Suspected Pulmonary Embolism with Severe Renal Impairment

Pretest probability is moderate-to-high (Wells ≈6: clinical signs of DVT 3, heart rate >100 1.5, prolonged travel 1.5). She is in the "PE likely" tier.

Why D-dimer fails her:

• D-dimer is only used to exclude PE in low/intermediate pretest probability. In a "PE likely" patient a negative result does not safely exclude disease, so a positive result would not change the plan anyway.
• Chronic kidney disease independently elevates D-dimer, so her result is likely to be falsely positive, which would push her toward imaging and a contrast exposure. Ordering it adds cost and confusion without information.

Next step - pursue imaging, but choose the study deliberately:

1. Bilateral lower extremity ultrasound first. She has leg symptoms; a proximal DVT would confirm VTE and let you treat without any contrast at all.
2. If ultrasound is negative, ventilation-perfusion scanning (SPECT V/Q) is attractive because her chest radiograph is normal and her eGFR is 28 - this avoids iodinated contrast and the small risk of contrast-associated kidney injury. CTPA remains acceptable and is more available; many centers proceed with it after hydration, accepting the small renal risk in a hemodynamically stable patient. If CTPA is chosen, do not delay it for prolonged hydration in a symptomatic patient.
3. A normal CXR is what makes V/Q interpretable - document it.

She is low risk by hemodynamics (normotensive, normal troponin), so anticoagulation alone is appropriate - no thrombolysis.

Agent selection at eGFR 28:

• Apixaban is the most attractive oral option: it has the lowest renal clearance of the direct oral anticoagulants (about 27%) and is not contraindicated in severe renal impairment in most labeling, though use is cautious below a creatinine clearance of 25.
• Enoxaparin is a reasonable alternative, but with a creatinine clearance near 30, dose-adjust (e.g., 1 mg/kg once daily rather than twice daily) and consider anti-Xa monitoring.
• Avoid dabigatran (contraindicated at CrCl <30) and be cautious with rivaroxaban and edoxaban (limited data at this level of function).
• Warfarin is acceptable but is a poor choice for a young woman of childbearing potential unless pregnancy is excluded and reliable contraception is ensured.

Do today:

• Stop the combined oral contraceptive - an ongoing estrogen exposure is the provoking factor.
• Pregnancy test before any anticoagulant decision, because it changes the drug class entirely (low-molecular-weight heparin).
• Avoid NSAIDs; counsel on bleeding.
• Decide duration: provoking factor removed generally means at least 3 months, then reassess.

Interim management:

• Give empiric anticoagulation now if there is no active bleeding and no severe thrombocytopenia. Her pretest probability is high, the delay is real, and the risk of a subsequent embolic event in an untreated proximal clot outweighs the bleeding risk of a few hours of therapy. Document the reasoning.
• Provide supplemental oxygen if she desaturates, and analgesia that is not an NSAID.
• Keep her ambulatory-safe; do not encourage strict bed rest as a therapeutic measure, but avoid strenuous activity until the diagnosis is settled.

What would change the plan to reperfusion:

• Hemodynamic instability - sustained hypotension, a systolic blood pressure below 90 mmHg, a vasopressor requirement, or cardiac arrest. That defines high-risk (massive) PE and warrants systemic thrombolysis (e.g., alteplase) unless contraindicated, with catheter-directed therapy or surgical embolectomy as backup.
• Intermediate-high risk (right ventricular dilation on echocardiography or CT plus an elevated troponin) without hypotension is generally treated with anticoagulation and close monitoring, with rescue reperfusion reserved for clinical deterioration - not upfront lysis.

Her normal troponin and normal blood pressure put her in the low-risk category; the therapeutic lever to reach for is anticoagulation and disposition, not the thrombolytic.