Should pulmonary embolism (PE) be ruled out in a pregnant patient who previously experienced symptoms but is currently asymptomatic?

Pulmonary Embolism in Pregnancy: Diagnostic Approach When Symptoms Resolve

A formal diagnostic assessment with validated methods is absolutely necessary if pulmonary embolism (PE) is suspected during pregnancy, even if symptoms have resolved at the time of evaluation. 1

Diagnostic Algorithm for Suspected PE in Pregnancy

Initial Assessment

• Apply the modified Wells score (cutoff ≥6 points) to evaluate PE probability 2
• Assess for symptoms of deep vein thrombosis (DVT) 2
• Note that DVT history is a significant risk factor for PE during pregnancy (odds ratio 9.4) 2

Diagnostic Pathway

1. If DVT symptoms are present:

   • Perform bilateral compression ultrasound (CUS) of lower extremities 2
   • If CUS is positive: Begin anticoagulation without further imaging
   • If CUS is negative: Proceed to chest imaging

2. Chest Imaging Pathway:

   • Start with chest X-ray 2
   • If chest X-ray is normal: Proceed to ventilation-perfusion (V/Q) scan
   • If chest X-ray is abnormal: Proceed to CTPA
   • If V/Q scan is non-diagnostic: Proceed to CTPA

Important Considerations

• D-dimer testing should be considered but cannot reliably rule out PE in pregnancy due to documented false negatives 2
• Clinical symptoms alone should never be relied upon to exclude PE in pregnancy due to overlap with normal pregnancy symptoms 2

Management While Awaiting Diagnosis

If clinical suspicion remains high while awaiting definitive diagnosis:

• Initiate therapeutic anticoagulation with low molecular weight heparin (LMWH) 2
• Continue anticoagulation until PE is definitively ruled out 2

Radiation Considerations

Modality	Maternal Breast Radiation	Fetal Radiation
V/Q scan	0.16-1.2 mGy	0.02-0.60 mGy
CTPA	3-10 mGy	0.05-0.5 mGy

• Keep radiation dose as low as reasonably achievable 2
• For V/Q scan: Use half the usual administered activity of Tc-99m macroaggregated albumin and increase scan time 2
• For CTPA: Adjust technical factors for maternal size and limit scan length 2

Multidisciplinary Approach

A multidisciplinary pregnancy heart team should collaborate in planning care pathways for pregnant women with suspected PE 1:

• Maternal-fetal medicine specialists
• Cardiologists
• Emergency physicians

Pitfalls to Avoid

1. Overreliance on symptom resolution: PE symptoms may be transient or fluctuating, but the underlying clot remains a significant risk 3

2. Overdiagnosis concerns: While avoiding overdiagnosis is important (due to implications for bleeding risk during delivery, contraception restrictions, and future pregnancy thromboprophylaxis requirements), missing a PE diagnosis is more dangerous 1

3. Assuming PE is ruled out without proper imaging: Many PE cases are asymptomatic or have nonspecific symptoms that overlap with normal pregnancy 3

4. Delaying anticoagulation: If clinical suspicion is high and bleeding risk is low, anticoagulation should be initiated while awaiting diagnostic results 2

In summary, a pregnant patient who previously experienced PE symptoms but is currently asymptomatic still requires complete diagnostic evaluation with appropriate imaging studies. The transient nature of symptoms does not rule out the presence of a pulmonary embolism, which remains a leading cause of maternal mortality.