Venous Thromboembolism Prevention and Diagnosis

Diagnostic Approach

The European Society of Cardiology recommends using D-dimer testing to rule out VTE, with a negative result indicating low likelihood of VTE, and a positive result prompting further imaging with bilateral compression ultrasonography of lower limbs 1
If ultrasonography is negative but clinical suspicion remains high, additional testing with MRI or CT pulmonary angiography may be needed, with MRI being the preferred option if available due to no radiation exposure 1
A negative D-dimer has a high negative predictive value for excluding PE in pregnant women, similar to non-pregnant patients, as stated by the American College of Cardiology and the European Society of Cardiology 2, 3, 1
The following table summarizes normal D-dimer levels during pregnancy:
Trimester D-dimer Level (μg/mL)
First 0.11-0.40
Second 0.14-0.75
Third 0.16-1.3

The European Society of Cardiology recommends risk stratification for prophylaxis based on risk factors, not D-dimer levels, with high-risk patients receiving LMWH prophylaxis for 6 weeks postpartum and graduated compression stockings 1
Intermediate-risk patients should receive LMWH prophylaxis for at least 7 days postpartum or longer if >3 risk factors persist, and consider graduated compression stockings 1
Low-risk patients should focus on early mobilization and avoid dehydration, as recommended by the European Society of Cardiology 1

The American College of Cardiology recommends treatment based on heparin anticoagulation, with low molecular weight heparin (LMWH) as the preferred treatment during pregnancy, using weight-adjusted dosing 2, 1
D-dimer levels can be used to monitor treatment effectiveness, with decreasing levels suggesting effective treatment and persistently elevated levels indicating treatment failure or ongoing thrombosis, as recommended by the International Society on Thrombosis and Haemostasis 5
The D-dimer level remains elevated for approximately 7-14 days after a thrombotic event, and serial measurements are more informative than isolated values, as stated by the European Society of Cardiology 6, 7
Age-adjusted cutoffs (age × 10 μg/L for patients >50 years) may improve specificity without compromising safety, as recommended by the American College of Cardiology 5
Blood samples for D-dimer testing should be drawn peripherally to avoid heparin contamination from central lines, as recommended by the American Heart Association and the European Society of Cardiology 8, 1