USMLE Step 3 Quiz: Pulmonary Embolism And Anticoagulation Follow Up
20 questions · exam conditions
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Pulmonary Embolism And Anticoagulation Follow UpQuestion 1 of 20

A 58-year-old man with unprovoked PE completes 6 months of apixaban with no bleeding. Which management is best?

Stop and check D-dimer monthly
Continue apixaban indefinitely
Switch to aspirin 81 mg daily
Repeat leg ultrasound now
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USMLE Step 3 Quiz

USMLE Step 3 Quiz: Pulmonary Embolism And Anticoagulation Follow Up

Practice Pulmonary Embolism And Anticoagulation Follow Up in USMLE Step 3 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Pulmonary Embolism And Anticoagulation Follow Up, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 3.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A 58-year-old man with unprovoked PE completes 6 months of apixaban with no bleeding. Which management is best?

  1. Stop and check D-dimer monthly
  2. Continue apixaban indefinitely (correct answer)
  3. Switch to aspirin 81 mg daily
  4. Repeat leg ultrasound now
Explanation: An unprovoked PE carries a substantial recurrence risk, and after 6 months of apixaban without bleeding, continued anticoagulation is recommended. Switching to aspirin is tempting but is less effective at preventing recurrent VTE and is not the preferred strategy. Stopping to monitor D-dimer or repeating ultrasound does not guide management here.

Question 2

A patient with active cancer and PE has recurrent PE while adherent to enoxaparin. Best next step?

  1. Add aspirin 81 mg daily
  2. Switch to warfarin, INR 2-3
  3. Insert IVC filter alone
  4. Increase enoxaparin by 25% (correct answer)
Explanation: Recurrent PE on therapeutic enoxaparin in active cancer means the current dose is insufficient; guidelines recommend increasing LMWH by 25% rather than changing agents. Warfarin is the tempting choice because it is an anticoagulant, but cancer-associated VTE responds less reliably to warfarin, and IVC filter alone or aspirin doesn't treat the underlying thrombosis.

Question 3

A pregnant patient on LMWH for acute PE asks how her dose should be monitored. Best response?

  1. Warfarin after trimester one
  2. Fondaparinux once weekly
  3. Check PT/INR each visit
  4. Anti-Xa levels guide dose (correct answer)
Explanation: Pregnancy changes LMWH clearance and volume of distribution, so anti-Xa levels are used to monitor and adjust the dose. Checking PT/INR is tempting, but that tests warfarin, not LMWH, and warfarin is not the right agent for monitoring or continuation in early pregnancy.

Question 4

A patient on warfarin for PE has a subdural hematoma and INR 4.0. Best management?

  1. Fresh frozen plasma alone
  2. Hold warfarin, repeat INR
  3. PCC, IV vitamin K, hold (correct answer)
  4. Oral vitamin K 5 mg only
Explanation: Life-threatening bleeding on warfarin needs immediate reversal. PCC rapidly restores the vitamin K-dependent factors, while IV vitamin K restarts synthesis and keeps INR down, and warfarin is held. The tempting wrong choice is fresh frozen plasma alone: it supplies factors but is slower, requires large volume, and does not reliably correct INR 4.0 in an emergency.

Question 5

Six months after PE, which finding best suggests CTEPH?

  1. Mismatched V/Q, mPAP 35 mmHg (correct answer)
  2. Normal D-dimer and leg US
  3. Asymmetric leg swelling
  4. New V1-V4 T-wave inversion
Explanation: A mismatched V/Q scan shows persistent perfusion defects from chronic thromboemboli, and mPAP 35 mmHg confirms pulmonary hypertension, so together they diagnose CTEPH at 6 months. New V1-V4 T-wave inversion is tempting but only suggests right ventricular strain and is not specific for chronic thromboembolic disease.

Question 6

A 47-year-old man on long-term anticoagulation for PE 3 months ago (provoked by long-haul flight and obesity) presents with new pleuritic chest pain and dyspnea on exertion. He is taking apixaban 5 mg twice daily; he admits missing several evening doses over the last week. No hemoptysis. Vitals: BP 132/80, HR 108, RR 22, SpO2 93% RA. Exam shows mild right calf tenderness. Labs: INR 1.1, creatinine 0.9 mg/dL (eGFR 95 mL/min/1.73 m²), troponin negative. He has no contraindications to contrast. What is the most appropriate next step in management for this patient?

  1. Reassure and schedule routine follow-up because he is already anticoagulated
  2. Obtain CT pulmonary angiography to evaluate for recurrent pulmonary embolism (correct answer)
  3. Stop apixaban and start warfarin without parenteral bridging therapy
  4. Start NSAIDs for pleurisy and defer imaging until symptoms persist one week
Explanation: This question tests the understanding of pulmonary embolism management and anticoagulation follow-up in a clinical context relevant to USMLE Step 3. The principle focus is on applying clinical guidelines for anticoagulation management and recognizing complications arising from therapy. In this scenario, factors such as the patient's missed apixaban doses, new pleuritic chest pain, dyspnea, tachycardia, and hypoxia are critical for decision-making. The correct answer addresses these factors by suggesting CT pulmonary angiography to evaluate for recurrent pulmonary embolism, demonstrating the application of clinical guidelines for suspected recurrence in nonadherent patients. A common distractor might suggest reassurance without imaging, which fails to consider the risk of recurrence due to missed doses. To prepare for similar questions, students should focus on understanding anticoagulation management guidelines, recognize symptoms indicative of complications, and practice applying this knowledge to case scenarios.

Question 7

A 55-year-old woman with recurrent unprovoked PE (two episodes, last 14 months ago) presents for routine anticoagulation follow-up. Risk factors include prior estrogen-containing OCP use (stopped), obesity, and strong family history of VTE; she has no active cancer. She is on warfarin with target INR 2.0–3.0, monitored every 4 weeks; last two INRs were 2.4 and 2.6. She now reports 3 days of dark stools, lightheadedness on standing, and increased bruising; no chest pain or dyspnea. Vitals: BP 104/66, HR 102, SpO2 98% RA. Exam shows conjunctival pallor and ecchymoses. Labs today: INR 3.8, Hgb 8.7 g/dL (baseline 12.1), platelets 210k, BUN 34 mg/dL, creatinine 1.3 mg/dL (eGFR 52 mL/min/1.73 m²). She recently started ibuprofen for back pain. What is the most appropriate next step in management for this patient?

  1. Hold warfarin, administer reversal, and evaluate for gastrointestinal bleeding source urgently (correct answer)
  2. Continue warfarin and add a proton pump inhibitor without further evaluation
  3. Switch to aspirin monotherapy and schedule outpatient colonoscopy in three months
  4. Increase warfarin dose to maintain INR 3.5–4.5 for recurrent PE prevention
Explanation: This question tests the understanding of pulmonary embolism management and anticoagulation follow-up in a clinical context relevant to USMLE Step 3. The principle focus is on applying clinical guidelines for anticoagulation management and recognizing complications arising from therapy. In this scenario, factors such as the patient's INR of 3.8, dark stools, lightheadedness, hemoglobin drop, and recent ibuprofen use are critical for decision-making. The correct answer addresses these factors by suggesting holding warfarin, administering reversal, and urgently evaluating for gastrointestinal bleeding, demonstrating the application of clinical guidelines for major bleeding events. A common distractor might suggest continuing warfarin and adding a proton pump inhibitor, which fails to consider the urgency of reversal and evaluation in active bleeding. To prepare for similar questions, students should focus on understanding anticoagulation management guidelines, recognize symptoms indicative of complications, and practice applying this knowledge to case scenarios.

Question 8

Patient takes warfarin after unprovoked PE 9 months ago. Elective surgery in 5 days. Plan?

  1. Stop warfarin now; bridge LMWH
  2. Continue warfarin; no bridge
  3. Hold warfarin 1 day; no bridge
  4. Stop warfarin now; no bridge (correct answer)
Explanation: Warfarin must be held 5 days before surgery to normalize the INR. A VTE 3 to 12 months earlier puts this patient in the MODERATE perioperative risk tier, not the low tier, which requires more than 12 months. Even so, bridging is not indicated: trial evidence shows LMWH bridging adds bleeding risk without reducing thromboembolism outside the highest-risk groups. The tempting error is to bridge anyway, which is reserved for very recent VTE, severe thrombophilia, or a mechanical valve.

Question 9

After 6 months of apixaban for PE, her breast cancer still requires chemotherapy. Best plan?

  1. Stop apixaban after 6 months
  2. Continue full-dose apixaban (correct answer)
  3. Switch to enoxaparin 40 mg
  4. Switch apixaban to warfarin
Explanation: Active cancer plus chemotherapy keeps the patient at high risk for recurrent venous thromboembolism, so anticoagulation should continue beyond 6 months at full treatment dose. Apixaban is a preferred DOAC for cancer-associated thrombosis. The tempting error is stopping at 6 months, which applies to provoked PE without ongoing cancer; enoxaparin 40 mg is only prophylaxis, not treatment.

Question 10

Stable recurrent PE despite therapeutic rivaroxaban. Next step?

  1. Add aspirin 81 mg daily
  2. Place retrievable IVC filter
  3. Switch to therapeutic LMWH (correct answer)
  4. Increase rivaroxaban to 30 mg
Explanation: Recurrent PE while on therapeutic rivaroxaban indicates anticoagulation failure, so the next step is to switch to therapeutic LMWH, which provides more reliable and alternative anticoagulation. An IVC filter is the tempting choice, but it only blocks clot passage and does not treat the underlying hypercoagulable state.

Question 11

PE patient on warfarin has INR 9 and mild epistaxis. Best management?

  1. Hold warfarin; IV vitamin K
  2. Hold warfarin; oral vitamin K (correct answer)
  3. Give fresh frozen plasma only
  4. Continue warfarin; repeat INR
Explanation: With INR 9 and only mild epistaxis, you need to hold warfarin and give oral vitamin K to reverse anticoagulation without the urgency of IV therapy. IV vitamin K is for serious or life-threatening bleeding, while FFP alone doesn't correct the vitamin K-dependent factor deficiency durably. Continuing warfarin with INR 9 risks worsening bleeding.

Question 12

A 48-year-old woman weighing 150 kg (BMI 51 kg/m²) is being treated for an unprovoked pulmonary embolism. The medical team is selecting an oral anticoagulant for her long-term management. Which of the following is the most appropriate consideration?

  1. Fixed-dose apixaban is preferred due to its favorable safety profile in all populations.
  2. Low-molecular-weight heparin is the only appropriate long-term option.
  3. Dabigatran should be used as it is not affected by body weight.
  4. Warfarin is a preferred agent due to the ability to monitor its effect with the INR. (correct answer)
Explanation: When treating venous thromboembolism in patients with extreme obesity (BMI >40 kg/m² or weight >120 kg), you need to consider how body weight affects anticoagulant dosing and monitoring capabilities. Warfarin remains the preferred choice for morbidly obese patients because it can be precisely monitored and dose-adjusted using INR values, regardless of body weight. The INR directly measures the anticoagulant effect, allowing clinicians to ensure therapeutic levels are maintained even in patients with altered drug distribution due to extreme obesity. Choice A is incorrect because fixed-dose direct oral anticoagulants (DOACs) like apixaban haven't been adequately studied in patients weighing >120 kg. The standard fixed doses may provide subtherapeutic levels in morbidly obese patients, potentially leading to treatment failure. Choice B is wrong because low-molecular-weight heparin is typically used for short-term or bridging therapy, not long-term management. It's also impractical for extended outpatient use due to the need for daily injections. Choice C is incorrect because dabigatran, like other DOACs, lacks sufficient data in extreme obesity. While it's true that dabigatran has less weight-based dosing variation than some other drugs, there's still concern about adequate drug exposure in patients >120 kg, and unlike warfarin, you cannot monitor its anticoagulant effect with routine lab tests. Remember: In extreme obesity (BMI >40 or weight >120 kg), choose anticoagulants that allow therapeutic monitoring. Warfarin's ability to be monitored with INR makes it the safest choice when DOAC efficacy data is limited.

Question 13

A 45-year-old woman is evaluated after completing 3 months of apixaban for a first-time unprovoked pulmonary embolism. She feels well and has no complaints. Her medical history is otherwise unremarkable, and she is calculated to have a low risk of bleeding. Which of the following is the most appropriate recommendation?

  1. Stop apixaban as the initial treatment course is complete.
  2. Stop apixaban and begin daily low-dose aspirin.
  3. Continue apixaban indefinitely with periodic reassessment. (correct answer)
  4. Obtain a ventilation-perfusion scan to assess for residual clot.
Explanation: For a first-time unprovoked pulmonary embolism, the risk of recurrence after stopping anticoagulation is high (approximately 10% in the first year). In a patient with a low bleeding risk, guidelines recommend extended anticoagulation therapy to prevent recurrence. This involves continuing apixaban indefinitely, with at least annual reassessment of the risks and benefits. Stopping therapy would leave her at high risk for a recurrent, potentially fatal PE. Aspirin is significantly less effective than anticoagulation for VTE prevention. Follow-up imaging is not recommended as it does not change management.

Question 14

A 29-year-old woman who was diagnosed with an unprovoked pulmonary embolism 4 months ago presents for follow-up. She has been taking rivaroxaban 20 mg daily. She reports a positive home pregnancy test, and a subsequent ultrasound confirms a 6-week intrauterine pregnancy. What is the most appropriate management of her anticoagulation?

  1. Continue rivaroxaban, as it is effective and convenient.
  2. Stop rivaroxaban and switch to therapeutic-dose enoxaparin. (correct answer)
  3. Stop rivaroxaban and switch to warfarin with a target INR of 2.0-3.0.
  4. Discontinue all anticoagulation until after delivery.
Explanation: Direct oral anticoagulants (DOACs) like rivaroxaban are contraindicated in pregnancy due to lack of safety data and potential for fetotoxicity. Warfarin is teratogenic, especially during the first trimester. The anticoagulant of choice during pregnancy is low-molecular-weight heparin (LMWH), such as enoxaparin, as it does not cross the placenta. Discontinuing anticoagulation is unsafe due to the high risk of recurrent VTE, which is further increased by pregnancy.

Question 15

A 32-year-old woman presents for follow-up 3 months after being diagnosed with a pulmonary embolism. The event occurred six weeks after she started taking a combined oral contraceptive pill. She has completed a 3-month course of apixaban and is asymptomatic. She has no family history of blood clots. Which of the following is the most accurate statement regarding testing for inherited thrombophilias?

  1. Testing should be performed now to determine if lifelong anticoagulation is required.
  2. Testing is not indicated because the PE was provoked and the results will not alter management. (correct answer)
  3. Testing for Factor V Leiden is mandatory to guide her future contraceptive choices.
  4. Testing should have been done before starting apixaban to rule out contraindications.
Explanation: This patient had a pulmonary embolism provoked by a major, modifiable risk factor (oral contraceptives). The standard treatment is a finite course (3 months) of anticoagulation. Testing for inherited thrombophilias is generally not recommended in this setting because the results would not change the management plan. The presence of a thrombophilia would not extend the duration of therapy for a clearly provoked event. Regardless of thrombophilia status, she will be advised to avoid estrogen-containing contraceptives in the future.

Question 16

A 44-year-old woman who was treated for a large, bilateral pulmonary embolism 8 months ago with a 6-month course of rivaroxaban now presents with progressive exertional dyspnea. Her oxygen saturation is 96% on room air. An echocardiogram reveals an estimated right ventricular systolic pressure of 60 mmHg and right ventricular dilation. What is the most appropriate next step in diagnosis?

  1. Repeat CT pulmonary angiography.
  2. Ventilation-perfusion (V/Q) scan. (correct answer)
  3. Right heart catheterization.
  4. Six-minute walk test.
Explanation: This patient's presentation is highly suspicious for chronic thromboembolic pulmonary hypertension (CTEPH), a serious complication of acute PE. The initial screening test of choice for CTEPH is a ventilation-perfusion (V/Q) scan due to its high sensitivity; a normal V/Q scan essentially rules out CTEPH. While CTPA may show signs of chronic PE, it is less sensitive than a V/Q scan. Right heart catheterization is the gold standard for confirming the diagnosis of pulmonary hypertension and assessing its severity, but it is an invasive procedure performed after non-invasive screening suggests the diagnosis. A six-minute walk test assesses functional capacity but is not diagnostic.

Question 17

A 42-year-old woman with a known diagnosis of high-risk antiphospholipid syndrome (positive for all three antibody types) is hospitalized with an acute pulmonary embolism. She has a prior history of a cerebral ischemic attack. What is the most appropriate anticoagulant for long-term secondary prevention in this patient?

  1. Apixaban.
  2. Warfarin with a target INR of 2.0-3.0. (correct answer)
  3. Rivaroxaban.
  4. Low-dose aspirin monotherapy.
Explanation: For patients with antiphospholipid syndrome (APS), particularly high-risk patients (triple-positive or with a history of arterial thrombosis), warfarin remains the standard of care for treating VTE. Clinical trials have suggested that direct oral anticoagulants (DOACs) may be associated with a higher rate of recurrent thrombosis, especially arterial events, compared to warfarin in this specific population. Therefore, DOACs like apixaban and rivaroxaban should be avoided. Aspirin monotherapy is inadequate for VTE treatment.

Question 18

A 28-year-old competitive runner was diagnosed with a PE two weeks ago. He was started on apixaban and his shortness of breath has resolved. He is hemodynamically stable and eager to resume training. What is the most appropriate advice regarding physical activity?

  1. He must avoid all strenuous activity until his 3-month course of anticoagulation is complete.
  2. He can begin a gradual return to his training regimen as tolerated, avoiding contact sports. (correct answer)
  3. He should remain on bed rest for two more weeks to prevent thrombus dislodgement.
  4. He can resume training immediately with no restrictions, as anticoagulation is protective.
Explanation: Early ambulation and a gradual return to physical activity are encouraged after an acute PE as soon as the patient is hemodynamically stable and symptoms allow. Prolonged immobility is a risk factor for VTE. The main restriction while on anticoagulation is to avoid activities with a high risk of traumatic injury and bleeding (e.g., contact sports). Therefore, a gradual, sensible return to running is appropriate. Bed rest is contraindicated. An immediate return to full-intensity training without a gradual ramp-up is not advisable.

Question 19

A 66-year-old man on warfarin for a PE has an INR of 4.5 at a routine follow-up visit. He has no signs of active bleeding. He reports that he recently took a course of ciprofloxacin for a urinary tract infection. What is the most appropriate next step in management?

  1. Administer 2.5 mg of oral vitamin K.
  2. Continue the current warfarin dose and advise him to avoid antibiotics.
  3. Admit the patient for fresh frozen plasma transfusion.
  4. Hold the warfarin dose for today and recheck the INR in 1-2 days. (correct answer)
Explanation: When managing warfarin overdose, your approach depends on the degree of INR elevation and presence of bleeding. This patient has a supratherapeutic INR (4.5) without active bleeding, likely due to ciprofloxacin inhibiting warfarin metabolism through CYP450 interactions. For INR levels between 4.5-10 without bleeding, the standard approach is to hold warfarin temporarily and monitor closely. The INR will naturally decrease as warfarin's effect wanes (warfarin has a half-life of 36-42 hours). This allows for safe correction without risking overcorrection that could lead to thrombotic complications. Choice D is correct because holding warfarin and rechecking INR in 1-2 days allows controlled monitoring of the INR decline while maintaining anticoagulation benefits as the ciprofloxacin effect diminishes. Choice A (oral vitamin K 2.5 mg) would be appropriate for INR >10 without bleeding, but risks overcorrection and warfarin resistance for several days. Choice B ignores the dangerous INR elevation - continuing warfarin could worsen the coagulopathy, and avoiding all antibiotics isn't realistic long-term management. Choice C (FFP transfusion) is reserved for life-threatening bleeding or emergency surgery needs, as it's expensive, carries transfusion risks, and provides only temporary reversal. Key strategy: Remember the INR thresholds for warfarin management: 3-5 without bleeding = hold doses and monitor; 5-9 without bleeding = hold and consider low-dose vitamin K; >9 or any bleeding = vitamin K; life-threatening bleeding = vitamin K plus FFP/PCC.

Question 20

A 52-year-old woman is being followed for a PE that was treated with 6 months of apixaban, which was stopped 2 years ago. She has remained asymptomatic. Today, she presents for a pre-operative evaluation for an elective hysterectomy. What is the most appropriate recommendation for VTE prophylaxis?

  1. No prophylaxis is needed as her PE was fully treated.
  2. She requires bridging therapy with enoxaparin and post-operative warfarin.
  3. She should receive standard peri-operative pharmacologic prophylaxis per surgical guidelines. (correct answer)
  4. She should be restarted on her full treatment dose of apixaban post-operatively.
Explanation: A history of VTE places a patient at a higher baseline risk for future events, especially in high-risk situations like major surgery. However, she is not on active treatment. The correct approach is to risk-stratify her for the specific procedure (hysterectomy is moderate-to-high risk) and provide standard peri-operative VTE prophylaxis (e.g., LMWH or unfractionated heparin) according to established guidelines. Restarting full-dose anticoagulation or using bridging therapy is not indicated, as she does not have an active clot. Forgoing prophylaxis entirely would be unsafe given her history.