Wells Criteria for Pulmonary Embolism

The Score

Interpretation

3-Tier (Original)

2-Tier (Simplified / Dichotomized)

Clinical Application

1. Wells ≤4 (PE unlikely) → Order a D-dimer
   • Negative D-dimer: PE excluded, no further imaging needed
   • Positive D-dimer: proceed to CT pulmonary angiography (CTPA)
2. Wells >4 (PE likely) → Proceed directly to CTPA (D-dimer not useful here — high pretest probability means a negative D-dimer does not exclude PE)
3. Age-adjusted D-dimer: In patients with low-to-moderate Wells scores, D-dimer thresholds can be adjusted upward (age × 10 µg/L for patients >50) to reduce unnecessary imaging.

Key Points

• The "alternative diagnosis less likely than PE" criterion (3 pts) and "clinical signs of DVT" (3 pts) are the two highest-weight items — together they can push a patient into "PE likely" territory on their own.
• The score performs best in outpatient and ED populations; it was not designed for ICU patients or those already on anticoagulation.
• The simplified Wells score (each criterion = 1 point, total ≤1 = unlikely) is also used but has less granularity.

Management of Pulmonary Embolism

Step 1 — Risk Stratification

Step 2 — Immediate Supportive Care

• Oxygen: Correct hypoxemia; target SpO₂ >90%
• IV fluids: Use cautiously — aggressive volume loading worsens RV dilation and increases wall tension → RV ischemia. Limit to ~500 mL bolus
• Vasopressors: Norepinephrine is preferred for hemodynamic support in massive PE
• Dobutamine: May augment RV output; combination with norepinephrine can be used
• Mechanical ventilation (if needed): Use low tidal volumes (~6 mL/kg), keep plateau pressure <30 cmH₂O; positive-pressure ventilation reduces preload and can precipitate RV collapse
• ECMO: Reserved for refractory hemodynamic collapse as a bridge to surgical embolectomy (per ESC 2019 guidelines); risk of significant bleeding in ~35%

Step 3 — Anticoagulation

Anticoagulant Regimens

• DOACs are first-line for most patients (noninferior to VKA, less major bleeding, no monitoring required)
• UFH is preferred when thrombolysis or embolectomy may be needed (short-acting, reversible)
• DOACs are contraindicated in: severe renal impairment (CrCl <15–30 mL/min depending on agent), severe hepatic impairment, triple-positive antiphospholipid syndrome, pregnancy
• Warfarin requires overlap with parenteral anticoagulation ≥5 days and INR >2.0 on two occasions before stopping heparin
• Reversal agents: Idarucizumab (dabigatran), Andexanet alfa (rivaroxaban, apixaban, edoxaban)

Duration of Therapy

Step 4 — Reperfusion (Massive + Selected Submassive PE)

Systemic Thrombolysis

• Indication: Massive PE without absolute contraindications
• Agent: Alteplase (tPA) 100 mg IV over 2 hours (or 0.6 mg/kg over 15 min in cardiac arrest)
• Evidence: RCT (PEITHO trial) showed significant reduction in all-cause mortality + hemodynamic decompensation vs. anticoagulation alone
• Absolute contraindications: Prior intracranial hemorrhage, ischemic stroke <3 months, active bleeding, intracranial neoplasm, recent head trauma

Catheter-Directed Thrombolysis (CDT)

• Lower-dose thrombolytic delivered directly via catheter into pulmonary artery
• Used when systemic thrombolysis is contraindicated or has failed
• Also for submassive PE with deterioration

Surgical Embolectomy (Trendelenburg procedure)

• Reserved for: massive PE + absolute contraindication to thrombolysis, or failed thrombolysis
• Requires rapid cardiothoracic surgical mobilization

Mechanical Thrombectomy

• Newer devices (e.g., FlowTriever, AngioVac) allow catheter-based clot extraction
• Growing evidence for immediate hemodynamic improvement in massive PE
• No large RCTs yet

Step 5 — Special Situations

IVC Filter

• Only if absolute contraindication to anticoagulation (active hemorrhage, hemorrhagic stroke)
• Not recommended routinely in addition to anticoagulation
• Retrievable filters preferred — remove as soon as anticoagulation is safe

Outpatient Management (Low-Risk PE)

• Hemodynamically stable
• No active bleeding or high bleed risk
• SpO₂ maintainable >90% on room air
• No IV thrombolysis needed
• No severe comorbidity (renal/hepatic failure, active malignancy)

PE in Pregnancy

• LMWH is the anticoagulant of choice (DOACs and warfarin are contraindicated)

Cancer-Associated PE

• LMWH or DOACs (edoxaban, rivaroxaban) preferred over warfarin
• Caution with DOACs in luminal GI cancers (higher GI bleeding risk)

Step 6 — Multidisciplinary PE Response Team (PERT)