What is the management for an adult patient with an intermediate Wells score for pulmonary embolism (PE) and no significant contraindications?

Management of Intermediate Wells Score for Pulmonary Embolism

For patients with an intermediate Wells score (2-6 points) for suspected PE, obtain a highly sensitive D-dimer test—if negative, PE is excluded without imaging; if positive, proceed directly to CT pulmonary angiography (CTPA). 1

Risk Stratification Context

• Intermediate Wells score (2-6 points) carries a 13-30% probability of PE, with most studies showing rates between 20-29% 1
• This intermediate-risk category represents approximately 28-63% of patients evaluated for PE, making it the most common risk group encountered 1

Diagnostic Algorithm

Step 1: D-Dimer Testing

• Order a highly sensitive quantitative D-dimer test (ELISA or turbidimetric assay) as the next step after intermediate Wells score determination 1
• A negative D-dimer (<500 ng/mL) in intermediate-risk patients reduces the post-test probability of PE to less than 1.85%, safely excluding PE without imaging 2
• If D-dimer is negative, withhold anticoagulation and no further testing is needed 1

Step 2: Imaging When D-Dimer is Positive

• Proceed to multidetector CT pulmonary angiography (CTPA) for all intermediate-risk patients with positive D-dimer 1
• CTPA has 95% sensitivity for segmental or larger PE, though sensitivity drops to approximately 75% for subsegmental PE 1
• V/Q scanning remains an alternative if CTPA is contraindicated (contrast allergy, renal insufficiency, pregnancy concerns) 3

Step 3: Additional Testing After Negative CTPA

• For intermediate pretest probability patients with negative CTPA in whom clinical concern persists, consider additional diagnostic testing before excluding VTE 1
• Options include: bilateral lower extremity ultrasound, highly sensitive D-dimer if not already performed, V/Q scanning, or traditional pulmonary arteriography 1
• This recommendation stems from data showing 1.3-2.0% of intermediate-risk patients develop VTE during 3-month follow-up after negative CTPA alone 1

Anticoagulation Management

Pending Diagnosis

• Administer low molecular weight heparin (LMWH) while awaiting imaging if there will be any delay in obtaining definitive testing 1
• One study showed 62.8% of intermediate-risk patients received same-day imaging after LMWH dose, with 89% imaged within 24 hours 1

Confirmed PE Treatment

• Initiate direct oral anticoagulants (DOACs) as first-line therapy for confirmed PE with systolic blood pressure ≥90 mmHg 1, 4, 2
• Rivaroxaban: 15 mg twice daily for 3 weeks, then 20 mg once daily 1, 4
• Apixaban: 10 mg twice daily for 7 days, then 5 mg twice daily 1
• Edoxaban or dabigatran: requires ≥5 days of LMWH first, then transition 1
• DOACs are noninferior to warfarin for treating PE and have 0.6% lower absolute bleeding rates 2

Critical Pitfalls to Avoid

• Do not skip D-dimer testing and proceed directly to imaging in intermediate-risk patients—this approach increases radiation exposure and cost without improving outcomes 1
• Do not rely on CTPA alone in intermediate-risk patients with high clinical suspicion despite negative imaging—the false-negative rate is 1.8% in this population, with inpatients having higher rates (4.8%) than outpatients (0.8%) 1
• Avoid using less sensitive D-dimer assays (whole blood qualitative or immunofiltration methods) as standalone tests—these have lower negative predictive value and should only be used with Wells scoring systems 1
• Do not use gestalt assessment alone without structured scoring—while gestalt and Wells score perform similarly (both identifying ~3% PE rate in low-risk groups), structured tools improve consistency and documentation 1

Special Considerations

• In patients aged ≥50 years with intermediate Wells score, consider age-adjusted D-dimer thresholds (age × 10 ng/mL) to improve specificity while maintaining safety 1
• For pregnant patients, D-dimer has very low specificity (0.18-0.21) beyond first trimester—proceed directly to imaging if intermediate Wells score 1
• Renal function does not require dose adjustment for rivaroxaban in PE treatment if CrCl ≥15 mL/min, though patients with CrCl <30 mL/min were not studied 4