Following resection of the left colon, a 67-year-old obese woman develops left-sided leg edema due to deep-vein thrombosis. She is placed on anticoagulants, but after 2 weeks of warfarin (Coumadin), she develops a pulmonary embolus with slight hypoxemia. What should the next step in management involve?

**Core Concept**
The question tests the understanding of **anticoagulation therapy** and management of **venous thromboembolism (VTE)**, including **deep-vein thrombosis (DVT)** and **pulmonary embolism (PE)**. The scenario involves a patient on **warfarin** who develops a **pulmonary embolus**, necessitating a change in management.

**Why the Correct Answer is Right**
Given the patient's development of a pulmonary embolus despite being on warfarin, the next step involves **initiating a more effective or alternative anticoagulant**. This could include **low-molecular-weight heparin (LMWH)** or **direct oral anticoagulants (DOACs)**, which may offer a more predictable anticoagulant effect compared to warfarin. The choice depends on the patient's specific clinical scenario, including renal function and potential drug interactions.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because simply continuing warfarin without adjustment or addition of another anticoagulant may not adequately address the new pulmonary embolus.
**Option B:** Incorrect as it does not specify an appropriate alternative anticoagulant strategy.
**Option D:** Incorrect because, although **inferior vena cava (IVC) filter** placement can be considered in patients with contraindications to anticoagulation or those who have failed anticoagulant therapy, it is not the first-line next step for someone who can be managed with anticoagulants.

**Clinical Pearl / High-Yield Fact**
In patients with VTE, including DVT and PE, **prompt initiation of effective anticoagulation** is crucial to prevent further thromboembolic events. The choice of anticoagulant should be tailored to the individual patient's risk factors and clinical circumstances.

**Correct Answer:** C. Initiating therapeutic anticoagulation with a low-molecular-weight heparin or adjusting the current anticoagulation regimen.

✓ Correct Answer: C. Use of an inferior vena cava (IVC) filter