of sudden-onset, severe unilateral scrotal pain that awoke him from sleep, combined with a high-riding, transversely oriented testicle and an absent cremasteric reflex, is highly specific for testicular torsion. Testicular torsion is a surgical emergency caused by the twisting of the spermatic cord, leading to venous congestion and subsequent arterial compromise. Because testicular salvage rates drop significantly after 66 hours of ischemia, definitive treatment with emergent surgical exploration and bilateral orchiopexy is required immediately. In cases where the clinical suspicion is unequivocally high, diagnostic imaging must be bypassed to avoid delaying surgical care.

Step-by-Step Solution

1
Analyze the patient's symptoms and physical examination findings.
The patient has sudden-onset severe scrotal pain, a high-riding testis with a transverse lie, and an absent cremasteric reflex.
These findings must be synthesized to determine the underlying etiology of the acute scrotum.
2
Establish the most likely clinical diagnosis.
The clinical picture is highly specific for testicular torsion.
The absence of the cremasteric reflex is the most sensitive physical exam finding for testicular torsion, distinguishing it from epididymitis or torsion of the appendix testis.
3
Determine the appropriate management for highly suspected testicular torsion.
Immediate urologic consultation and surgical exploration are required.
Testicular viability decreases rapidly after 66 hours of ischemia, making immediate surgery the standard of care without delaying for imaging.

Key Concept

Patients with a high clinical suspicion for testicular torsion (characterized by sudden-onset pain, high-riding testicle, and absent cremasteric reflex) should undergo emergent surgical exploration without delay for ultrasound imaging.
Question 3624Question →

A physician evaluates a patient in the surgical triage area. The patient is a male in his late 50s with a 15-year history of poorly controlled type 2 diabetes mellitus. He presents with rapidly worsening genital pain and swelling over the past 24 hours, accompanied by high fevers and general malaise. His temperature is 39.2∘C39.2^\circ\text{C} (102.6∘F102.6^\circ\text{F}), pulse is 122/min122/\text{min}, and blood pressure is 92/58 mmHg92/58 \text{ mmHg}. Physical examination reveals a markedly edematous, erythematous scrotum and perineum. There are several patches of dark, purplish skin necrosis over the right hemiscrotum. Palpation of the affected area elicits exquisite pain along with a distinct crackling sensation beneath the skin. Laboratory studies show a leukocyte count of 24,500/μL24,500/\mu\text{L} with 15%15\% bands, and a serum glucose of 385 mg/dL385 \text{ mg/dL}. Which of the following is the most appropriate immediate next step in management?

Show answer & explanation

Answer: Emergent surgical exploration and wide debridement

Answer

Emergent surgical exploration and wide debridement
The correct action is emergent surgical exploration and wide debridement. This patient's presentation of high fever, hemodynamic instability, scrotal skin necrosis, and crepitus (subcutaneous gas) in the setting of poorly controlled diabetes is pathognomonic for Fournier gangrene. This is a fulminant necrotizing fasciitis of the perineum and external genitalia. Because the infection spreads rapidly along fascial planes and is highly lethal, the single most critical step in management is immediate surgical source control to excise all non-viable tissue. While broad-spectrum antibiotics and fluid resuscitation are initiated simultaneously, surgery must not be delayed.

Step-by-Step Solution

1
Identify the primary clinical syndrome based on vital signs and physical examination.
The patient has systemic toxicity (hypotension, fever, tachycardia, profound leukocytosis) paired with severe perineal pain, skin necrosis, and palpable crepitus.
These findings are the hallmark of necrotizing fasciitis of the perineal and genital region, known as Fournier gangrene.
2
Identify the pathophysiology and primary risk factors associated with the diagnosis.
Fournier gangrene is a rapidly progressive, polymicrobial infection that spreads along fascial planes (Colles, Dartos, and Scarpa fascia). Poorly controlled diabetes mellitus is a classic predisposing risk factor.
Understanding the aggressive spread along fascial planes dictates the urgency and extent of the required intervention.
3
Determine the most appropriate immediate next step in management for a hemodynamically unstable patient with a clinically obvious necrotizing infection.
Immediate surgical exploration and wide debridement of all necrotic tissue is required.
Surgical source control is the single most important determinant of survival in necrotizing fasciitis. Delaying surgery for any reason, including imaging or awaiting the effects of antibiotics, significantly increases mortality.

Key Concept

Fournier gangrene is a life-threatening necrotizing fasciitis of the perineum and scrotum that requires immediate surgical exploration and wide debridement; clinical diagnosis (crepitus, skin necrosis) should prompt surgery without delaying for imaging.
Question 3625Question →

While recovering on the surgical floor 24 hours after a total thyroidectomy for a large, symptomatic multinodular goiter, a patient reports the onset of a "crawling" sensation around her lips and fingertips. Vital signs show a temperature of 38.2°C (100.8°F), pulse of 92/min, respirations of 16/min, and blood pressure of 115/75 mm Hg. Examination of the neck reveals a clean, dry, and intact surgical incision without any surrounding swelling, fluctuance, or erythema. The patient's voice is normal and there is no stridor. Tapping the area just anterior to the earlobe results in brief twitching of the ipsilateral facial muscles. Laboratory results drawn earlier this morning reveal:

TestResultReference Range
Calcium, total7.2 mg/dL8.4-10.2 mg/dL
Albumin4.0 g/dL3.5-5.0 g/dL
TSH1.8 µU/mL0.5-5.0 µU/mL
Free T41.3 ng/dL0.9-1.7 ng/dL

Which of the following is the most appropriate next step in the management of this patient?

Show answer & explanation

Answer: Intravenous administration of calcium gluconate

Answer

Intravenous administration of calcium gluconate
The correct answer is the intravenous administration of calcium gluconate. This patient is presenting with classic signs of acute, symptomatic hypocalcemia, including perioral numbness, tingling in the extremities, and a positive Chvostek sign (ipsilateral facial muscle twitching when tapping the facial nerve). In the context of a recent total thyroidectomy, this is overwhelmingly likely due to inadvertent removal or devascularization of the parathyroid glands. Because she is actively symptomatic, she requires immediate intravenous calcium replacement (typically calcium gluconate) to prevent severe complications such as laryngospasm, tetany, seizures, and QT-prolongation leading to arrhythmias.

Step-by-Step Solution

1
Analyze the physical examination findings and vital signs.
The patient exhibits perioral numbness, paresthesias of the fingertips, and a positive Chvostek sign (facial muscle twitching upon tapping the facial nerve). Fever is present, but the incision is benign and the airway is secure.
Identifying these classic neurologic signs establishes a clinical suspicion for neuromuscular irritability.
2
Correlate physical findings with laboratory data.
The total serum calcium is significantly low at 7.2 mg/dL with a normal albumin, confirming true hypocalcemia. Thyroid labs are within normal limits.
Laboratory confirmation is necessary to differentiate hypocalcemia from other causes of postoperative parasthesias or neurological changes.
3
Determine the etiology based on the surgical history.
The patient is 24 hours post-total thyroidectomy. The most common cause of acute hypocalcemia in this setting is transient or permanent hypoparathyroidism due to inadvertent parathyroid gland removal or devascularization.
Connecting the surgery to the metabolic derangement guides targeted therapy.
4
Select the appropriate therapeutic intervention.
Because the patient is symptomatic (positive Chvostek sign, paresthesias), immediate intravenous calcium gluconate is required to prevent progression to tetany, seizures, or cardiac arrhythmias.
Symptomatic hypocalcemia is a medical emergency; oral calcium is insufficient for acute, symptomatic presentation.

Key Concept

Post-thyroidectomy symptomatic hypocalcemia recognition and management
Question 3626Question →

A 4646-year-old man is referred to the surgical endocrinology clinic due to refractory hypertension. His blood pressure is consistently ≥160/100\geq 160/100 mmHg despite adherence to maximum doses of amlodipine, lisinopril, and hydrochlorothiazide. Recent laboratory evaluation demonstrated a serum potassium level of 3.13.1 mEq/L. The patient has no family history of endocrine malignancies. Suspecting a primary hypersecretory disorder, the surgical team plans a comprehensive diagnostic and therapeutic pathway.

Arrange the following steps in the correct chronological sequence for the standard diagnostic workup and definitive surgical management of this patient's condition.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: (1) Measure the plasma aldosterone to renin ratio, (2) Administer a confirmatory saline infusion test, (3) Obtain an adrenal CT scan, (4) Perform adrenal venous sampling, and (5) Perform a unilateral adrenalectomy.
The surgical management of primary hyperaldosteronism (Conn syndrome) dictates a strict, step-wise algorithm to prevent inappropriate adrenalectomies. The pathway begins with case detection (screening) using the plasma aldosterone concentration to plasma renin activity ratio. If elevated, the diagnosis is confirmed by demonstrating autonomous aldosterone secretion via a suppression test (such as an intravenous saline load). Only after robust biochemical confirmation is established should anatomical imaging (adrenal CT) be performed. Crucially, in patients over 3535 to 4040 years of age, anatomical imaging alone is insufficient to guide surgical intervention because benign, non-functioning adrenal incidentalomas are extremely common. Therefore, functional lateralization with adrenal venous sampling (AVS) is mandatory to confirm that the specific adenoma visualized on CT is actually the hypersecreting source. Once unilateral secretion is functionally confirmed via AVS, a unilateral laparoscopic adrenalectomy is performed.

Step-by-Step Solution

1
Initial Screening
Measure plasma aldosterone concentration (PAC) and plasma renin activity (PRA).
Patients presenting with the triad of resistant hypertension, hypokalemia, and absence of secondary causes must first undergo case detection using the PAC/PRA ratio.
2
Biochemical Confirmation
Perform a saline infusion test or oral sodium loading test.
An elevated PAC/PRA ratio is highly sensitive but not definitive; autonomous aldosterone production must be confirmed by demonstrating failure to suppress aldosterone levels under salt-loading conditions.
3
Anatomical Imaging
Obtain an adrenal protocol CT scan.
Once primary hyperaldosteronism is biochemically confirmed, CT imaging is necessary to rule out large carcinomas and assess adrenal anatomy, though it cannot definitively distinguish functioning from non-functioning adenomas in adults.
4
Functional Lateralization
Perform bilateral adrenal venous sampling (AVS).
Because non-functioning adrenal incidentalomas are highly prevalent in patients older than 35−4035-40 years, AVS is mandatory to prove that the biochemically confirmed hyperaldosteronism is originating from the anatomically abnormal gland seen on CT.
5
Definitive Treatment
Perform a unilateral laparoscopic adrenalectomy.
Once AVS functionally confirms unilateral hypersecretion, surgical resection of the affected gland becomes the definitive, curative treatment.

Key Concept

Diagnostic and surgical management algorithm for Primary Hyperaldosteronism

Alternative Method

In highly selected cases where patients are young (<35<35 years old) with marked spontaneous hypokalemia, profound aldosterone elevation, and a clear unilateral adenoma on CT, some endocrine surgery guidelines permit proceeding to adrenalectomy without AVS. However, for a 46-year-old, AVS remains universally mandated.
Estimated Time:2m 0s
Question 3627Question →

A 62-year-old man is evaluated in the neurosurgical intensive care unit due to a sudden decline in consciousness. He underwent an uncomplicated right frontotemporal craniotomy for resection of a meningioma 48 hours ago. Over the past hour, the nurse noted that he became increasingly difficult to arouse. His temperature is 38.1°C (100.6°F), blood pressure is 180/100 mm Hg, pulse is 48/min, and respirations are 10/min and irregular. Glasgow Coma Scale score is 7 (E2, V2, M3), decreased from a baseline of 14. Neurologic examination reveals a 7-mm, unreactive right pupil and a new profound left-sided hemiparesis. The surgical incision site appears clean and intact. Which of the following is the most appropriate next step in management?

Show answer & explanation

Answer: Endotracheal intubation and administration of intravenous mannitol

Answer

Endotracheal intubation and administration of intravenous mannitol
The correct answer combines the two most urgent priorities in a patient with active uncal herniation and a GCS less than 8: securing the airway and medically reducing intracranial pressure. The patient's Cushing triad (hypertension, bradycardia, irregular respirations), declining GCS, ipsilateral fixed and dilated pupil (due to oculomotor nerve compression), and contralateral hemiparesis (due to cerebral peduncle compression) are classic signs of uncal herniation. Endotracheal intubation protects the airway and allows for controlled ventilation, while mannitol (an osmotic diuretic) acutely reduces cerebral edema and intracranial pressure, buying critical time for diagnostic imaging and surgical intervention.

Step-by-Step Solution

1
Analyze the patient's vital signs and neurologic examination.
The patient has Cushing triad (hypertension, bradycardia, irregular respirations), a declining Glasgow Coma Scale score of 7, a dilated right pupil, and left-sided hemiparesis.
These findings are pathognomonic for right-sided uncal herniation, a life-threatening neurologic emergency often caused by postoperative hemorrhage or edema.
2
Determine the most critical immediate intervention.
The patient requires immediate airway protection and medical reduction of intracranial pressure before any diagnostic imaging is performed.
A GCS under 8 combined with irregular respirations necessitates immediate intubation to secure the airway. Mannitol is an osmotic diuretic that rapidly decreases cerebral edema, buying critical time for a subsequent CT scan and definitive surgical decompression.

Key Concept

In patients with active uncal herniation, securing the airway and administering osmotic therapy take precedence over diagnostic imaging.
Estimated Time:1m 0s
Question 3628Question →

A clinical research team investigates the potential link between maternal exposure to agricultural pesticides and the occurrence of neural tube defects. They identify 40 infants born with neural tube defects and 120 healthy infants born at the same regional hospital over a two-year period. The researchers subsequently review maternal health records and conduct structured interviews regarding residential history during early pregnancy. The data indicate that 30 mothers of the affected infants and 30 mothers of the healthy infants lived within one mile of active agricultural zones where pesticides were regularly applied. Which of the following values best estimates the association between maternal pesticide exposure and neural tube defects in this study?

Show answer & explanation

Answer: 9.0

Answer

9.0
The study described is a case-control study because participants were identified based on their disease status (neural tube defects vs. healthy) rather than their exposure status. In a case-control study, the baseline incidence of the disease in the population is not known because the researchers artificially set the number of cases and controls. Therefore, relative risk cannot be directly calculated. The appropriate measure of association is the exposure odds ratio, which compares the odds of exposure among cases to the odds of exposure among controls. This is calculated as (a/c)/(b/d)(a/c) / (b/d). In this scenario, the odds of pesticide exposure among cases is 30/10=330/10 = 3, and the odds of exposure among controls is 30/90=1/330/90 = 1/3. Dividing these odds yields an odds ratio of 3/(1/3)=9.03 / (1/3) = 9.0.

Step-by-Step Solution

1
Identify the study design.
The study selected participants based on outcome (neural tube defects vs. healthy), making it a case-control study.
Study design dictates which statistical measure of association can be used.
2
Determine the appropriate measure of association.
Odds ratio (OR).
Relative risk and absolute risk reduction cannot be calculated in case-control studies because true incidence is unknown.
3
Extract the data to determine exposure odds for cases.
Among the 40 cases, 30 were exposed and 10 were unexposed. The odds of exposure = 30/10=330 / 10 = 3.
Needed for the numerator of the OR equation.
4
Extract the data to determine exposure odds for controls.
Among the 120 controls, 30 were exposed and 90 were unexposed. The odds of exposure = 30/90=1/330 / 90 = 1/3.
Needed for the denominator of the OR equation.
5
Calculate the odds ratio.
OR=31/3=9.0OR = \frac{3}{1/3} = 9.0.
This yields the final measure of association.

Key Concept

The odds ratio is the appropriate measure of association for a case-control study and is calculated by dividing the odds of exposure among cases by the odds of exposure among controls.
Question 3629Question →

Match each clinical presentation to its most likely neurosurgical diagnosis.

Click a left item, then click its matching right item

Items

A 22-year-old struck in the head with a baseball presents with brief loss of consciousness, a lucid interval, and subsequent rapid neurological decline.
An 81-year-old with a history of falls presents with insidious onset of confusion, headache, and a crescent-shaped hyperdensity on head CT.
A 45-year-old presents to the emergency department with the sudden onset of a 'thunderclap' headache, photophobia, and nuchal rigidity.
A 60-year-old man involved in a rear-end motor vehicle collision develops bilateral upper extremity weakness with relative sparing of the lower extremities.

Matches

Show answer & explanation

Answer

The lucid interval points to an epidural hematoma. The elderly patient with a crescent-shaped CT finding has a subdural hematoma. The 'thunderclap' headache represents a subarachnoid hemorrhage. The upper extremity-predominant weakness after a rear-end collision indicates central cord syndrome.
Each vignette represents a highly classic presentation of a distinct neurosurgical condition. Recognizing these 'textbook' patterns is essential for rapid diagnosis and management on the USMLE Step 2 exam.

Step-by-Step Solution

1
Analyze the first vignette regarding the 22-year-old with a lucid interval.
The classic 'lucid interval' after trauma suggests an epidural hematoma.
Tear of the middle meningeal artery leads to rapid arterial bleeding after initial recovery.
2
Analyze the second vignette regarding the 81-year-old with a crescent-shaped CT finding.
This presentation is characteristic of a subdural hematoma.
Tearing of bridging veins in an elderly patient causes slow venous bleeding that conforms to the shape of the skull.
3
Analyze the third vignette regarding the 45-year-old with a 'thunderclap' headache.
This is the pathognomonic presentation for a subarachnoid hemorrhage.
A ruptured aneurysm releases arterial blood directly into the subarachnoid space, causing sudden severe meningeal irritation.
4
Analyze the fourth vignette regarding the 60-year-old with upper extremity weakness.
This pattern of weakness following a hyperextension injury describes central cord syndrome.
The cervical spinal cord's central gray matter, which disproportionately innervates the upper extremities, is injured during hyperextension, especially with underlying spondylosis.

Key Concept

Diagnosis of common neurosurgical emergencies based on classic clinical presentations.
Question 3630Question →

A 72-year-old man is brought to the emergency department by his daughter due to sudden-onset, severe right leg pain that began 2 hours ago. He has a history of hypertension, type 2 diabetes mellitus, and atrial fibrillation. He is prescribed apixaban but admits to missing several doses over the past week. On physical examination, the right lower extremity is pale and cool to the touch from the mid-thigh down. Femoral, popliteal, and pedal pulses are nonpalpable on the right, while they are 2+ on the left. The patient has decreased sensation over the dorsum of his right foot and exhibits mild weakness when asked to dorsiflex his toes. Arrange the following steps in the most appropriate chronological sequence for the evaluation and management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: Evaluate with Doppler, administer heparin, obtain angiography, and perform surgical embolectomy.
The patient presents with Rutherford category IIb (immediately threatened) acute limb ischemia (ALI), likely due to a thromboembolism secondary to unmedicated atrial fibrillation. The management sequence must be rapid and systematic to prevent irreversible limb loss. First, the clinical diagnosis is confirmed and categorized using a bedside continuous-wave Doppler to check for arterial and venous signals. Second, systemic anticoagulation with an intravenous heparin bolus is immediately initiated to prevent further clot propagation and preserve the microvascular bed; this is a critical step that must not be delayed for any tests. Third, while revascularization is emergent, an angiographic study (either a rapidly obtained CTA or an on-table intraoperative angiogram) is performed to map the arterial anatomy and pinpoint the occlusion. Finally, definitive treatment is achieved through emergent surgical embolectomy or bypass revascularization to restore blood flow.

Step-by-Step Solution

1
Perform physical examination including bedside continuous-wave Doppler ultrasound.
Confirms Rutherford category IIb acute limb ischemia (inaudible arterial signals, audible venous signals).
Establishes the clinical diagnosis and severity, which dictates the immediate urgency of treatment.
2
Administer an intravenous bolus of unfractionated heparin.
Achieves immediate systemic anticoagulation.
Prevents further clot propagation in the low-flow state distal to the occlusion, preserving the microcirculation while awaiting imaging and surgery.
3
Obtain an angiographic study (CTA or on-table angiography).
Delineates the arterial anatomy and identifies the exact level of the embolus or thrombus.
Provides the anatomical roadmap necessary for planning the specific surgical or endovascular revascularization approach.
4
Perform emergent surgical arterial embolectomy or revascularization.
Restores arterial perfusion to the ischemic limb.
Salvages the immediately threatened limb, preventing irreversible tissue necrosis and the need for amputation.

Key Concept

In patients with acute limb ischemia (ALI), immediate systemic anticoagulation with heparin is indicated as soon as the clinical diagnosis is established, prior to obtaining confirmatory diagnostic imaging, to prevent thrombus propagation.
Question 3631Question →

A 2424-year-old man is brought to the emergency department after colliding with a tree while downhill skiing. He reports severe, continuous pain in his right flank and right upper quadrant. His temperature is 37.1∘37.1^\circ C (98.8∘98.8^\circ F), blood pressure is 118/76118/76 mmHg, pulse is 9292/min, and respirations are 1616/min. Physical examination reveals a 1515-cm area of ecchymosis over the right flank with marked tenderness to palpation. The abdomen is soft without rebound tenderness or guarding. Urinalysis demonstrates gross hematuria. A focused assessment with sonography for trauma (FAST) is negative for intraperitoneal free fluid. Computed tomography of the abdomen and pelvis with intravenous contrast reveals a 3.53.5-cm laceration of the right kidney that extends deep into the renal medulla and collecting system. Delayed-phase imaging demonstrates pooling of contrast medium in the perirenal space. There is a moderate, non-expanding perirenal hematoma, but no evidence of active arterial extravasation (blush). Which of the following is the most appropriate next step in management?

Show answer & explanation

Answer: Hospital admission for bed rest and serial hemodynamic monitoring

Answer

The most appropriate next step is hospital admission for bed rest and serial hemodynamic monitoring.
The correct management is hospital admission for bed rest and serial hemodynamic monitoring. This patient has sustained a blunt Grade IV renal injury, characterized by a parenchymal laceration extending into the collecting system with resulting urinary extravasation. A high-yield and frequently tested principle in urologic trauma is that hemodynamic stability—not the grade of the injury—drives the decision for surgery. In the absence of hemodynamic instability, expanding/pulsatile hematoma, or active arterial extravasation, even high-grade renal injuries (Grades III-V) with urinary leaks are managed conservatively. The contained retroperitoneal space allows most urinary extravasations to heal spontaneously without surgical or endoscopic intervention.

Step-by-Step Solution

1
Assess the patient's hemodynamic status and overall trauma survey.
The patient is hemodynamically stable (BP 118/76118/76, HR 9292) with a negative FAST exam, ruling out immediate life-threatening intraperitoneal hemorrhage.
Hemodynamic stability dictates whether a trauma patient proceeds to immediate surgical exploration or advanced imaging.
2
Interpret the CT scan findings to grade the renal injury.
The CT shows a 3.53.5-cm laceration extending into the collecting system with urinary extravasation but no active arterial bleeding, classifying this as an AAST Grade IV renal injury.
Accurate grading of the renal injury determines the specific management algorithm.
3
Select the appropriate intervention based on stability and injury grade.
Because the patient is stable and lacks active arterial hemorrhage, conservative management is indicated despite the presence of urinary extravasation.
Over 90%90\% of blunt renal injuries, including Grade IV injuries with urinary leaks, resolve spontaneously with conservative management (bed rest, observation, serial hematocrits).

Key Concept

Hemodynamically stable blunt renal trauma, including high-grade injuries with urinary extravasation, should initially be managed conservatively with bed rest and observation.
Estimated Time:1m 30s
Question 3632Question →

A 28-year-old female presents for a well-woman visit to discuss family planning. She was diagnosed with polycystic ovary syndrome (PCOS) three years ago, characterized by oligomenorrhea—with menses occurring every 3 to 5 months—and hirsutism. Her medical history is also significant for frequent headaches, which she describes as severe, throbbing pain preceded by scintillating scotomas. These headaches occur roughly once every two months, and she takes sumatriptan for abortive relief. Her body mass index is 34 kg/m². Vital signs show a blood pressure of 118/76 mm Hg and a heart rate of 76/min. Physical examination demonstrates thick, dark hair growth on her chin and upper lip. A urine pregnancy test is negative. She is in a long-term monogamous relationship, does not wish to conceive, and requests a reliable contraceptive that will simultaneously reduce her risk of developing endometrial hyperplasia.

Which of the following is the most appropriate management for this patient?

Show answer & explanation

Answer: Insertion of a levonorgestrel-releasing intrauterine device

Answer

Insertion of a levonorgestrel-releasing intrauterine device
The levonorgestrel-releasing intrauterine device is the optimal choice because it releases a steady, localized dose of progestin that effectively thins the endometrial lining, protecting the patient from endometrial hyperplasia caused by the chronic anovulation (unopposed estrogen) of polycystic ovary syndrome. Crucially, as a progestin-only method, it is safe to use in patients with a history of migraine with aura, completely avoiding the elevated ischemic stroke risk associated with systemic estrogen.

Step-by-Step Solution

1
Identify the patient's dual management goals based on her history.
The patient requires highly effective contraception and progestin therapy to protect her endometrium from hyperplasia caused by chronic anovulation in PCOS.
Patients with PCOS have unopposed estrogen stimulation of the endometrium, significantly increasing their risk for endometrial hyperplasia and carcinoma.
2
Evaluate the patient's medical comorbidities against the WHO Medical Eligibility Criteria (MEC) for contraceptive use.
The patient has a history of migraines with scintillating scotomas (migraine with aura), which categorizes any estrogen-containing contraceptive as MEC Category 4 (absolute contraindication).
Combined hormonal contraceptives increase the already elevated risk of ischemic stroke in patients who suffer from migraines with aura.
3
Select the optimal therapy that fulfills both goals without violating MEC safety guidelines.
A progestin-only method, specifically the levonorgestrel-releasing intrauterine device, is chosen.
It thins the endometrium effectively (preventing hyperplasia), provides top-tier contraception, and is safe (MEC Category 2) for use in women with migraine with aura.

Key Concept

Estrogen-containing contraceptives are absolutely contraindicated (WHO MEC Category 4) in patients with migraine with aura; therefore, progestin-only methods like the levonorgestrel IUD are the safest choice to provide both contraception and endometrial protection in patients with PCOS.
Question 3633Question →

Match each clinical presentation below with the most appropriate definitive surgical intervention.

Click a left item, then click its matching right item

Items

Incidental finding on abdominal imaging of a 3.2 cm exophytic solid mass on the lower pole of the kidney in a healthy adult.
Intermittent episodes of severe unilateral flank pain associated with heavy fluid intake; imaging reveals isolated marked hydronephrosis without hydroureter.
Evaluation for a painless, firm hemiscrotal swelling reveals a hypoechoic, highly vascular intratesticular lesion on ultrasonography.
Recurrent episodes of acute urinary retention in an older adult who remains symptomatic despite dual medical therapy; prostate volume is estimated at 45 mL.

Matches

Show answer & explanation

Answer

The correct matches align each distinct urologic pathology with its gold-standard surgical management: small renal mass to partial nephrectomy, UPJ obstruction to pyeloplasty, testicular tumor to radical inguinal orchiectomy, and medically refractory BPH to TURP.
Each clinical scenario presents a classic indication for a specific urologic surgery. Nephron-sparing surgery is preferred for small renal masses. UPJ obstruction requires pyeloplasty. Testicular cancer necessitates an inguinal approach to avoid lymphatic seeding. Refractory BPH of moderate size is best managed with TURP.

Step-by-Step Solution

1
Analyze the first presentation (3.2 cm exophytic renal mass).
Identified as a stage T1a renal tumor.
Masses under 4 cm that are exophytic are prime candidates for nephron-sparing surgery.
2
Analyze the second presentation (hydronephrosis without hydroureter, pain with fluid intake).
Identified as ureteropelvic junction (UPJ) obstruction.
The lack of distal ureteral dilation localizes the obstruction to the UPJ, and dietzel syndrome (pain with diuresis) is a classic finding, requiring reconstruction.
3
Analyze the third presentation (painless, solid intratesticular mass).
Identified as highly suspicious for primary testicular malignancy.
Solid intratesticular masses require extirpation via the inguinal route to prevent altering the lymphatic drainage pattern.
4
Analyze the fourth presentation (refractory urinary retention, 45 mL prostate).
Identified as medically refractory benign prostatic hyperplasia.
Surgical de-obstruction is indicated; a 45 mL volume is well-suited for a standard transurethral approach rather than an open or simple prostatectomy.

Key Concept

Definitive surgical management of common urologic pathologies
Question 3634Question →

A 55-year-old woman is brought to the emergency department from a nursing facility due to fever, severe left-sided back pain, and altered mental status. Her blood pressure is 85/50 mmHg, heart rate is 122/min, and temperature is 39.4°C (102.9°F). Laboratory studies show a leukocyte count of 19,000/mm³. A non-contrast CT scan of the abdomen and pelvis reveals an 8-mm radiopaque calculus in the proximal left ureter with associated moderate hydroureteronephrosis and perinephric stranding. Arrange the following management steps in the most appropriate chronological sequence for this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence is: 1) Intravenous fluids and broad-spectrum antibiotics, 2) Urgent placement of a percutaneous nephrostomy tube or ureteral stent, 3) Definitive ureteroscopic stone extraction, and 4) Outpatient 24-hour urine collection.
In cases of obstructive pyelonephritis with sepsis, the strict chronological order of management is: First, initial medical stabilization (intravenous fluids and broad-spectrum antibiotics); Second, emergent source control by draining the infected system (percutaneous nephrostomy or ureteral stent); Third, delayed definitive management of the obstructing stone (lithotripsy) once the infection has cleared; and finally, long-term preventative care (metabolic evaluation) in the outpatient setting.

Step-by-Step Solution

1
Identify the primary clinical emergency in the presentation.
The patient has obstructive pyelonephritis progressing to septic shock, indicated by hypotension, tachycardia, fever, leukocytosis, and an obstructing ureteral stone.
Recognizing life-threatening sepsis dictates the immediate need for medical stabilization before any surgical intervention is attempted.
2
Determine the requirement for urgent surgical source control.
Following initial medical stabilization, the infected urine must be drained via a percutaneous nephrostomy tube or a double-J ureteral stent.
An obstructed, infected kidney represents a closed-space infection (pus under pressure); without drainage, sepsis will rapidly progress despite antibiotic therapy.
3
Establish the correct timing for definitive stone management and secondary prevention.
Ureteroscopy with lithotripsy is delayed until the patient is completely infection-free. The metabolic evaluation is delayed even further into the outpatient recovery period.
Manipulating a stone during active infection risks systemic dissemination of bacteria. Furthermore, metabolic testing during acute illness yields inaccurate results.

Key Concept

Sequential management of obstructive pyelonephritis and urosepsis
Question 3635Question →

An ambulance brings a 48-year-old female to the emergency department following a sudden collapse at a grocery store. Bystanders report she grabbed her head and screamed about a sudden, explosive headache before briefly losing consciousness. In the ED, her blood pressure is 165/90 mm Hg and heart rate is 88/min. She is groggy, heavily photophobic, and strongly resists neck flexion. Neurologic examination reveals no focal motor or sensory deficits. Arrange the following diagnostic and therapeutic steps in the correct chronological sequence for the standard clinical management of this patient's suspected condition.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence is: 1) Non-contrast CT scan of the head, 2) Cerebral angiogram, 3) Secure the ruptured aneurysm, 4) Initiate daily TCD ultrasonography, and 5) Administer vasopressors for new focal deficits.
The standard of care for aneurysmal subarachnoid hemorrhage (aSAH) follows a strict physiological logic. First, the presence of blood must be proven (Non-contrast CT). Second, the source of the hemorrhage must be localized (Cerebral Angiography). Third, the risk of early, fatal rebleeding must be eliminated by securing the vascular defect (Coiling or Clipping). Fourth, once secured, the patient is monitored for the most common delayed complication, cerebral vasospasm, which typically peaks between days 3 and 14 (TCD Surveillance). Finally, if vasospasm causes delayed cerebral ischemia (DCI), the definitive medical treatment is to drive up systemic blood pressure to perfuse the ischemic penumbra (Induced hypertension). Inducing hypertension is strictly contraindicated until step 3 is complete.

Step-by-Step Solution

1
Diagnose the hemorrhage using a non-contrast CT of the head.
Confirmation of acute subarachnoid blood in the basal cisterns.
It is the fastest and most sensitive initial test for detecting acute subarachnoid hemorrhage (SAH).
2
Visualize the cerebral vasculature using angiography (CTA or DSA).
Identification of the ruptured aneurysm's precise location and morphology.
Detailed vascular mapping is required to plan the definitive intervention (endovascular coiling vs. open surgical clipping).
3
Secure the ruptured aneurysm.
Exclusion of the aneurysm from the cerebral arterial circulation.
Rebleeding is the most common cause of early mortality in aSAH; the aneurysm must be secured immediately to safely allow subsequent physiological management.
4
Monitor for vasospasm using daily transcranial Doppler (TCD).
Early detection of pathologically increased cerebral blood flow velocities.
Following treatment, patients enter a high-risk window for vasospasm (typically days 3 to 14); TCD provides standard non-invasive surveillance.
5
Treat delayed cerebral ischemia (DCI) with induced hypertension.
Improved cerebral perfusion through collateral circulation to ischemic brain tissue.
If symptomatic vasospasm occurs despite standard prophylaxis, vasopressors are used to drive cerebral perfusion, a step that is only safe after the aneurysm is physically secured.

Key Concept

Chronological evaluation and management sequence for aneurysmal Subarachnoid Hemorrhage (aSAH)
Question 3636Question →

A population health researcher is analyzing the long-term respiratory effects of chronic silica dust exposure among mining personnel. A registry of 3,0003,000 miners is reviewed over a 1515-year period. The data show that out of 1,0001,000 miners who were routinely exposed to high levels of silica dust, 200200 developed pulmonary fibrosis. Among the 2,0002,000 miners who worked in administrative roles without silica exposure, 100100 developed pulmonary fibrosis. Based on this cohort data, what is the relative risk of developing pulmonary fibrosis for those exposed to silica dust compared to those who were not exposed?

Show answer & explanation

Answer: 4.04.0

Answer

The relative risk is 4.04.0.
Relative risk (RR) is calculated by dividing the incidence of the disease in the exposed group by the incidence in the unexposed group. In this scenario, the incidence of pulmonary fibrosis in the exposed group is 200/1,000=0.20200 / 1,000 = 0.20. The incidence in the unexposed group is 100/2,000=0.05100 / 2,000 = 0.05. Therefore, the relative risk is 0.20/0.05=4.00.20 / 0.05 = 4.0. This means that miners exposed to silica dust are 44 times more likely to develop pulmonary fibrosis compared to those who are not exposed.

Step-by-Step Solution

1
Calculate the incidence of the disease in the exposed group.
200/1,000=0.20200 / 1,000 = 0.20 (or 20%20\%).
Relative risk requires comparing the absolute risk (incidence) in both the exposed and unexposed populations.
2
Calculate the incidence of the disease in the unexposed group.
100/2,000=0.05100 / 2,000 = 0.05 (or 5%5\%).
This establishes the baseline risk in the population without the exposure.
3
Divide the incidence in the exposed group by the incidence in the unexposed group.
0.20/0.05=4.00.20 / 0.05 = 4.0.
Relative Risk (RR) is the ratio of these two incidences, indicating how many times more likely the exposed group is to develop the disease.

Key Concept

Relative Risk (RR) calculation in a cohort study
Question 3637Question →

An ill-appearing 58-year-old man is evaluated in the emergency department for severe perineal pain, chills, and an inability to pass urine for the past 12 hours. His temperature is 39.2°C (102.6°F), blood pressure is 105/65 mmHg, and heart rate is 112/min. Digital rectal examination demonstrates an exquisitely tender, warm, and swollen prostate gland. A bedside bladder scan reveals 700 mL of retained urine. Arrange the following interventions in the most appropriate chronological sequence for the management of this patient, progressing from immediate medical steps to procedural intervention and definitive surgical management of potential complications.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence is to first obtain microbiological cultures, then administer empiric intravenous antibiotics, followed by a suprapubic cystostomy for safe bladder decompression, and finally surgical drainage if an abscess forms and fails to respond to medical therapy.
The precise chronological management of acute bacterial prostatitis complicated by acute urinary retention demands immediate culture acquisition prior to antibiotics. This is followed by safe bladder decompression using a suprapubic cystostomy to avoid traversing the inflamed prostate, with surgical drainage reserved strictly as a final step for refractory abscesses.

Step-by-Step Solution

1
Obtain blood and urine cultures
Baseline microbiological data is secured before it can be altered by medications.
Crucial for antibiotic stewardship to allow de-escalation of broad-spectrum antibiotics once sensitivities are known.
2
Administer empiric intravenous antibiotics
Systemic treatment for acute bacterial prostatitis is initiated.
The patient exhibits signs of systemic inflammatory response syndrome (fever, tachycardia) and requires immediate antimicrobial therapy.
3
Perform percutaneous suprapubic cystostomy
The bladder is decompressed safely without urethral instrumentation.
Urethral catheterization is contraindicated in acute bacterial prostatitis due to the high risk of inducing septic shock and causing extreme pain.
4
Perform transurethral unroofing and surgical drainage
Infected fluid collections are evacuated from the prostate.
This is a definitive surgical step reserved only for cases that progress to a prostatic abscess unresponsive to conservative management.

Key Concept

In acute bacterial prostatitis with urinary retention, prioritize cultures before antibiotics, decompress the bladder via suprapubic cystostomy to avoid prostatic trauma, and reserve surgical drainage for refractory abscesses.
Estimated Time:1m 30s
Question 3638Question →

A 32-year-old man is brought to the emergency department 45 minutes after being struck on the right side of the head with a heavy wrench during a workplace altercation. Witnesses report he lost consciousness for approximately one minute immediately after the impact, but then awoke and was able to converse normally. Over the past 15 minutes, he has become progressively lethargic and is now unresponsive to verbal commands. His blood pressure is 165/90 mmHg, and his pulse is 52/min. Neurologic examination reveals a dilated, unreactive right pupil and left-sided hemiparesis. A non-contrast CT scan of the head demonstrates a large, biconvex hyperdense mass over the right temporoparietal convexity with a 12-mm leftward midline shift. Which of the following is the most appropriate next step in the management of this patient?

Show answer & explanation

Answer: Urgent surgical craniotomy and hematoma evacuation

Answer

Urgent surgical craniotomy and hematoma evacuation
The correct approach is urgent surgical craniotomy and hematoma evacuation. This patient has a classic presentation of an epidural hematoma, characterized by a traumatic blow to the head, a transient loss of consciousness, a lucid interval, and subsequent rapid neurological deterioration. The CT finding of a biconvex (lens-shaped) hyperdensity confirms the diagnosis. The patient is exhibiting signs of uncal herniation, including a dilated, unreactive ipsilateral pupil (due to compression of the oculomotor nerve) and contralateral hemiparesis (due to compression of the cerebral peduncle). Furthermore, the presence of hypertension and bradycardia (Cushing reflex) indicates critically elevated intracranial pressure. The definitive, life-saving treatment for a symptomatic epidural hematoma with midline shift and herniation is immediate surgical decompression and evacuation of the clot.

Step-by-Step Solution

1
Analyze the patient's history and timeline.
The patient experienced blunt head trauma, a brief loss of consciousness, a 'lucid interval' where he appeared normal, followed by a rapid neurological decline.
This specific sequence of events is the classic clinical presentation of an epidural hematoma.
2
Evaluate the physical examination and vital signs.
The patient exhibits hypertension and bradycardia (Cushing reflex), a blown (dilated and unreactive) right pupil, and left-sided hemiparesis.
These findings indicate significantly elevated intracranial pressure and active right-sided uncal herniation compressing the ipsilateral oculomotor nerve (CN III) and the cerebral peduncle.
3
Interpret the diagnostic imaging.
The non-contrast head CT shows a biconvex (lens-shaped) hyperdense mass with significant midline shift.
A biconvex hemorrhage is pathognomonic for an epidural hematoma, typically caused by the rupture of the middle meningeal artery.
4
Determine the definitive treatment.
The most appropriate next step is urgent surgical craniotomy.
Immediate evacuation of the hematoma is required to relieve the life-threatening intracranial mass effect and reverse the herniation process.

Key Concept

Diagnosis and management of epidural hematoma with uncal herniation
Question 3639Question →

A 45-year-old woman comes to the clinic after noticing a lump in the front of her neck two weeks ago. She has also experienced a 4-kg (8.8-lb) unintentional weight loss, intermittent palpitations, and increased sweating over the past month. Her temperature is 37.0°C (98.6°F), blood pressure is 135/85 mm Hg, and pulse is 108/min. Physical examination shows a 2.5-cm, firm, mobile nodule in the right lobe of the thyroid gland. There is no cervical lymphadenopathy. Laboratory studies show:

TSH: 0.05 mU/L (normal: 0.4-4.0 mU/L)
Free T4: 2.6 ng/dL (normal: 0.8-1.8 ng/dL)

An ultrasound of the neck demonstrates a 2.5-cm solid, hypoechoic nodule in the right thyroid lobe. Which of the following is the most appropriate next step in the management of this patient?

Show answer & explanation

Answer: Radionuclide thyroid scintigraphy

Answer

The most appropriate next step is radionuclide thyroid scintigraphy.
The correct answer is radionuclide thyroid scintigraphy. The initial evaluation of a newly discovered thyroid nodule always includes measurement of serum TSH and a thyroid ultrasound. If the TSH is subnormal (suppressed), it indicates the presence of autonomous thyroid hormone production. The next step is a radionuclide thyroid scan to determine if the nodule is the source of the excess hormone (a 'hot' nodule) or if the rest of the gland is overactive while the nodule is nonfunctioning (a 'cold' nodule). Because hyperfunctioning nodules are almost always benign, FNA is generally not required for hot nodules.

Step-by-Step Solution

1
Analyze the clinical presentation and laboratory results.
The patient has a 2.5-cm thyroid nodule, symptoms of hyperthyroidism, a suppressed TSH (0.05 mU/L), and an elevated Free T4 (2.6 ng/dL).
Establishing the functional status of the thyroid gland is the first step in evaluating a thyroid nodule.
2
Apply the thyroid nodule diagnostic algorithm for a patient with suppressed TSH.
The algorithm dictates that if TSH is subnormal, a radionuclide thyroid scan (scintigraphy) should be performed next.
A radionuclide scan determines if the nodule is hyperfunctioning ('hot', concentrating the tracer) or nonfunctioning ('cold'). Hot nodules are rarely malignant and do not require FNA, whereas cold nodules require FNA to rule out malignancy.

Key Concept

In the evaluation of a thyroid nodule, a suppressed TSH level indicates the need for radionuclide thyroid scintigraphy to differentiate a hyperfunctioning (hot) nodule from a nonfunctioning (cold) nodule.
Question 3640Question →

A 4141-year-old woman is referred to the endocrine surgery clinic after her primary care physician palpated a swelling in her lower neck. She has no palpitations, heat intolerance, or unexpected weight changes. Vital signs are within normal limits. Physical examination reveals a 3.5-cm3.5\text{-cm}, firm, mobile nodule in the right thyroid lobe. Cervical lymph nodes are not palpable. Laboratory testing shows a thyroid-stimulating hormone (TSH) level of 1.8 mU/L1.8 \text{ mU/L} (normal: 0.4−4.0 mU/L0.4 - 4.0 \text{ mU/L}) and a free thyroxine (T4) level of 1.3 ng/dL1.3 \text{ ng/dL} (normal: 0.9−1.7 ng/dL0.9 - 1.7 \text{ ng/dL}). A neck ultrasound confirms a 3.5-cm3.5\text{-cm} solid, isoechoic nodule in the right lobe with a thin hypoechoic halo. A fine-needle aspiration (FNA) biopsy is performed, and cytology yields a highly cellular specimen composed of follicular cells arranged in microfollicles with scant colloid. No nuclear grooves or pseudoinclusions are identified. Which of the following is the most appropriate next step in management?

Show answer & explanation

Answer: Diagnostic right thyroid lobectomy

Answer

Diagnostic right thyroid lobectomy
The correct answer involves performing a diagnostic right thyroid lobectomy. This patient's FNA biopsy reveals a follicular neoplasm (Bethesda Category IV). The distinction between a benign follicular adenoma and a malignant follicular carcinoma relies entirely on identifying transcapsular or vascular invasion under a microscope. Because FNA only samples free cells and cannot assess tissue architecture or the nodule's capsule, cytology alone is insufficient for a definitive diagnosis. Surgical excision, typically via lobectomy, is required to provide the intact nodule capsule for definitive histopathological evaluation. Lobectomy is preferred over total thyroidectomy as the initial step because 70% to 80% of these lesions prove to be benign, and lobectomy minimizes the risks of bilateral recurrent laryngeal nerve injury and permanent hypoparathyroidism.

Step-by-Step Solution

1
Analyze the Fine-Needle Aspiration (FNA) cytology results.
The cytology demonstrates a highly cellular specimen with microfollicles and scant colloid, lacking nuclear features of papillary carcinoma. This defines a follicular neoplasm (Bethesda Category IV).
Establishing the specific cytologic category dictates the subsequent diagnostic algorithm.
2
Identify the inherent diagnostic limitation of the cytology.
FNA samples individual cells but cannot evaluate the nodule's architecture. It cannot distinguish between a benign follicular adenoma and a malignant follicular carcinoma.
Malignancy in follicular neoplasms is defined exclusively by capsular and/or vascular invasion, which requires examination of the entire intact tumor capsule.
3
Determine the safest and most definitive next step in management.
A diagnostic thyroid lobectomy must be performed to provide the pathologist with the entire nodule and its capsule.
Lobectomy provides definitive histopathologic diagnosis while minimizing the morbidity (e.g., recurrent laryngeal nerve injury, hypoparathyroidism) associated with an upfront total thyroidectomy, given that the majority of these lesions are benign.

Key Concept

Management of indeterminate thyroid nodules (Bethesda IV/Follicular Neoplasm)
PreviousPage 182 / 414Next
All practice questions — USMLE Step 2 CK | Examkin