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Question 3101Question →

A 48-year-old man is evaluated in the primary care clinic after noticing a lump in his lower anterior neck while shaving. He reports a recent onset of increased sweating, frequent bowel movements, and an unintended weight loss of 3 kg (6.6 lbs) over the past two months. Vital signs show a temperature of 37.1°C (98.8°F), blood pressure of 134/86 mm Hg, and heart rate of 104/min. Physical examination reveals a 2.5-cm, firm, mobile, non-tender nodule in the left thyroid lobe. There is no cervical lymphadenopathy. Laboratory testing reveals a serum thyroid-stimulating hormone (TSH) level of 0.05 µU/mL (normal: 0.4–4.0 µU/mL) and a free thyroxine (T4) level of 2.6 ng/dL (normal: 0.8–1.8 ng/dL). A subsequent neck ultrasound confirms a 2.5-cm solid nodule in the left thyroid lobe without any suspicious sonographic features (e.g., no microcalcifications or irregular margins). Which of the following is the most appropriate next step in the diagnostic evaluation of this patient?

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Answer: Radionuclide thyroid scintigraphy

Answer

Radionuclide thyroid scintigraphy
The correct sequence for evaluating a newly discovered thyroid nodule begins with a serum TSH and a thyroid ultrasound. When the TSH is suppressed (as seen in this patient with biochemical and symptomatic hyperthyroidism), the most appropriate next step is radionuclide thyroid scintigraphy. This test determines whether the nodule is hyperfunctioning (a 'hot' nodule, which is almost always benign) or nonfunctioning (a 'cold' nodule). If the scan reveals a 'hot' nodule, fine-needle aspiration is not indicated, and the patient is treated for hyperthyroidism. If the scan shows a 'cold' nodule, fine-needle aspiration is then required to evaluate for malignancy.

Step-by-Step Solution

1
Analyze the clinical presentation and laboratory results.
The patient has a 2.5-cm solid thyroid nodule, symptoms of thyrotoxicosis, a suppressed TSH, and an elevated free T4.
Establishing the initial biochemical status is the first step in the algorithm for evaluating any new thyroid nodule.
2
Apply the diagnostic algorithm for a thyroid nodule with a suppressed TSH.
The guideline-indicated next step is to assess the functional status of the nodule using radionuclide thyroid scintigraphy.
If the TSH is suppressed, it is necessary to determine whether the nodule is hyperfunctioning ('hot') or non-functioning ('cold') because hyperfunctioning nodules carry an extremely low risk of malignancy and generally do not require biopsy.

Key Concept

The initial evaluation of a thyroid nodule depends on the TSH level; a suppressed TSH mandates a radionuclide thyroid scan to differentiate a benign hyperfunctioning nodule from a non-functioning nodule that requires fine-needle aspiration.
Question 3102Question →

A 35-year-old man is brought to the emergency department by emergency medical services due to ongoing generalized shaking of his extremities. The paramedics report that the seizure activity began 20 minutes ago and has been continuous without any periods of responsiveness. His past medical history is significant for a traumatic brain injury two years ago. His blood pressure is 142/88 mmHg, heart rate is 118/min, and oxygen saturation is 95% on a non-rebreather mask. Intravenous access is established, and fingerstick blood glucose is 108 mg/dL (6.0 mmol/L).

Arrange the following pharmacologic interventions in the most appropriate escalating sequence for managing this patient's condition, assuming the seizure activity remains refractory to each preceding step.

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Answer

The correct escalating sequence is intravenous lorazepam (first-line), followed by intravenous fosphenytoin (second-line), then continuous intravenous propofol infusion (third-line), and finally continuous intravenous pentobarbital infusion (fourth-line).
The algorithm for status epilepticus management is highly protocolized to minimize neuronal injury. In the initial phase (5-20 minutes), rapidly acting benzodiazepines such as intravenous lorazepam are required to acutely halt seizure activity. If seizures persist into the second phase (20-40 minutes), long-acting antiseizure medications like intravenous fosphenytoin, valproic acid, or levetiracetam are administered to achieve sustained seizure control. If clinical or electrographic seizures continue despite these interventions (refractory status epilepticus), continuous anesthetic infusions such as propofol or midazolam are indicated. Finally, for super-refractory status epilepticus that does not respond to initial anesthetic infusions, deep barbiturate coma with pentobarbital is utilized as a therapy of last resort.

Step-by-Step Solution

1
Identify the clinical presentation as status epilepticus.
The patient has had continuous generalized seizure activity for 20 minutes without regaining consciousness, necessitating immediate sequential pharmacologic intervention.
Status epilepticus is a neurologic emergency requiring prompt termination of excitotoxicity.
2
Administer first-line emergent therapy.
Intravenous lorazepam is the initial drug of choice.
Benzodiazepines rapidly enter the central nervous system to enhance GABA-A receptor activity and stop the seizure.
3
Progress to second-line urgent therapy for persistent seizures.
Intravenous fosphenytoin is administered next.
Non-benzodiazepine antiseizure medications provide sustained seizure control but take longer to reach therapeutic brain concentrations.
4
Initiate third-line continuous infusions for refractory status epilepticus.
A continuous intravenous propofol infusion is started.
Anesthetic infusions effectively suppress cortical activity when standard agents fail, though they require intubation and hemodynamic monitoring.
5
Escalate to fourth-line therapy if the condition becomes super-refractory.
A continuous intravenous pentobarbital infusion is initiated.
Barbiturate coma is the final pharmacologic step due to high rates of severe hypotension, immunosuppression, and prolonged recovery times.

Key Concept

The protocolized management of status epilepticus progresses sequentially from rapidly acting benzodiazepines (lorazepam) to long-acting antiseizure medications (fosphenytoin), followed by general anesthetic infusions (propofol), and ultimately barbiturate coma (pentobarbital).
Estimated Time:1m 30s
Question 3103Question →

Correlate the following distinct central nervous system imaging findings with their most likely underlying clinical diagnosis.

Click a left item, then click its matching right item

Items

Lentiform, hyperdense extra-axial fluid collection bounded by cranial sutures on non-contrast head computed tomography
Crescentic, hyperdense extra-axial fluid collection extending freely across cranial sutures on non-contrast head computed tomography
Loss of gray-white matter differentiation in the lateral margins of the insular cortex on non-contrast head computed tomography
Homogeneous, intensely enhancing dural-based mass with an adjacent tapering margin of enhancement on T1-weighted magnetic resonance imaging

Matches

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Answer

The accurate clinical correlations are: the lentiform collection bounded by sutures indicates an epidural hematoma; the crescentic collection crossing sutures indicates an acute subdural hematoma; the loss of the insular ribbon indicates an acute ischemic stroke; and the enhancing mass with a dural tail indicates a meningioma.
Each imaging finding corresponds strictly to the underlying pathophysiology and anatomical constraints of the specific diagnosis: arterial blood restricted by sutures (epidural hematoma), venous blood spreading freely (subdural hematoma), cytotoxic edema obscuring gray-white interfaces (ischemic stroke), and neoplastic arachnoid cells causing reactive dural thickening (meningioma).

Step-by-Step Solution

1
Analyze the shape and anatomical boundaries of the extra-axial intracranial hemorrhages.
A lentiform shape restricted by suture lines identifies an epidural hematoma, whereas a crescent shape spreading beyond suture lines identifies a subdural hematoma.
Differentiating these hemorrhages relies on understanding that the dura mater is firmly attached to the skull at the suture lines, restricting epidural space expansion, while the subdural space has no such boundaries.
2
Evaluate the early parenchymal ischemic changes on non-contrast imaging.
Obscuration of the insular cortex identifies an early acute ischemic stroke in the middle cerebral artery territory.
The insular cortex is highly susceptible to early ischemic injury, and the resulting cytotoxic edema eliminates the normal gray-white matter interface.
3
Assess the contrast enhancement pattern of the described intracranial mass.
A uniformly enhancing dural-based lesion with a tapering dural tail points directly to a meningioma.
Meningiomas originate from arachnoid cap cells and classically incite a localized dural reaction clearly visible on contrast-enhanced magnetic resonance imaging.

Key Concept

Radiographic differentiation of classic central nervous system pathologies based on anatomic boundaries, edema patterns, and enhancement characteristics.
Estimated Time:1m 30s
Question 3104Question →

A 2828-year-old primigravida at 3434 weeks gestation presents to the obstetrical triage unit complaining of a severe, unrelenting headache, visual scotomas, and right upper quadrant abdominal pain. Her blood pressure is 175/115175/115 mmHg. Physical examination reveals right upper quadrant tenderness and 3+3+ pitting edema of the lower extremities. Laboratory studies show:

Laboratory TestResult
Hemoglobin8.98.9 g/dL
Platelets42,00042,000/mm3^3
Aspartate aminotransferase (AST)210210 U/L
Alanine aminotransferase (ALT)195195 U/L
Creatinine1.51.5 mg/dL

A peripheral blood smear demonstrates numerous schistocytes. The medical team is formulating a differential diagnosis that includes HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, thrombotic thrombocytopenic purpura (TTP), and disseminated intravascular coagulation (DIC). Which of the following laboratory findings would most definitively indicate the presence of disseminated intravascular coagulation (DIC) rather than uncomplicated HELLP syndrome or thrombotic thrombocytopenic purpura (TTP)?

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Answer: Prolonged prothrombin time and decreased fibrinogen

Answer

Prolonged prothrombin time and decreased fibrinogen
The correct answer identifies that a prolonged prothrombin time (PT) and decreased fibrinogen are the hallmark laboratory findings of disseminated intravascular coagulation (DIC). DIC is a consumptive coagulopathy characterized by widespread activation of the clotting cascade, which depletes coagulation factors (resulting in prolonged PT and aPTT) and fibrinogen. In contrast, HELLP syndrome and thrombotic thrombocytopenic purpura (TTP) are primarily characterized by platelet consumption and microangiopathic hemolytic anemia, but they do not typically cause widespread consumption of coagulation factors. Therefore, PT, aPTT, and fibrinogen levels remain normal in uncomplicated HELLP and TTP. The presence of prolonged coagulation times and hypofibrinogenemia in this patient definitively points towards DIC.

Step-by-Step Solution

1
Analyze the clinical presentation and initial laboratory data
The pregnant patient presents with severe hypertension, hepatic injury, and microangiopathic hemolytic anemia (MAHA).
This triad strongly suggests HELLP syndrome, but the differential diagnosis for MAHA must also include TTP and DIC.
2
Identify the pathophysiological differences between the conditions in the differential
HELLP and TTP primarily cause platelet aggregation and microthrombi without systemic consumption of clotting factors. DIC involves widespread activation of the coagulation cascade.
Understanding the underlying mechanisms allows for the selection of the correct laboratory test to differentiate the conditions.
3
Determine the expected laboratory profile for DIC
Because DIC consumes coagulation factors and fibrinogen, it results in a prolonged PT, prolonged aPTT, and decreased fibrinogen.
Identifying this specific profile is required to definitively favor a diagnosis of DIC over uncomplicated HELLP or TTP, which typically feature normal PT, aPTT, and fibrinogen levels.

Key Concept

Formulating a differential diagnosis for microangiopathic hemolytic anemia requires distinguishing conditions based on their coagulation profiles; Disseminated Intravascular Coagulation (DIC) is characterized by prolonged coagulation times (PT/aPTT) and decreased fibrinogen, whereas HELLP syndrome and TTP typically feature normal coagulation parameters.
Question 3105Question →

A 45-year-old woman is evaluated in the clinic for follow-up of difficult-to-control hypertension. Her blood pressure today is 168/102 mmHg despite documented adherence to maximal doses of amlodipine, lisinopril, and hydrochlorothiazide. She reports occasional muscle weakness but is otherwise asymptomatic. Fundoscopy shows no papilledema, and her neurological examination is normal. Laboratory studies reveal a serum potassium of 3.1 mEq/L and a serum sodium of 142 mEq/L. The physician suspects a specific secondary cause of her hypertension. Arrange the following diagnostic steps in the correct sequential order from initial screening to definitive pre-surgical evaluation.

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Answer

The correct diagnostic sequence is: 1) Measurement of plasma aldosterone concentration and plasma renin activity, 2) Intravenous saline infusion test, 3) Computed tomography (CT) scan of the adrenal glands, and 4) Adrenal venous sampling.
The patient's presentation of resistant hypertension and hypokalemia is classic for primary hyperaldosteronism. Because she is clinically stable without target-organ emergency, an elective, tiered diagnostic workup is indicated to avoid unnecessary invasive testing. First, screening is performed with the aldosterone-to-renin ratio. If elevated, the diagnosis is biochemically confirmed using a suppression test like the intravenous saline infusion test, because the screening ratio can yield false positives. Once confirmed, a CT of the adrenal glands is obtained to localize the lesion and rule out large carcinomas. Finally, because non-functioning adrenal incidentalomas are common, adrenal venous sampling is required in most patients to definitively prove that the radiologically identified nodule is hypersecreting aldosterone before committing the patient to a unilateral adrenalectomy.

Step-by-Step Solution

1
Identify the most likely diagnosis based on the clinical presentation.
The patient's resistant hypertension and spontaneous hypokalemia without signs of hypertensive emergency suggest primary hyperaldosteronism.
Establishing the correct pre-test probability dictates the specific diagnostic pathway rather than initiating emergency stabilization.
2
Select the appropriate initial screening test.
Measurement of the plasma aldosterone concentration to plasma renin activity (PAC/PRA) ratio is the first step.
The PAC/PRA ratio has high sensitivity and is the guideline-recommended initial screening method.
3
Determine the necessary confirmatory test.
An intravenous saline infusion test (or oral sodium loading) follows a positive screening ratio.
Screening tests can yield false positives; autonomous aldosterone secretion must be confirmed via a suppression test.
4
Sequence the localization and surgical planning tests.
An adrenal CT scan is followed by adrenal venous sampling.
Imaging localizes the glands and rules out large carcinomas, while venous sampling functionally proves unilateral hypersecretion before committing to surgery.

Key Concept

The diagnostic algorithm for primary hyperaldosteronism progresses stepwise from biochemical screening (PAC/PRA ratio), to biochemical confirmation (suppression testing), to non-invasive anatomical localization (CT scan), and finally to invasive lateralization (adrenal venous sampling) if surgery is planned.
Question 3106Question →

A 54-year-old woman is evaluated in the clinic following a recent emergency department visit for right-sided flank pain. During her acute presentation, a noncontrast computed tomography (CT) scan of the abdomen and pelvis confirmed a 3-mm right ureteral calculus, which she has since passed spontaneously. However, the radiologist's report notes an incidental 3.5-cm solid, well-circumscribed mass in the left adrenal gland. The mass is homogeneous and has an attenuation value of 5 Hounsfield units (HU). The patient has no significant past medical history and takes no medications. She feels well and reports no headaches, palpitations, weakness, or diaphoresis. Her blood pressure is 120/78 mm Hg, and her pulse is 72/min. Physical examination is unremarkable.

Based on the interpretation of the imaging results, which of the following best describes the nature of this finding and the most appropriate next step in management?

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Answer: Benign lipid-rich adenoma; proceed with biochemical testing for hormone hypersecretion

Answer

The correct response identifies the mass as a benign lipid-rich adenoma and correctly recommends proceeding with biochemical testing for hormone hypersecretion.
The correct answer accurately interprets the imaging findings and identifies the standard-of-care next step. On a noncontrast CT scan, an attenuation value of less than 10 Hounsfield units (HU) is diagnostic of a benign, lipid-rich adrenal adenoma. Because the imaging phenotype definitively establishes the anatomic diagnosis as benign, no further imaging characterization (e.g., contrast CT, MRI) or biopsy is indicated. However, structural imaging cannot determine the functional status of the mass. Current guidelines mandate that all adrenal incidentalomas larger than 1 cm undergo biochemical evaluation to rule out subclinical hormone hypersecretion (such as subclinical Cushing syndrome and pheochromocytoma), regardless of the presence or absence of clinical symptoms. Therefore, proceeding with functional biochemical testing is the most appropriate next step.

Step-by-Step Solution

1
Interpret the specific imaging characteristics of the incidental adrenal mass provided in the vignette.
The mass is 3.5 cm, homogeneous, and has an attenuation of 5 Hounsfield units (HU) on a noncontrast CT scan.
Accurate interpretation of Hounsfield units is required to determine the malignant potential of adrenal incidentalomas.
2
Correlate the attenuation value with the differential diagnosis of adrenal masses.
An attenuation value of <10 HU is highly specific for a lipid-rich adrenal adenoma, which is benign and does not require further anatomic imaging.
Recognizing benign imaging phenotypes prevents the overutilization of unnecessary advanced imaging modalities.
3
Determine the required management sequence for a newly discovered, benign-appearing adrenal mass.
Biochemical testing (e.g., 1-mg overnight dexamethasone suppression test and plasma free metanephrines) is required for all incidentalomas >1 cm.
Subclinical hormone hypersecretion can occur in up to 15% of patients with radiographically benign adenomas, dictating the need for functional evaluation.

Key Concept

On noncontrast CT, an adrenal mass with an attenuation of <10 Hounsfield units is diagnostic of a benign lipid-rich adenoma; however, all adrenal incidentalomas >1 cm must still undergo biochemical testing to rule out subclinical hormone hypersecretion.
Question 3107Question →

A 62-year-old woman presents to the preoperative clinic for evaluation ahead of an elective right hemicolectomy scheduled in seven days. The surgery is indicated for a large, flat cecal adenoma that was unamenable to endoscopic resection. Her medical history includes a mechanical mitral valve replacement performed five years ago, type 2 diabetes mellitus, hypertension, and stage 3 chronic kidney disease. She leads an active lifestyle and reports walking at least two miles daily without experiencing chest pain, shortness of breath, or fatigue. Current medications include warfarin, metformin, and lisinopril. Vital signs are within normal limits. Laboratory studies reveal a serum creatinine of 1.5 mg/dL, an INR of 2.8, and an HbA1c of 7.1%. Which of the following procedural and perioperative management steps are indicated for this patient? (Select all that apply)

Select all that apply

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Answer: Stop warfarin five days before surgery and initiate bridging therapy with low-molecular-weight heparin; Withhold the morning dose of lisinopril on the day of the procedure

Answer

The indicated steps are to stop warfarin five days prior to surgery while initiating a low-molecular-weight heparin bridge, and to withhold the morning dose of lisinopril on the day of the procedure.
Appropriate perioperative management requires optimizing safety by balancing surgical bleeding risk with thromboembolic and physiologic risks. For a patient with a mechanical mitral valve (high thromboembolic risk), warfarin must be stopped 5 days prior to surgery to allow the INR to normalize, with a parenteral anticoagulant bridge instituted in the interim. Additionally, ACE inhibitors like lisinopril are generally held the morning of surgery to prevent severe, refractory hypotension during the induction and maintenance of general anesthesia.

Step-by-Step Solution

1
Assess the patient's thromboembolic risk to determine the need for anticoagulation bridging.
The patient has a mechanical mitral valve, placing her in a high-risk category for arterial thromboembolism.
High-risk conditions dictate that the patient cannot be off anticoagulation for a prolonged period, necessitating a bridge with LMWH or unfractionated heparin.
2
Determine the appropriate timeline for warfarin cessation.
Warfarin must be discontinued 5 days before the scheduled surgery.
It takes approximately 5 days for the synthesis of new vitamin K-dependent factors to normalize the INR to a safe level (<1.5) for major abdominal surgery.
3
Evaluate the patient's daily medications for preoperative continuation or cessation.
Lisinopril and metformin should both be withheld on the morning of surgery.
ACE inhibitors can cause severe intraoperative hypotension, and metformin poses a risk of hypoglycemia and lactic acidosis while the patient is fasting.
4
Evaluate the need for preoperative cardiac testing based on functional status.
No further cardiac testing is needed.
The patient is asymptomatic and achieves >4 METs (walking 2 miles daily), meaning she can proceed directly to intermediate-risk surgery without a stress test.

Key Concept

Preoperative management of chronic medications and risk stratification, including anticoagulation bridging for mechanical heart valves and withholding appropriate antihypertensives/hypoglycemics.
Estimated Time:1m 30s
Question 3108Question →

A 58-year-old woman is brought to the emergency department by her family due to progressively worsening shortness of breath, inability to lie flat, and generalized weakness over the past three days. She has a history of ischemic cardiomyopathy with a left ventricular ejection fraction of 25%. Her home medications include sacubitril-valsartan, carvedilol, spironolactone, and dapagliflozin. Temperature is 36.8°C (98.2°F), blood pressure is 86/56 mmHg, pulse is 112/min, and respiratory rate is 24/min. Oxygen saturation is 88% on room air. The patient appears lethargic. Extremities are cool to the touch with faint peripheral pulses and 2+ pitting edema up to the knees. Jugular venous pulsation is visible at the angle of the mandible while sitting upright. Chest auscultation reveals diffuse bilateral crackles extending to the mid-lung fields. Laboratory studies show:

TestResult
Sodium132 mEq/L
Potassium4.2 mEq/L
Blood urea nitrogen45 mg/dL
Creatinine2.3 mg/dL (baseline 1.0 mg/dL)
Lactate3.8 mmol/L

An electrocardiogram shows sinus tachycardia with a left bundle branch block, unchanged from prior tracings. Which of the following is the most appropriate initial pharmacologic intervention for this patient?

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Answer: Intravenous dobutamine

Answer

The most appropriate initial pharmacologic intervention is an intravenous inotropic agent, such as dobutamine.
This patient is presenting with acute decompensated heart failure (ADHF) characterized by volume overload ('wet') and poor end-organ perfusion ('cold'). Her poor perfusion is evidenced by hypotension, cool extremities, altered mentation, elevated lactate, and acute kidney injury. This hemodynamic profile represents cardiogenic shock. The most appropriate initial intervention is the administration of an intravenous inotropic agent, such as dobutamine. Dobutamine is a beta-1 adrenergic agonist that increases myocardial contractility, thereby increasing cardiac output and restoring perfusion to critical organs. Once hemodynamic stability and adequate perfusion are established, targeted volume removal with diuretics can be safely pursued.

Step-by-Step Solution

1
Assess the patient's perfusion status based on clinical signs and laboratory values.
The patient has cool extremities, lethargy, hypotension, elevated lactate, and acute kidney injury.
These findings indicate poor end-organ perfusion, classifying her as 'cold' (cardiogenic shock).
2
Assess the patient's volume status.
The patient has orthopnea, jugular venous distention, pulmonary crackles, and peripheral edema.
These findings indicate severe volume overload, classifying her as 'wet'.
3
Determine the optimal pharmacologic strategy for 'cold and wet' acute decompensated heart failure.
Initial therapy must focus on improving cardiac output and maintaining blood pressure using inotropic agents.
Without inotropic support, attempting diuresis or vasodilation will further compromise perfusion and worsen the shock state.

Key Concept

Patients with 'cold and wet' acute decompensated heart failure (cardiogenic shock) require prompt initiation of inotropic support (e.g., dobutamine) to improve cardiac output and end-organ perfusion prior to aggressive diuresis.
Estimated Time:1m 30s
Question 3109Question →

A 65-year-old man with a history of type 2 diabetes mellitus and peripheral neuropathy is brought to the emergency department due to rapidly worsening right leg pain, swelling, and fever over the past 12 hours. The patient reports the pain is excruciating and much worse than the visible skin changes would suggest. He is confused and lethargic. Vital signs are temperature 39.4∘C39.4^\circ\text{C} (102.9∘F102.9^\circ\text{F}), blood pressure 82/50 mmHg82/50\text{ mmHg}, heart rate 128/min128/\text{min}, and respiratory rate 24/min24/\text{min}. Physical examination reveals a swollen, tense right lower extremity with poorly demarcated erythema advancing proximally toward the knee. Several violaceous bullae are present on the calf, and palpable crepitus is noted over the anterior tibia. Laboratory results show a leukocyte count of 24,000/mm324,000/\text{mm}^3, serum sodium of 130 mEq/L130\text{ mEq/L}, and serum creatinine of 1.9 mg/dL1.9\text{ mg/dL}. Vigorous intravenous fluid resuscitation is initiated. Which of the following is the most appropriate next step in management?

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Answer: Immediate surgical exploration and debridement

Answer

Immediate surgical exploration and debridement
The correct answer is immediate surgical exploration and debridement. The clinical triad of pain out of proportion to the physical examination, rapidly advancing soft tissue infection with crepitus/bullae, and systemic toxicity (septic shock) is highly characteristic of necrotizing fasciitis. The most critical, life-saving intervention for necrotizing fasciitis is immediate, aggressive surgical debridement of all necrotic tissue. While broad-spectrum intravenous antibiotics and fluid resuscitation are essential adjuncts, they cannot replace surgical source control, and surgery must not be delayed for imaging or other diagnostic testing.

Step-by-Step Solution

1
Analyze the clinical presentation and vital signs.
The patient presents with severe pain out of proportion to exam, crepitus, violaceous bullae, and septic shock (hypotension, tachycardia, altered mental status).
To accurately diagnose the underlying life-threatening condition, which in this case is necrotizing fasciitis.
2
Determine the primary, definitive treatment for this condition.
Immediate surgical source control is identified as mandatory.
Intravenous antibiotics and fluid resuscitation alone cannot penetrate necrotic tissue or halt the rapid fascial spread of the infection; surgical debridement is the definitive life-saving intervention.

Key Concept

Surgical management of necrotizing fasciitis
Estimated Time:1m 15s
Question 3110Question →

A 26-year-old man is brought to the emergency department via ambulance after being ejected from a motorcycle at highway speeds. He was not wearing a helmet. On arrival, the patient is unresponsive with a Glasgow Coma Scale score of 6. He has massive midface crush injuries with active, brisk hemorrhage into the oropharynx. He is making gurgling respiratory sounds with poor chest rise. Vital signs are temperature 36.1∘C36.1^\circ\text{C} (97.0∘F97.0^\circ\text{F}), blood pressure 78/48 mm Hg, heart rate 135/min, and respiratory rate 8/min. Oxygen saturation is 84% on room air. The bilateral radial pulses are weak and thready. An attempt at bag-valve-mask ventilation is unsuccessful due to severe facial deformity and continuous bleeding.

Arrange the following management steps in the most appropriate chronological sequence for this patient's initial stabilization and triage.

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Answer

The correct sequence prioritizes immediate life threats: Perform an emergency surgical cricothyroidotomy (Airway), then initiate rapid transfusion of uncrossmatched blood (Circulation), followed by a FAST examination (Primary survey adjunct), then obtain CT scans (Secondary survey/Diagnostics), and finally consult subspecialties for definitive repair.
The management of severe, multi-system trauma follows the Advanced Trauma Life Support (ATLS) protocol, which strictly prioritizes interventions based on the most immediate threats to life: Airway, Breathing, Circulation, Disability, and Exposure (ABCDE). This patient presents with a compromised airway (Glasgow Coma Scale score of 6, gurgling respirations) and massive facial trauma that precludes bag-valve-mask ventilation or standard orotracheal intubation, making a surgical cricothyroidotomy the mandatory first step. Once the airway is secured and ventilation is ensured, attention turns to circulation. The patient is in class III/IV hemorrhagic shock (blood pressure 78/48 mm Hg, heart rate 135/min), necessitating immediate resuscitation with uncrossmatched blood products. Following these life-saving interventions, the primary survey is completed with adjuncts like the FAST exam to rapidly identify major sources of internal bleeding. Only after the patient is hemodynamically stable and the primary survey is complete should the patient be transported to radiology for definitive cross-sectional imaging (CT scans). Finally, with a stabilized patient and complete diagnostic information, appropriate surgical subspecialists can be consulted for definitive operative repair.

Step-by-Step Solution

1
Secure the airway
Perform an emergency surgical cricothyroidotomy
The patient has impending airway loss with an inability to oxygenate or ventilate via standard methods due to massive facial trauma and hemorrhage.
2
Restore intravascular volume
Initiate rapid transfusion of uncrossmatched type O-negative blood
The patient is in profound hemorrhagic shock (hypotension, tachycardia) and requires immediate circulatory support to prevent cardiovascular collapse.
3
Identify concealed sources of hemorrhage
Perform a Focused Assessment with Sonography in Trauma (FAST) examination
A rapid bedside ultrasound helps locate internal bleeding that may require emergent surgical control, completing the primary survey adjuncts.
4
Define exact anatomic injuries
Obtain computed tomography (CT) scans of the head, cervical spine, and torso
Once the patient is stabilized, advanced imaging safely identifies the exact extent of traumatic injuries to guide definitive management.
5
Plan definitive care
Consult oromaxillofacial and neurosurgery teams for definitive operative repair
With the patient stabilized and injuries mapped via imaging, specialized surgical teams are consulted for final structural and neurologic repairs.

Key Concept

Advanced Trauma Life Support (ATLS) Primary Survey Sequence
Estimated Time:1m 30s
Question 3111Question →

A 58-year-old man is brought to the emergency department by his husband due to increasing confusion and lethargy over the past 24 hours. For the last 5 days, he has experienced high, spiking fevers, severe myalgias, and a frontal headache. He has a history of hypertension and hyperlipidemia. He lives in coastal Massachusetts and spent the previous weekend clearing heavy brush in a densely wooded area behind his property.

Temperature is 39.2°C (102.6°F), blood pressure is 105/65 mm Hg, heart rate is 112/min, and respirations are 20/min. Physical examination reveals scleral icterus and a palpably enlarged, tender spleen. There is no rash, eschar, or joint swelling.

Laboratory studies show:

TestResult
Hemoglobin8.8 g/dL (baseline 14.2 g/dL)
Platelets75,000/mm³
Leukocytes4,200/mm³
Total bilirubin4.1 mg/dL
Direct bilirubin0.8 mg/dL
Lactate dehydrogenase720 U/L
Aspartate aminotransferase85 U/L
Alanine aminotransferase72 U/L

The initial triage provider suspects human granulocytic anaplasmosis based on the leukopenia and thrombocytopenia, and recommends starting empiric doxycycline. However, the attending physician notes specific hematologic abnormalities that must alter the primary differential diagnosis. Which of the following conditions is the most likely cause of this patient's presentation?

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Answer: Babesiosis

Answer

The correct answer is Babesiosis, as indicated by the triad of tick exposure in an endemic area, severe febrile illness, and laboratory evidence of profound intravascular hemolytic anemia.
The clinical picture of fever, fatigue, splenomegaly, and a classic hemolytic laboratory profile (anemia, elevated LDH, indirect hyperbilirubinemia) in a patient with recent brush exposure in the Northeastern United States points directly to Babesiosis. Babesia microti is an intraerythrocytic parasite transmitted by the Ixodes scapularis tick. Because it actively replicates within and lyses red blood cells, it produces a hallmark intravascular hemolytic anemia that distinguishes it from other tick-borne infections endemic to the same region. Correctly formulating the differential diagnosis here requires recognizing that suspected anaplasmosis cannot explain the severe hemolysis, necessitating a pivot to Babesiosis. This distinction is critical because the treatment for Babesiosis is atovaquone and azithromycin (or clindamycin and quinine for severe disease), whereas most other tick-borne illnesses are treated with doxycycline.

Step-by-Step Solution

1
Analyze the epidemiologic and clinical risk factors.
The patient has a severe febrile illness with myalgias, confusion, and splenomegaly after clearing brush in Massachusetts, strongly suggesting a tick-borne illness transmitted by the Ixodes scapularis tick.
Establishing the epidemiologic context narrows the broad differential of fever of unknown origin to a specific geographic and vector-borne subset.
2
Interpret the specific pattern of laboratory abnormalities.
The labs show a significant drop in hemoglobin, thrombocytopenia, an elevated total bilirubin that is mostly indirect (unconjugated), and a markedly elevated LDH.
This specific combination confirms an active intravascular hemolytic anemia, which is the key discriminating factor among the differential diagnoses.
3
Differentiate between suspected tick-borne pathogens based on the hemolytic profile.
While Anaplasmosis explains the leukopenia and thrombocytopenia, it does not cause hemolytic anemia. Babesiosis is caused by an intraerythrocytic parasite (Babesia microti) that destroys red blood cells, perfectly accounting for both the systemic symptoms and the hemolytic profile.
Formulating an accurate differential requires rejecting diagnoses that cannot explain objective, severe laboratory derangements.

Key Concept

When formulating a differential diagnosis for tick-borne illnesses in the Northeastern United States, the presence of significant hemolytic anemia (indirect hyperbilirubinemia, elevated LDH, dropping hemoglobin) and splenomegaly should pivot the primary diagnosis away from Anaplasmosis/Lyme disease and toward Babesiosis.
Question 3112Question →

A 48-year-old man is brought to the emergency department by emergency medical services after being found wandering near a bus station. He is agitated, diaphoretic, and yelling at unseen individuals. He has a known history of severe alcohol use disorder and has been hospitalized multiple times for intoxication. Vital signs show a heart rate of 122/min, blood pressure of 168/100 mm Hg, respiratory rate of 20/min, and oxygen saturation of 97% on room air. Fingerstick blood glucose is 82 mg/dL. Physical examination reveals coarse, bilateral hand tremors, bilateral horizontal nystagmus, and a broad-based, unsteady gait. He is disoriented to place and time. Which of the following pharmacologic interventions are appropriate in the immediate management of this patient? (Select all that apply)

Select all that apply

Show answer & explanation

Answer: Intravenous lorazepam; Intravenous thiamine

Answer

The correct interventions are intravenous lorazepam and intravenous thiamine.
The correct choices are intravenous lorazepam and intravenous thiamine. This patient presents with moderate-to-severe alcohol withdrawal, evidenced by autonomic hyperactivity (tachycardia, hypertension, diaphoresis), coarse tremors, and severe agitation. Benzodiazepines, such as lorazepam, are the first-line standard of care for alcohol withdrawal; they enhance GABA-A receptor activity, providing cross-tolerance to alcohol, which controls agitation and significantly reduces the risk of withdrawal seizures and delirium tremens. Furthermore, the patient exhibits the classic triad of Wernicke encephalopathy: encephalopathy (disorientation and agitation), oculomotor dysfunction (horizontal nystagmus), and gait ataxia. This condition is caused by severe thiamine (vitamin B1) deficiency, which is highly prevalent in severe alcohol use disorder. Intravenous thiamine must be administered immediately to reverse these symptoms and prevent the development of irreversible Korsakoff syndrome.

Step-by-Step Solution

1
Identify the patient's primary clinical syndrome based on history and physical exam findings.
The patient is exhibiting signs of acute alcohol withdrawal (tachycardia, hypertension, diaphoresis, tremors, agitation) and Wernicke encephalopathy (nystagmus, ataxia, altered mental status).
Accurate diagnosis of multiple overlapping syndromes dictates the immediate choice of pharmacotherapy and prevents the administration of contraindicated agents.
2
Select the appropriate initial pharmacologic therapy for alcohol withdrawal.
Intravenous lorazepam is chosen to control agitation, stabilize vital signs, and prevent withdrawal seizures.
Benzodiazepines provide essential cross-tolerance at the GABA-A receptor, safely mitigating the effects of abrupt alcohol cessation.
3
Select the appropriate targeted therapy for the patient's acute neurologic deficits.
Intravenous thiamine is selected to treat the triad of nystagmus, ataxia, and encephalopathy.
Chronic alcohol use leads to thiamine deficiency; prompt replenishment is required to reverse Wernicke encephalopathy and prevent irreversible Korsakoff syndrome.

Key Concept

The initial management of a patient presenting with simultaneous alcohol withdrawal and Wernicke encephalopathy requires prompt administration of benzodiazepines to prevent seizures and delirium tremens, alongside intravenous thiamine to prevent permanent neurologic damage.
Question 3113Question →

An unresponsive 68-year-old man with a known history of severe chronic obstructive pulmonary disease is rushed to the resuscitation bay by his family. His wife reports that his breathing became progressively more labored over the previous 6 hours before he became unarousable at home. Currently, the patient only groans and minimally withdraws in response to a sternal rub. His temperature is 37.2°C (99.0°F), blood pressure is 145/88 mmHg, pulse is 118/min, and respiratory rate is 30/min. Pulse oximetry reveals an oxygen saturation of 81% on room air. The physical examination is notable for shallow, rapid respirations with marked intercostal retractions and poor bilateral air movement. Which of the following is the most appropriate initial step in this patient's management?

Show answer & explanation

Answer: Endotracheal intubation

Answer

Endotracheal intubation
This patient is presenting with a severe exacerbation of chronic obstructive pulmonary disease complicated by acute hypercapnic respiratory failure, as evidenced by his profound hypoxia, tachypnea, use of accessory muscles, and unarousable state (CO2 narcosis). During initial triage and stabilization, airway management is the highest priority. Although non-invasive positive pressure ventilation (such as BiPAP) is the preferred initial ventilatory support for alert patients with this condition, an altered level of consciousness is an absolute contraindication. A patient who cannot protect their airway is at a significantly elevated risk for aspiration and requires immediate definitive airway management with endotracheal intubation.

Step-by-Step Solution

1
Assess the patient's hemodynamic and respiratory stability.
The patient is in acute respiratory failure with severe hypoxia and marked respiratory distress.
Vital signs and physical exam dictate whether the patient needs immediate resuscitation (ABCs) or can proceed to diagnostic workup.
2
Evaluate the patient's neurologic status and ability to protect their airway.
The patient is unarousable and only responds to painful stimuli with groaning.
Mental status determines whether non-invasive ventilatory support is safe or if definitive airway protection is required.
3
Select the appropriate stabilization intervention.
Endotracheal intubation is chosen over non-invasive options.
Altered mental status is an absolute contraindication to non-invasive positive pressure ventilation.

Key Concept

In patients with acute exacerbations of chronic obstructive pulmonary disease, the presence of altered mental status or an inability to protect the airway represents an absolute contraindication to non-invasive positive pressure ventilation, necessitating immediate endotracheal intubation.
Question 3114Question →

A 58-year-old man is evaluated in the intensive care unit for new-onset severe abdominal pain. He was admitted 6 hours ago after presenting with sudden, tearing interscapular pain. At the time of admission, computed tomography angiography revealed a Stanford Type B aortic dissection originating just distal to the left subclavian artery and extending to the aortic bifurcation. He was appropriately managed with intravenous esmolol and nicardipine infusions, which reduced his heart rate to 62/min and blood pressure to 112/68 mmHg, resulting in the resolution of his back pain. Currently, he reports diffuse, constant abdominal pain that is out of proportion to the physical examination findings. The abdomen is soft and non-distended, with no rebound tenderness or guarding. His current blood pressure is 115/70 mmHg, and heart rate is 64/min. Laboratory studies show a serum lactic acid level of 5.2 mmol/L, up from 1.1 mmol/L on admission. Which of the following is the most appropriate next step in management?

Show answer & explanation

Answer: Thoracic endovascular aortic repair

Answer

Thoracic endovascular aortic repair
The correct answer is thoracic endovascular aortic repair (TEVAR). This patient originally presented with an uncomplicated Stanford Type B aortic dissection, for which the standard initial treatment is medical anti-impulse therapy (heart rate and blood pressure control). However, his new-onset abdominal pain out of proportion to examination findings and rising serum lactate indicate the development of acute mesenteric ischemia. In the setting of an aortic dissection, this occurs because the intimal flap propagates and dynamically or statically obstructs the origin of the superior mesenteric artery, causing a malperfusion syndrome. The development of malperfusion (e.g., visceral ischemia, renal failure, spinal cord ischemia, or limb ischemia), rapid aortic expansion, or impending rupture transitions the condition to a 'complicated' Type B dissection. Complicated Type B dissections require urgent procedural intervention. TEVAR is the procedure of choice to cover the primary entry tear, depressurize the false lumen, and re-expand the true lumen, thereby restoring distal blood flow to the ischemic organs.

Step-by-Step Solution

1
Analyze the initial presentation and diagnosis.
The patient has a Stanford Type B aortic dissection (distal to the left subclavian artery), initially uncomplicated and appropriately treated with anti-impulse therapy (beta-blockade and afterload reduction).
Establishing the baseline condition determines the standard treatment pathway, which for uncomplicated Type B dissection is medical management.
2
Evaluate the new clinical findings in the intensive care unit.
The patient developed severe abdominal pain out of proportion to exam and a significantly elevated serum lactate (5.2 mmol/L).
These findings are highly specific for acute mesenteric ischemia.
3
Synthesize the findings to update the diagnosis and management plan.
The mesenteric ischemia is secondary to the dissection flap extending into or covering the origin of the superior mesenteric artery. This transitions the diagnosis to a 'complicated' Type B aortic dissection.
Complicated Type B dissections (characterized by malperfusion syndromes, rapid expansion, or rupture) fail medical management and require urgent procedural intervention.
4
Select the appropriate procedural intervention.
Thoracic endovascular aortic repair (TEVAR) is indicated to cover the primary intimal tear, expand the true lumen, and restore perfusion to the visceral vessels.
TEVAR is the standard of care for restoring distal perfusion in complicated Type B aortic dissections, superseding isolated downstream procedures or continued medical therapy.

Key Concept

Management of complicated Stanford Type B aortic dissection with end-organ malperfusion
Question 3115Question →

Emergency medical services transport a 68-year-old female to the resuscitation bay due to sudden-onset, crushing substernal chest discomfort and severe shortness of breath that awoke her from sleep 45 minutes prior. Her past medical history includes type 2 diabetes mellitus, hypertension, and a 40-pack-year smoking history. Initial vital signs obtained by the triage nursing staff show a temperature of 36.8°C (98.2°F), a heart rate of 122/min, a blood pressure of 78/50 mmHg, and a respiratory rate of 34/min. Pulse oximetry indicates an oxygen saturation of 80% on room air. On physical examination, the patient is diaphoretic, agitated, and communicating only in one-to-two word phrases due to severe respiratory distress. Prominent jugular venous distention is noted. Pulmonary auscultation reveals diffuse, coarse crackles throughout all lung fields bilaterally. Cardiac auscultation reveals a regular tachycardia and an audible S3 gallop, without murmurs. An immediate 12-lead electrocardiogram obtained upon arrival shows 4-mm ST-segment elevations in leads V1 through V6 with reciprocal changes in the inferior leads. Two large-bore intravenous lines are established. Which of the following represents the single most urgent priority in the initial stabilization of this patient?

Show answer & explanation

Answer: Endotracheal intubation and mechanical ventilation

Answer

The most urgent initial step is endotracheal intubation and mechanical ventilation to secure the airway and treat the severe hypoxemia before any transfer or further interventions.
The correct answer addresses the most immediate threat to the patient's life: impending respiratory failure and profound hypoxemia. This patient is experiencing a massive anterior ST-elevation myocardial infarction (STEMI) complicated by cardiogenic shock and severe pulmonary edema (Killip Class IV). Her respiratory rate of 34/min, extreme hypoxemia (80%), agitation, and inability to speak in full sentences strongly suggest she is tiring and will soon lose her airway. According to the principles of initial stabilization and triage, securing the Airway and Breathing (the 'A' and 'B' of primary resuscitation) is the absolute first priority. Endotracheal intubation will correct her hypoxemia, drastically reduce the metabolic work of breathing (which currently consumes a large portion of her low cardiac output), and provide positive pressure ventilation that can decrease left ventricular afterload. Only after her airway and breathing are secured can she be safely managed pharmacologically or transferred for definitive revascularization.

Step-by-Step Solution

1
Assess the primary survey (ABCs) based on the patient's presentation.
The patient has severe hypoxia (80% on room air), extreme tachypnea (34/min), and altered mental status (agitation) indicating impending respiratory failure.
Basic life support and advanced trauma/cardiac life support guidelines mandate that airway and breathing abnormalities be addressed before establishing definitive diagnoses.
2
Evaluate the underlying hemodynamic status.
The patient is in cardiogenic shock (BP 78/50 mmHg) secondary to a massive anterior myocardial infarction, leading to acute cardiogenic pulmonary edema.
Identifying the etiology of shock helps anticipate the pathophysiologic response to interventions. In cardiogenic shock, intubation not only corrects hypoxia but also decreases the metabolic work of breathing and reduces left ventricular afterload.
3
Prioritize interventions based on the urgency of life threats.
Endotracheal intubation is selected as the immediate next step, taking precedence over PCI transfer, oral antiplatelets, or imaging.
An unstable patient cannot safely be transported to the catheterization laboratory or given oral medications without first stabilizing the airway and ensuring adequate oxygenation.

Key Concept

In acute medical emergencies, stabilization of the airway and breathing (ABCs) is the paramount initial priority and must precede definitive diagnostic workup, facility transfer, or condition-specific pharmacotherapy.
Question 3116Question →

A 27-year-old woman presents to the outpatient clinic for a routine health maintenance examination. She has felt well overall but mentions experiencing occasional, dull, throbbing headaches over the past few months. She has no significant past medical history. Her only medication is a combined oral contraceptive pill, which she has taken for three years. She does not use tobacco, alcohol, or illicit drugs. Her family history is notable for a father with type 2 diabetes mellitus; there is no family history of early-onset cardiovascular disease.

Vital signs show a blood pressure of 172/105 mm Hg in the right arm and 168/104 mm Hg in the left arm. Her pulse is 76/min, and respiratory rate is 14/min. Her body mass index is 21 kg/m². On physical examination, the lungs are clear to auscultation, and the heart has a regular rate and rhythm without murmurs. Auscultation of the abdomen reveals a soft, high-pitched, continuous bruit in the right periumbilical region. There is no peripheral edema.

Laboratory studies are notable for:
- Sodium: 141 mEq/L
- Potassium: 3.1 mEq/L
- Chloride: 102 mEq/L
- Bicarbonate: 29 mEq/L
- Blood urea nitrogen: 12 mg/dL
- Creatinine: 0.8 mg/dL

Which of the following is the most likely diagnosis?

Show answer & explanation

Answer: Fibromuscular dysplasia

Answer

The most likely diagnosis is fibromuscular dysplasia.
The correct diagnosis is fibromuscular dysplasia (FMD). This patient presents with severe hypertension, hypokalemia, and a right-sided abdominal bruit. In a young female lacking cardiovascular risk factors, this classic triad strongly suggests renovascular hypertension secondary to FMD. FMD is a nonatherosclerotic, noninflammatory vascular disease that most commonly affects the renal and internal carotid arteries in young to middle-aged women. Decreased perfusion to the affected kidney stimulates the juxtaglomerular cells to release renin. This activates the renin-angiotensin-aldosterone system, leading to secondary hyperaldosteronism, which subsequently manifests as hypertension, hypokalemia, and metabolic alkalosis. The continuous abdominal bruit is a direct physical sign of turbulent flow through the stenosed renal artery.

Step-by-Step Solution

1
Analyze the patient's demographic and vital signs.
The patient is a healthy 27-year-old woman presenting with severe, asymptomatic hypertension (>170/100 mm Hg).
Severe hypertension in a young adult without a significant family history strongly warrants investigation for secondary causes.
2
Correlate physical examination and laboratory findings.
The physical examination reveals an abdominal bruit, and laboratory studies show hypokalemia with metabolic alkalosis.
An abdominal bruit indicates turbulent blood flow, suggesting vascular stenosis. The hypokalemia and metabolic alkalosis reflect secondary hyperaldosteronism, driven by increased renin release due to decreased renal perfusion.
3
Differentiate between the causes of renovascular hypertension.
Given the patient's young age and absence of atherosclerotic risk factors, the non-inflammatory condition fibromuscular dysplasia is the most probable cause.
Atherosclerotic renal artery stenosis is much more common overall but almost exclusively affects older patients with established cardiovascular risk factors.

Key Concept

Secondary hypertension due to fibromuscular dysplasia should be suspected in young women presenting with severe hypertension, an abdominal bruit, and hypokalemia driven by secondary hyperaldosteronism.
Question 3117Question →

Pulmonary embolism (PE) is a potentially life-threatening condition, but its diagnostic workup must be tailored to patient stability, pre-test probability, and comorbidities to avoid unnecessary risk. Match each patient presentation with the most appropriate guideline-indicated next diagnostic step in their evaluation.

Click a left item, then click its matching right item

Items

A 65-year-old man with high clinical probability of PE (Wells score 6.5) and an estimated glomerular filtration rate of 22 mL/min/1.73 m2
A 45-year-old woman with suspected massive PE presenting with a blood pressure of 70/40 mmHg on vasopressors, deemed too hemodynamically unstable for transport
A 32-year-old pregnant woman at 12 weeks gestation presenting with acute-onset dyspnea, pleuritic chest pain, and unilateral right calf swelling
A 28-year-old man with mild pleuritic chest pain, normal vital signs, no signs of deep vein thrombosis, and low clinical probability of PE (Wells score 1.0)

Matches

Show answer & explanation

Answer

The correct pairings align the patient's specific clinical constraints (severe renal failure, hemodynamic instability, pregnancy with DVT signs, and low pre-test probability) with their corresponding safe and effective diagnostic modality.
The correct matches follow guideline-directed diagnostic pathways for pulmonary embolism: D-dimer is used exclusively to rule out PE in low-probability patients; bedside echocardiography evaluates for right heart strain in hemodynamically unstable patients who cannot safely travel; V/Q scanning replaces CTPA in patients with severe renal dysfunction; and lower extremity compression ultrasonography is the first step in pregnant patients presenting with leg symptoms to avoid unnecessary radiation.

Step-by-Step Solution

1
Evaluate the pre-test probability and hemodynamic stability of each patient.
Identified low probability in the 28-year-old, severe hemodynamic instability in the 45-year-old, and high clinical probability in the remaining two patients.
Hemodynamic stability determines if the patient can undergo transport for advanced imaging, while clinical probability dictates if a non-invasive rule-out test is appropriate.
2
Identify specific physiological contraindications to standard computed tomography pulmonary angiography (CTPA).
The 65-year-old has severe renal impairment, and the 32-year-old is pregnant and presenting with concurrent signs of a deep vein thrombosis.
CTPA contrast can precipitate acute kidney injury in advanced chronic kidney disease, and radiation exposure should be minimized in pregnancy if alternative diagnostic pathways (like scanning the symptomatic leg) exist.
3
Match the optimal alternative test to each clinical constraint.
Assigned V/Q scan to the patient with renal failure, bedside echocardiography to the unstable patient, lower extremity ultrasound to the pregnant patient, and D-dimer to the low-probability patient.
These pairings adhere strictly to established clinical guidelines for the workup of pulmonary embolism.

Key Concept

Diagnostic algorithms for suspected pulmonary embolism must be adapted sequentially based on hemodynamic stability, pre-test probability (e.g., Wells criteria), renal function, and pregnancy status.
Question 3118Question →

A 64-year-old man presents to the clinic for an initial visit to establish primary care. He has a history of chronic obstructive pulmonary disease and a 40 pack-year smoking history. Two weeks ago, he was evaluated at an urgent care center for an exacerbation of his chronic cough, which was successfully treated with a short course of oral corticosteroids. A chest radiograph performed during that visit revealed a 14-millimeter, noncalcified, peripheral nodule in the right upper lobe. Medical records indicate that a previous chest radiograph obtained four years ago showed no evidence of this nodule. The patient currently feels well and reports his cough has returned to baseline. Vital signs are within normal limits. Physical examination reveals distant breath sounds and mild end-expiratory wheezing, but is otherwise unremarkable.

Which of the following is the most appropriate next step in the diagnostic evaluation of this patient's lung nodule?

Show answer & explanation

Answer: Computed tomography of the chest

Answer

The most appropriate next step is to perform a computed tomography (CT) of the chest.
The correct sequence for evaluating a newly discovered solitary pulmonary nodule begins with comparing the current radiograph to previous imaging. Since this has already been done and confirms the nodule is new, the immediate next step is to obtain a non-contrast, thin-slice computed tomography (CT) scan of the chest. A CT scan provides critical anatomical details—precise size, margins (e.g., smooth vs. spiculated), and internal density (e.g., benign calcification patterns)—that a plain radiograph cannot reliably demonstrate. These features are strictly required to stratify the patient's risk of malignancy and to guide subsequent management, which might involve a PET scan, tissue sampling, or interval CT surveillance.

Step-by-Step Solution

1
Identify the primary clinical problem from the vignette.
The patient has a newly identified, 14-millimeter solitary pulmonary nodule on a chest radiograph.
Establishing the primary problem directs the application of the correct diagnostic algorithm.
2
Assess the patient's risk factors and the chronicity of the finding.
The patient is high-risk (age >60, 40 pack-year smoking history), and previous imaging confirms the nodule is new within the last four years.
Prior imaging is the first step in evaluating a pulmonary nodule; a stable nodule for >2 years typically requires no further workup, whereas a new nodule requires immediate further characterization.
3
Determine the next sequential diagnostic step according to established guidelines for a new pulmonary nodule.
A thin-slice, non-contrast CT scan of the chest is indicated.
Chest radiography lacks the resolution to accurately assess the size, margins, and internal characteristics (like specific calcification patterns or fat) of a nodule. CT is required to inform the next steps, which may include PET, biopsy, or surveillance.

Key Concept

The initial evaluation of a newly identified solitary pulmonary nodule on a chest radiograph requires comparison with old imaging; if the nodule is new or changing, the mandatory next step in the diagnostic sequence is a dedicated non-contrast chest CT.
Question 3119Question →

A 68-year-old woman is brought to the emergency department by emergency medical services at 07:30 due to sudden neurological deficits. Her husband reports that they went to bed at 22:00 the previous night, at which time she was at her baseline. Upon waking at 07:00, she was found to have dense right-sided weakness and severe difficulty speaking. On examination, her blood pressure is 165/90 mmHg, heart rate is 88/min, and oxygen saturation is 98% on room air. Neurologic examination reveals right-sided hemiplegia, a right facial droop, and expressive aphasia. The clinical team activates the acute stroke protocol for a suspected 'wake-up' ischemic stroke. Arrange the following imaging modalities and confirmatory protocols in the most appropriate sequential order for the diagnostic workup and management of this patient, from first to last.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequential order for evaluating a wake-up stroke is: NCCT of the head, CTA of the head and neck, MRI of the brain with DWI/FLAIR sequences, and finally Endovascular DSA.
The standard imaging sequence for a wake-up stroke prioritizes speed and sequential exclusion of contraindications based on consecutive interpretations. Non-contrast CT is strictly the first step to rule out hemorrhage. CT angiography immediately follows to detect large vessel occlusions. Because the exact time of symptom onset is unknown in a wake-up stroke, tissue viability must be assessed. This is effectively done by interpreting an MRI for a DWI-FLAIR mismatch (presence of acute ischemia on DWI without corresponding hyperintensity on FLAIR), which determines if intravenous thrombolysis is safe and indicated. Finally, if a large vessel occlusion is found and salvageable tissue is present, the patient proceeds to the neurointerventional suite for digital subtraction angiography and mechanical thrombectomy.

Step-by-Step Solution

1
Rule out intracranial hemorrhage
Perform Non-contrast CT of the head.
Hemorrhage is an absolute contraindication to thrombolytic and endovascular therapies; NCCT is the fastest modality for this.
2
Identify potential large vessel occlusion
Perform CT Angiography of the head and neck.
Detects proximal occlusions (e.g., MCA M1 segment) that may benefit from endovascular mechanical thrombectomy.
3
Assess tissue viability and estimate stroke timeline
Perform MRI of the brain with DWI and FLAIR.
A DWI-FLAIR mismatch indicates the stroke likely occurred within the last 4.5 hours, identifying patients who may safely receive thrombolytics despite an unknown onset time.
4
Confirm occlusion and perform intervention
Perform Endovascular Digital Subtraction Angiography.
Provides definitive diagnostic confirmation of the vascular anatomy and allows for simultaneous mechanical thrombectomy.

Key Concept

Step-wise imaging evaluation of wake-up strokes requires sequentially ruling out hemorrhage, identifying large vessel vascular occlusion, determining tissue viability via perfusion or DWI-FLAIR mismatch, and finally performing therapeutic angiography.
Question 3120Question →

A 6565-year-old man presents to the urgent care clinic with a 11-day history of excruciating pain in his right big toe. The pain awoke him from sleep and is so severe that he cannot tolerate the weight of his bedsheets. His medical history is significant for ischemic cardiomyopathy with a left ventricular ejection fraction of 25%25\%, chronic kidney disease stage 4, type 2 diabetes mellitus, and hyperlipidemia. His current medications include carvedilol, sacubitril-valsartan, empagliflozin, furosemide, and atorvastatin. Vital signs show a blood pressure of 118/76118/76 mm Hg, heart rate of 7272/min, and temperature of 37.1∘37.1^\circ C. Physical examination reveals a markedly erythematous, swollen, and exquisitely tender right first metatarsophalangeal joint. The remainder of the joint examination is unremarkable. Laboratory studies from one week ago showed a serum creatinine of 2.62.6 mg/dL (estimated glomerular filtration rate 2424 mL/min/1.731.73 m 2^2) and a hemoglobin A1c of 7.8%7.8\%. Joint aspiration is deferred as the clinical presentation is highly classic for podagra. Which of the following is the most appropriate initial pharmacologic therapy for this patient's acute joint condition?

Show answer & explanation

Answer: Intra-articular methylprednisolone

Answer

Intra-articular methylprednisolone
The correct answer is intra-articular methylprednisolone. This patient has classic acute gouty arthritis (podagra). In a patient with multiple severe comorbidities including heart failure with reduced ejection fraction, stage 4 chronic kidney disease, and diabetes mellitus, systemic therapies pose significant risks. Nonsteroidal anti-inflammatory drugs (NSAIDs) are contraindicated due to heart failure and severe renal impairment. Colchicine is associated with severe neuromyopathy in advanced renal failure, a risk that is amplified by concomitant statin use. Systemic glucocorticoids could worsen both heart failure (through fluid retention) and diabetes (through hyperglycemia). Therefore, an intra-articular glucocorticoid injection provides rapid, effective, localized relief for monoarticular disease while safely circumventing the patient's systemic contraindications.

Step-by-Step Solution

1
Diagnose the acute condition.
The patient is experiencing an acute gout flare (podagra) of the first metatarsophalangeal joint.
The sudden onset of severe nocturnal pain, erythema, and exquisite tenderness at the first MTP joint is the classic presentation of acute gout.
2
Evaluate the patient's comorbidities and current medications.
The patient has HFrEF, Stage 4 CKD, Type 2 Diabetes, and takes a statin.
Comorbidities dictate which standard acute gout treatments (NSAIDs, colchicine, systemic steroids) are safe to use.
3
Eliminate contraindicated or high-risk systemic therapies.
NSAIDs and colchicine are ruled out. Systemic glucocorticoids are less desirable.
NSAIDs worsen CKD and HF. Colchicine causes toxicity in CKD, worsened by statins. Systemic steroids can exacerbate HF (fluid retention) and diabetes (hyperglycemia).
4
Select the safest effective intervention.
Intra-articular methylprednisolone is chosen.
For monoarticular gout, intra-articular glucocorticoids deliver potent anti-inflammatory effects directly to the joint while minimizing systemic absorption and avoiding systemic contraindications.

Key Concept

Management of acute gout flares in patients with multiple medical comorbidities that contraindicate standard systemic therapies.
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