Understanding the problem

The risk of VTE is increased 10 to 20 times in pregnancy compared to the general population. This is in part due to some changes in hormone levels and to compression of veins in the legs by the enlarging uterus. Doctors worry about VTE during pregnancy, as it is a leading cause of maternal death in Western countries.

VTE can be difficult to identify during pregnancy because some signs overlap with changes that occur in a regular pregnancy (e.g., shortness of breath, lower extremity swelling). In patients who have symptoms but are not pregnant, doctors use a checklist of questions (score) to decide if the patient is likely or unlikely to have DVT or PE. A D-dimer blood test is often combined with the score from the checklist to decide who needs imaging and who does not. In pregnancy, these tools are not typically used because they have not been well studied.

VTE is usually ruled out with imaging (ultrasound of the legs or CT scan of the chest) during pregnancy. The amount of radiation due to a CT scan of the chest during pregnancy is well below the accepted level for safety for both mom and baby. Nevertheless, concerns about radiation exposure can cause anxiety in pregnant patients. Recently, studies have looked at the role of the D-dimer in ruling out VTE in pregnant patients. The reviewers wanted to know if using a D-dimer blood test can safely rule out VTE in pregnant patients without the need for imaging.