What is the workup for Deep Vein Thrombosis (DVT) in pregnancy?

From the Guidelines

The workup for deep vein thrombosis (DVT) in pregnancy should begin with a thorough clinical assessment, followed by D-dimer testing and compression ultrasonography of the affected limb, as recommended by the European Society of Cardiology 1. When DVT is suspected in a pregnant woman, compression ultrasonography is the first-line imaging test due to its safety, lack of radiation exposure, and high sensitivity for proximal DVT.

• D-dimer testing is less useful in pregnancy as levels naturally increase throughout gestation, leading to more false positives.
• If ultrasound results are negative but clinical suspicion remains high, serial ultrasound examinations may be performed 5-7 days apart.
• For suspected pelvic vein thrombosis not visualized on ultrasound, magnetic resonance venography (MRV) without gadolinium is preferred. Key considerations in the workup of DVT in pregnancy include:
• Assessing pre-test probability
• Using D-dimer testing as an initial screening tool
• Performing compression ultrasonography as the primary diagnostic imaging modality
• Considering serial ultrasound examinations or MRV for cases with high clinical suspicion and negative initial imaging The American College of Chest Physicians also recommends the use of low-molecular-weight heparin for the prevention and treatment of VTE in pregnant women 1. Once DVT is confirmed, therapeutic anticoagulation should be initiated promptly with low molecular weight heparin (LMWH) such as enoxaparin 1 mg/kg twice daily or dalteparin 100 units/kg twice daily.
• LMWH is preferred over unfractionated heparin or warfarin due to its safety profile in pregnancy, reduced risk of heparin-induced thrombocytopenia, and minimal placental transfer.
• Anticoagulation should continue throughout pregnancy and for at least 6 weeks postpartum, with a minimum total duration of 3 months. Regular monitoring of platelet counts is recommended during the first two weeks of therapy, and patients should be educated about injection technique, signs of bleeding, and when to seek medical attention.

From the Research

Diagnostic Approach for Deep Vein Thrombosis (DVT) in Pregnancy

The workup for DVT in pregnancy typically involves a combination of clinical assessment and imaging studies. The following are key points to consider:

• A single complete color duplex ultrasonography of the lower limbs veins appears to be a safe method to rule out the diagnosis of DVT in pregnant women, and if negative, it is safe to withhold heparin therapy 2.
• Serial compression ultrasonography with Doppler imaging of the iliac vein performed over a 7-day period can exclude DVT in symptomatic pregnant women 3.
• The accuracy of diagnostic tests for DVT in pregnancy, including compression ultrasonography (CUS), ventilation-perfusion scintigraphy (VQ scan), and helical computed tomography (hCT), has not been extensively validated in pregnancy 4.
• Whole-leg compression ultrasound (CUS) can be used to evaluate suspected DVT in pregnant women, with a low rate of symptomatic DVT in patients with a negative initial whole-leg CUS 5.
• The pooled false-negative rate of a single ultrasound for suspected DVT in pregnancy is low, at 1.27% (95% confidence interval, 0.42-2.56) 6.

Imaging Studies

Some key points to consider when selecting imaging studies for DVT in pregnancy include:

• Color duplex ultrasound is a commonly used imaging modality for diagnosing DVT in pregnancy 2.
• Serial compression ultrasonography with Doppler imaging of the iliac vein can be used to exclude DVT in symptomatic pregnant women 3.
• Whole-leg compression ultrasound (CUS) can be used to evaluate suspected DVT in pregnant women 5.
• The choice of imaging study may depend on the clinical presentation and risk factors for DVT in the individual patient.

Clinical Assessment

Clinical assessment is an essential component of the workup for DVT in pregnancy. Some key points to consider include:

• Clinical suspicion of DVT is based on symptoms such as leg swelling, pain, and discoloration 2, 3.
• Pre-test probability scores and D-dimer levels can be used to inform the decision to perform imaging studies 4, 5.
• Patients with a high clinical suspicion of DVT and negative imaging studies may require further evaluation and follow-up 2, 3.