Lower limb vein enlargement and spontaneous blood flow echogenicity are normal sonographic findings during pregnancy

We studied pregnancy-induced changes in lower limb venous function.

We used plethysmography and sonography to assess the changes in venous wall distensibility, saphenous vein diameters, and spontaneous blood flow echogenicity in the common femoral veins in 190 consecutive women during and after uncomplicated pregnancies (total of 409 examinations).

The percentage of women with clinical symptoms and signs of venous insufficiency increased significantly during pregnancy. The mean diameters of the great and small saphenous veins also increased significantly, while occlusive venous plethysmography showed a decrease in parameters indicating vein distensibility. Spontaneous blood flow echogenicity in the common femoral veins was clearly visible or marked in 6% of cases during the first trimester of pregnancy, 63% during the second trimester, and 96% during the third trimester, versus 6% after delivery (p < 0.0001). The mean hematocrit decreased and the mean fibrinogen concentration increased during pregnancy.

The increase in lower limb venous pressure seen during pregnancy leads to venous overdistention and worsens blood stasis. Decreased venous flow velocity and rheological alterations result in increased red cell aggregation, giving rise to spontaneous blood flow echogenicity. Spontaneous blood flow echogenicity is therefore a normal finding during pregnancy and should not be mistaken for venous thrombosis.