USMLE Step 3
Practice Test 3 for USMLE Step 3: real questions and explanations from the Varsity Tutors practice-test pool.
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A 45-year-old man with moderate-to-severe ulcerative colitis was started on ustekinumab (an IL-12/23 inhibitor) 16 weeks ago after failing anti-TNF therapy. He reports that his symptoms of diarrhea and urgency have improved by about 50%, but he still has 4-5 bowel movements per day with some blood. His C-reactive protein has decreased but remains mildly elevated.
Which of the following is the most appropriate next step to guide further management?
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A 45-year-old man with moderate-to-severe ulcerative colitis was started on ustekinumab (an IL-12/23 inhibitor) 16 weeks ago after failing anti-TNF therapy. He reports that his symptoms of diarrhea and urgency have improved by about 50%, but he still has 4-5 bowel movements per day with some blood. His C-reactive protein has decreased but remains mildly elevated.
Which of the following is the most appropriate next step to guide further management?
Explanation: This patient has had a partial clinical response to ustekinumab. The next step is to objectively assess for endoscopic improvement (mucosal healing), which is a key therapeutic goal in IBD and a better predictor of long-term outcomes than symptoms alone. A flexible sigmoidoscopy is the best way to evaluate this. If there is ongoing inflammation, management changes (e.g., dose optimization) may be considered. Checking drug levels can be useful, but objective assessment of inflammation is paramount. Switching therapy is premature without endoscopic assessment. Adding mesalamine is unlikely to provide significant benefit in a patient with moderate-to-severe disease already on a potent biologic.
A 38-year-old man who underwent a total proctocolectomy with ileal pouch-anal anastomosis (IPAA) for medically refractory ulcerative colitis 3 years ago presents with a 2-month history of increased stool frequency, abdominal cramping, and urgency. He denies fever or bloody stools. He has been well since his surgery.
Which of the following is the most likely diagnosis?
Explanation: Pouchitis, or inflammation of the ileal pouch, is the most common long-term complication after IPAA for ulcerative colitis. The symptoms of increased stool frequency, cramping, and urgency are classic for this condition. While Crohn disease of the pouch can occur, it is less common, especially if the original diagnosis was definitive UC. Irritable pouch syndrome is a diagnosis of exclusion. Small intestinal bacterial overgrowth typically presents with more bloating and flatulence. Given the inflammatory nature of the symptoms, pouchitis is the most probable diagnosis and is typically treated with antibiotics like ciprofloxacin or metronidazole.
A 31-year-old G2P2 who is 6 weeks postpartum after an uncomplicated vaginal delivery asks for advice on family planning. She and her partner would like another child but want to ensure the timing is optimal for the health of both mother and baby. She has no chronic medical conditions.
Explanation: The interpregnancy interval (IPI) is the time from one live birth to the conception of the next pregnancy. Epidemiologic studies have shown that a short IPI (<18 months) is associated with an increased risk of adverse outcomes in the subsequent pregnancy, including preterm birth, low birth weight, and small for gestational age infants, as well as increased maternal risks like anemia. Counseling patients to wait at least 18 months before conceiving again is the standard recommendation to allow for maternal nutritional and physiological recovery. (A, B) Intervals of 6 or 12 months are considered short and are associated with increased risks. (D) While a very long IPI (>59 months) is also associated with some increased risks (e.g., preeclampsia), there is no evidence that waiting beyond 18-24 months provides additional benefit.
A 45-year-old woman is evaluated 3 months after a cryptogenic ischemic stroke. A comprehensive workup for stroke etiology was negative, but a transesophageal echocardiogram with a bubble study confirmed the presence of a patent foramen ovale (PFO) with a large right-to-left shunt. She has no other medical problems.
Which of the following is the most appropriate long-term management strategy for this patient?
Explanation: Multiple randomized controlled trials (e.g., RESPECT, CLOSE) have demonstrated that in patients aged 18-60 with a cryptogenic stroke attributed to a PFO, percutaneous PFO closure combined with antiplatelet therapy is superior to medical therapy (either antiplatelet or anticoagulant) alone in preventing recurrent stroke. Given this patient's age and clinical presentation, PFO closure is the recommended intervention.
A 60-year-old woman with cirrhosis presents for routine surveillance. She has no new symptoms and remains abstinent from alcohol. Labs: bilirubin 1.9 mg/dL, albumin 3.0 g/dL, INR 1.5. Prior ultrasound 6 months ago shows no focal liver lesion. She asks how to monitor for liver cancer. What is the next best step in management for this patient?
Explanation: This question tests the management of chronic liver disease and cirrhosis, focusing on clinical decision-making appropriate for independent practice. Chronic liver disease requires careful monitoring and management of complications such as ascites, hepatic encephalopathy, and variceal bleeding. In this vignette, the patient's cirrhosis and risk for hepatocellular carcinoma suggest need for surveillance, requiring immediate assessment and treatment to prevent complications. The correct choice, ultrasound of the liver every 6 months with or without AFP, reflects the appropriate initial management step, aligning with current guidelines for managing cirrhosis and its complications. A common distractor choice, no surveillance is needed after hepatitis C cure, fails because it suggests a non-standard treatment, highlighting a common misconception about liver disease management. To aid learning, emphasize the importance of lifestyle modifications and regular monitoring of liver function to manage and prevent progression of cirrhosis. Encourage the practice of applying standardized guidelines to diverse clinical scenarios.
A 45-year-old patient undergoes a laparoscopic appendectomy. During the procedure, the surgeon inadvertently causes a thermal injury to a small section of the adjacent cecum. The injury is not recognized at the time of surgery. Three days later, the patient develops peritonitis from a delayed bowel perforation, requiring an emergency laparotomy and bowel resection. This entire sequence of events is best classified as which of the following?
Explanation: A sentinel event is a patient safety event that results in death, permanent harm, or severe temporary harm. An unrecognized intraoperative injury leading to a second major surgery and peritonitis meets this definition. A near miss (A) is an error that is caught before it reaches the patient or causes harm. While some complications are unpreventable (C), an unrecognized iatrogenic injury is generally considered a preventable error. Malpractice (D) is a legal determination, not a patient safety classification, and punitive damages are a specific legal finding beyond the scope of this classification.
A 67-year-old woman is transferred from the ICU after treatment for a pulmonary embolism (PE). She was started on an intravenous heparin infusion. She is now hemodynamically stable and her oxygen requirement has decreased. The ICU team planned to transition her to an oral anticoagulant. Her medical history is significant for stage 4 chronic kidney disease (eGFR 25 mL/min/1.73m²).
Which of the following is the most appropriate choice for her oral anticoagulation?
Explanation: The management of PE in patients with severe chronic kidney disease (eGFR < 30 mL/min/1.73m²) is complex, as most direct oral anticoagulants (DOACs) are renally cleared and have limited data or are contraindicated in this population. Warfarin is the most appropriate and safest choice for this patient, as its metabolism is not dependent on renal function. Dabigatran is contraindicated with a CrCl < 30. Rivaroxaban is also contraindicated with a CrCl < 30 for PE treatment. While apixaban can be used with caution in some patients with CKD, warfarin remains the preferred agent in severe renal impairment, especially in the context of a life-threatening PE.
A 48-year-old woman is seen for a 1-year follow-up visit after undergoing a Roux-en-Y gastric bypass for morbid obesity. She has lost 100 pounds and her type 2 diabetes is in remission. She takes a daily multivitamin, calcium citrate, and vitamin D. She reports some mild fatigue but is otherwise well.
In addition to a complete blood count, which of the following sets of laboratory tests is most important to obtain as part of her routine annual nutritional screening?
Explanation: Roux-en-Y gastric bypass surgery bypasses the duodenum and proximal jejunum, which are primary sites for the absorption of iron, folate, and vitamin B12. Therefore, patients are at high risk for these deficiencies, which can cause anemia and fatigue. Guidelines recommend annual screening for these micronutrients, along with others like thiamine and vitamin D, following this procedure.
A 28-year-old G1P1 woman comes to the clinic 8 weeks after an uncomplicated vaginal delivery. She reports feeling overwhelmed, cries frequently, and has lost interest in activities she used to enjoy. She expresses feelings of guilt about not being a "good enough" mother and has difficulty sleeping even when the baby is asleep. Her Edinburgh Postnatal Depression Scale (EPDS) score is 15. What is the most appropriate initial step in management?
Explanation: The patient's symptoms (anhedonia, guilt, sleep disturbance) lasting for several weeks, along with an EPDS score >10, are diagnostic of postpartum depression, not postpartum blues which are transient and milder. First-line treatment for moderate to severe postpartum depression is a combination of psychotherapy and pharmacotherapy, typically with an SSRI. Many SSRIs are safe in lactation. Hospitalization is reserved for patients with suicidal ideation, homicidal ideation, or psychosis.
A 9-year-old boy with Duchenne muscular dystrophy (DMD) has been on daily corticosteroid therapy for the past 3 years to preserve ambulation. He presents for a routine follow-up. His physical examination is stable. His parents are concerned about the long-term effects of his medication.
Which of the following represents the most significant adverse effect of chronic steroid use in this patient population, requiring diligent surveillance and management?
Explanation: When evaluating chronic corticosteroid side effects in pediatric patients with neuromuscular conditions like DMD, you need to consider both frequency and clinical severity. While steroids provide crucial functional benefits by slowing muscle deterioration, their long-term use creates significant management challenges. Bone demineralization and vertebral fractures (D) represent the most serious complication requiring intensive monitoring. Children with DMD already have reduced mobility, which decreases bone loading and contributes to osteoporosis. Chronic steroids dramatically accelerate this process by inhibiting osteoblast function and increasing bone resorption. The combination creates a perfect storm for pathological fractures, particularly vertebral compression fractures that can cause pain, deformity, and further functional decline. These complications require regular bone density monitoring, calcium/vitamin D supplementation, and sometimes bisphosphonate therapy. Weight gain and cushingoid features (A) are extremely common and cosmetically concerning but rarely life-threatening. Behavioral changes and irritability (B) are frequent early side effects that often improve with dose adjustments or alternative steroid regimens. Posterior subcapsular cataracts (C) do occur with chronic steroid use but develop slowly and can be surgically corrected when vision is significantly impaired. The key distinction is that while options A, B, and C represent manageable or reversible complications, vertebral fractures can cause permanent disability and pain in patients who already face progressive muscle weakness. Study tip: For USMLE Step 3, prioritize complications that cause irreversible harm or significantly impact quality of life when ranking adverse effects in chronic disease management scenarios.
A randomized controlled trial was conducted to evaluate the efficacy of a novel antiplatelet agent, Drug Y, compared to clopidogrel for secondary prevention in patients with a recent non-cardioembolic ischemic stroke. The primary outcome was recurrent ischemic stroke at 1 year. Recurrent stroke occurred in 5.2% of the Drug Y group and 7.5% of the clopidogrel group (Hazard Ratio [HR] 0.69; 95% Confidence Interval [CI] 0.55-0.87; P=0.002). Major bleeding occurred in 3.1% of the Drug Y group and 1.6% of the clopidogrel group (HR 1.94; 95% CI 1.35-2.78; P<0.001).
Based on these results, which of the following is the most accurate conclusion?
Explanation: The results show that Drug Y reduced the risk of the primary outcome (recurrent stroke) by 31% compared to clopidogrel (HR 0.69). Since the 95% CI (0.55-0.87) does not cross 1.0 and the P value is <0.05, this result is statistically significant. For major bleeding, the risk was 94% higher with Drug Y (HR 1.94). Since this 95% CI (1.35-2.78) also does not cross 1.0 and the P value is <0.05, this increased risk is also statistically significant. Therefore, Drug Y is more effective but less safe.
A 2-year-old asymptomatic child undergoes routine lead screening via a capillary (finger-stick) sample, which returns a level of 7 µg/dL. The child lives in a house built in the 1960s. The family recently began minor renovations. The physical examination is normal.
What is the most appropriate next step in the management of this child?
Explanation: The CDC reference value for an elevated blood lead level is 3.5 µg/dL. Any elevated result obtained from a capillary sample is subject to contamination and must be confirmed with a venous blood draw. Therefore, the first step is to obtain a confirmatory venous level. If the venous level is confirmed to be elevated (in the 5-14 µg/dL range), management involves education on environmental exposures, nutritional counseling (calcium, iron), and follow-up testing. (B) Chelation therapy is only indicated for much higher blood lead levels, typically ≥45 µg/dL. (C) There is no indication of medical neglect; the family is engaged in routine care. Reporting would be inappropriate. (D) A level of 7 µg/dL is considered elevated and requires action, not just reassurance. It indicates exposure that must be identified and mitigated.
A 38-year-old G1P1 woman with a history of chronic hypertension is seen at her 2-week postpartum visit. She is breastfeeding her infant. During pregnancy, her blood pressure was managed with labetalol. At today's visit, her blood pressure is 155/95 mm Hg. She is currently taking labetalol 200 mg twice daily. Which of the following is the most appropriate next step in managing her hypertension?
Explanation: This patient's blood pressure is not at goal. The most appropriate next step is to optimize her current medication, which is safe for breastfeeding. Labetalol is a first-line agent for postpartum hypertension and is considered safe in lactation. Increasing the dose of labetalol is the most logical step before adding or switching to another agent. ACE inhibitors (e.g., lisinopril) and angiotensin receptor blockers are generally avoided in breastfeeding due to theoretical concerns, although some are considered compatible. Thiazide diuretics may decrease milk production.
A 44-year-old male, a lifelong non-smoker, is evaluated for progressive dyspnea. Pulmonary function testing reveals an obstructive pattern with a post-bronchodilator FEV1 of 55% of predicted and a DLCO of 60% of predicted. A CT scan shows bilateral basilar panacinar emphysema. Genetic testing confirms a diagnosis of alpha-1 antitrypsin deficiency with a PiZZ genotype. He is up to date on vaccinations and is using tiotropium and albuterol as needed.
In addition to his current management, which of the following treatments is most appropriate for this patient?
Explanation: This patient has alpha-1 antitrypsin deficiency (AATD), a genetic cause of COPD. Intravenous augmentation therapy with pooled human alpha-1 proteinase inhibitor is indicated for patients with AATD and evidence of emphysema with an FEV1 between 30% and 65% of predicted. This therapy aims to slow the progression of emphysema. His FEV1 of 55% falls within this range. Inhaled corticosteroids are not routinely recommended in AATD unless there is concomitant asthma or frequent exacerbations. Referral for lung transplantation is premature at this FEV1 level. Long-term oral steroids are not indicated and have significant side effects.
A 50-year-old man has been in the ICU for two weeks recovering from severe thermal burns covering 40% of his body surface area. He has been receiving total parenteral nutrition (TPN) for the past 12 days. He develops a new fever to 39.0°C (102.2°F), right upper quadrant tenderness, and a white blood cell count of 16,000/mm³. An abdominal ultrasound shows a distended gallbladder with a thickened wall (>4 mm) and pericholecystic fluid, but no gallstones are visualized.
Explanation: When you encounter a critically ill patient with gallbladder symptoms but no stones on imaging, think acute acalculous cholecystitis (AAC). This condition typically affects patients with severe illness, prolonged fasting, or TPN use—exactly what we see here. This patient's presentation perfectly fits AAC: he's critically ill with severe burns, has been on prolonged TPN (12 days), and shows the classic triad of fever, right upper quadrant pain, and leukocytosis. The ultrasound findings of gallbladder wall thickening >4mm, distension, and pericholecystic fluid without stones clinch the diagnosis. AAC occurs because critical illness and prolonged fasting lead to gallbladder stasis and ischemia, causing inflammation without obstruction. Looking at the wrong answers: (A) Ascending cholangitis would present with Charcot's triad (fever, jaundice, RUQ pain) and typically requires biliary obstruction—you'd expect dilated bile ducts on imaging. (B) TPN-induced cholestasis causes jaundice and elevated bilirubin rather than acute inflammatory symptoms with normal bile ducts. (C) Acute pancreatitis would cause epigastric pain radiating to the back with elevated lipase/amylase, not the focused RUQ tenderness and gallbladder changes seen here. For USMLE Step 3, remember that AAC is a high-yield diagnosis in ICU patients. Key associations include major surgery, burns, sepsis, prolonged fasting, and TPN use. Unlike calculous cholecystitis, stones are absent, but the inflammatory findings on imaging are the same. Early recognition is crucial since AAC can rapidly progress to perforation.
A 27-year-old woman with sickle cell disease is transitioning from pediatric hematology to adult care. Background: Frequent pain crises; history of missed appointments; graduating college; wants more independence. Current status/Plan: On hydroxyurea; needs routine labs and vaccination updates. Team: Pediatric hematologist, adult hematologist, PCP, nurse care coordinator, social worker. Coordination: Adult team requests prior complication history and transfusion records; PCP to manage preventive care. Transition plan: Joint visit proposed; emergency plan reviewed. Which strategy best supports the patient's transition from pediatric to adult care?
Explanation: This question tests the ability to manage care coordination and transitions in primary care as per USMLE Step 3 standards. Effective care coordination involves seamless communication among healthcare providers and ensuring continuity of care, which is crucial for patient safety and reducing readmissions. In the given scenario, the patient's transition plan must include specific follow-up actions like joint visits and shared summaries, with responsibilities clearly assigned to prevent gaps in care during this sickle cell transition. The correct answer demonstrates the application of these principles by ensuring appropriate follow-up and clear communication among the care team through structured planning. A common distractor might suggest abrupt transfer or patient-independent search, which often leads to fragmentation of care and missed appointments. Teaching strategies include reinforcing the importance of clear documentation, regular team meetings, and involving the patient in the care plan to ensure adherence and satisfaction. Encourage students to practice scenario-based planning to visualize transitions effectively, such as simulating pediatric-to-adult handoffs.
A 33-year-old woman with systemic lupus erythematosus (SLE) is admitted to the ICU with diffuse alveolar hemorrhage. She is intubated and requires high FiO2. She is started on high-dose steroids and plasmapheresis. Despite this, she develops oliguric acute kidney injury and shock requiring norepinephrine. Her anti-double-stranded DNA antibody titers are markedly elevated, and her complement levels are low.
The patient's poor prognosis is best understood as a failure of which of the following?
Explanation: This patient has a catastrophic flare of her SLE, leading to multisystem organ failure (lungs, kidneys, cardiovascular system). The underlying pathophysiology is widespread autoimmune-mediated damage. The failure to respond to aggressive immunosuppression (steroids, plasmapheresis) indicates that the autoimmune process is not being controlled. This ongoing inflammatory damage is the root cause of the progressive organ failure and poor prognosis. While secondary infection (B) is a risk and failure of supportive care (C) is occurring, these are consequences of the uncontrolled primary disease process. The failure is not specific to plasmapheresis (D) but to the overall lack of response to the entire immunosuppressive regimen.
A 26-year-old G1P1 woman had a spontaneous preterm delivery at 32 weeks gestation in her first pregnancy. She is now attending a preconception counseling visit. She is otherwise healthy. She asks what can be done to reduce the risk of preterm birth in her next pregnancy. Which of the following interventions is most likely to reduce her risk of recurrent spontaneous preterm birth?
Explanation: For a woman with a singleton pregnancy and a history of a prior spontaneous preterm birth, progesterone supplementation is the primary evidence-based intervention to reduce the risk of recurrence. This is typically initiated at 16-24 weeks and continued until 36 weeks. Cervical cerclage is indicated for patients with a history of cervical insufficiency or a short cervix identified on ultrasound. Prophylactic antibiotics and bed rest have not been shown to be effective in preventing recurrent preterm birth.
A 36-year-old G1P1 is seen for her 6-week postpartum visit. Her pregnancy was complicated by diet-controlled gestational diabetes mellitus (GDM). She has been monitoring her fasting and postprandial glucose levels at home, and all values have been normal since delivery. She feels well and is asymptomatic. She asks about her future health risks.
Explanation: Women with a history of GDM have a seven-fold increased risk of developing type 2 diabetes later in life. ACOG and the American Diabetes Association recommend screening for persistent diabetes at 4 to 12 weeks postpartum. The preferred screening method is the 75-g, 2-hour oral glucose tolerance test (OGTT), as it is more sensitive than fasting glucose or HbA1c in this population. (A) Normalization of blood glucose after delivery is expected but does not eliminate the substantial future risk of type 2 diabetes. (C) Screening should begin in the postpartum period, not in 5 years, and if results are normal, repeat screening should occur at least every 1-3 years. (D) Lifestyle counseling regarding diet and exercise should be provided for long-term risk reduction, not just for future pregnancies.
A 16-year-old sexually active female requests contraception. She has a history of migraines with aura, which occur about twice per month. She has no other medical problems and does not smoke. Her blood pressure is 110/70 mm Hg.
Which of the following is the most appropriate contraceptive method to recommend for this patient?
Explanation: The use of estrogen-containing contraceptives (combined oral contraceptives, patch, ring) is contraindicated in women with migraine with aura due to an increased risk of ischemic stroke. Therefore, a progestin-only or non-hormonal method is recommended. The progestin-only subdermal implant is a highly effective, long-acting, reversible contraceptive that is safe for this patient. Other appropriate options would include the progestin-only pill, depot medroxyprogesterone acetate injection, hormonal IUD, or copper IUD. (A), (C), and (D) are all combined hormonal contraceptives containing estrogen and are therefore contraindicated in this patient due to her history of migraine with aura. This represents a WHO Medical Eligibility Criteria Category 4 (unacceptable health risk).
An 80-year-old woman with long-standing hypertension, coronary artery disease, and peripheral artery disease is started on ramipril. One week later, she complains of new-onset nausea and fatigue. Her blood pressure is 140/80 mmHg. Laboratory studies are significant for a serum creatinine that has increased from a baseline of 1.3 mg/dL to 2.9 mg/dL. This patient's acute kidney injury is most likely due to the new medication's effect on which of the following physiologic mechanisms?
Explanation: This patient with extensive atherosclerotic disease likely has underlying bilateral renal artery stenosis. In this condition, glomerular filtration rate (GFR) is maintained by angiotensin II-mediated vasoconstriction of the efferent arteriole. Initiating an ACE inhibitor (ramipril) blocks the production of angiotensin II, leading to vasodilation of the efferent arteriole. This causes a precipitous drop in intraglomerular pressure and a subsequent sharp decline in GFR, manifesting as acute kidney injury. Afferent arteriolar vasoconstriction is a mechanism of NSAID-induced AKI.
A 69-year-old man with HFrEF and chronic kidney disease (stage 3) is found to have a hemoglobin of 9.2 g/dL on routine labs. He reports increased fatigue. Evaluation reveals a ferritin of 45 ng/mL and a transferrin saturation (TSAT) of 15%. His folate and vitamin B12 levels are normal. Which of the following is the most appropriate management for his anemia?
Explanation: This patient has iron deficiency anemia (ferritin <100 ng/mL or ferritin 100-300 ng/mL with TSAT <20%), a common comorbidity in heart failure. In symptomatic HF patients with iron deficiency, intravenous iron repletion has been shown to improve symptoms, functional capacity, and quality of life. Oral iron (A) is often poorly absorbed and tolerated in HF patients due to gut edema and inflammation. Erythropoiesis-stimulating agents (C) have been associated with harm in this population and are not recommended. Transfusion (D) is reserved for acute hemodynamic instability or severe symptoms, not for chronic stable anemia at this level.
A 66-year-old man has CKD stage 5 for 9 years from diabetes; he is stable and not on dialysis. He takes insulin, carvedilol 12.5 mg twice daily, amlodipine 10 mg daily, torsemide 40 mg daily, and sevelamer with meals. He reports decreased appetite and mild nausea but no dyspnea or confusion. BP is 148/84 mm Hg. Exam shows 1+ edema. Labs: creatinine 6.2 mg/dL, eGFR 9 mL/min/1.73 m², K 5.1 mEq/L, HCO3 18 mEq/L, Ca 8.6 mg/dL, phosphate 6.4 mg/dL, Hgb 10.1 g/dL. Renal ultrasound shows small echogenic kidneys. Which referral is most appropriate for this patient?
Explanation: This question tests chronic kidney disease management skills, specifically focusing on evidence-based referral timing for renal replacement therapy in advanced CKD patients. Chronic kidney disease management involves regular monitoring of renal function, adjusting medications based on kidney status, and managing complications like anemia and electrolyte imbalances. In the presented vignette, the patient's eGFR of 9 and uremic symptoms indicate the need for predialysis education and planning. The correct choice, nephrology for renal replacement therapy education and planning, accurately reflects current guidelines for managing CKD stage 5, demonstrating the student's understanding of appropriate clinical interventions. A common distractor may suggest cardiology for stress testing, which is not routinely required, highlighting a frequent misconception. To improve understanding, students should focus on guidelines for dialysis initiation, regularly review eGFR trends, and practice identifying indications for specialist referral.
A 78-year-old man with a history of type 2 diabetes and hypertension is hospitalized for an acute pulmonary embolism. His baseline serum creatinine is 2.6 mg/dL, with an estimated GFR of 24 mL/min/1.73m². He is being transitioned from an intravenous heparin infusion to a long-term oral anticoagulant. Which of the following is the most appropriate choice for this patient?
Explanation: This patient has severe chronic kidney disease (CKD) with a GFR <30 mL/min. Most direct oral anticoagulants (DOACs) are renally cleared and are either contraindicated or require caution and have limited data in severe CKD. Rivaroxaban and dabigatran are contraindicated in the US for VTE treatment with a CrCl <30 mL/min. While apixaban can be used, its use is based on pharmacokinetic data rather than large trials in this population. Warfarin is not renally cleared and is the most studied and recommended oral anticoagulant for patients with severe CKD or end-stage renal disease. It should be initiated with a parenteral bridge (e.g., heparin or enoxaparin) until the INR is therapeutic.
A 38-year-old woman is seen for a 3-month follow-up visit after being diagnosed with a PE provoked by a 14-hour flight. She has been taking apixaban, and her symptoms have completely resolved. She is concerned and asks if she needs another CT scan to see if the clot has dissolved. What is the most appropriate response?
Explanation: Routine imaging (either CT or V/Q scan) to assess for clot resolution after a course of treatment for acute PE is not recommended in asymptomatic patients. The findings do not reliably predict recurrence risk and do not alter the planned duration of therapy, which is based on whether the PE was provoked or unprovoked and the patient's bleeding risk. Such imaging would lead to unnecessary radiation exposure, cost, and risk of contrast-induced nephropathy. Residual thrombus is a common finding and does not automatically necessitate lifelong therapy, especially for a provoked PE.