Anatomic and physiologic changes in lower extremity venous hemodynamics associated with pregnancy

Purpose: The purpose of this study was to describe the physiologic effects of pregnancy on lower extremity venous hemodynamics. Methods: Eight pregnant women, six with no known venous disease (NVD) and two with documented deep venous obstruction (DVO), were identified in the first trimester (TM) and studied monthly until delivery and once postpartum (pp) by air plethysmography and duplex scan. Results: None of six women in the NVD group (12 extremities) had obstruction or elevated ambulatory venous pressures as estimated by air plethysmography. In addition, despite significant increases in common femoral vein and saphenofemoral junction diameters, no woman in the NVD group had reflux by either test. Venous filling index increased significantly during pregnancy and decreased significantly pp, but all values remained within the normal range (0.55 +/- 0.2 ml/sec first TM, 1.01 +/- 0.38 ml/sec late third TM, 0.58 +/- 0.08 ml/sec pp; p < 0.03 both comparisons). Common femoral vein diameters increased and decreased in similar fashion (0.99 +/- 0.25 cm first TM, 1.21 +/- 0.25 cm late third TM, 0.80 +/- 0.11 cm pp; p < 0.0005 first vs late third TM, p < 0.005 late third TM vs pp). Saphenofemoral junction vein diameters similarly increased and decreased in size (0.46 +/- 0.07 cm first TM, 0.68 +/- 0.19 cm late third TM, 0.50 +/- 0.10 cm pp; p < 0.01 first vs late third TM, p < 0.03 late third TM vs pp). Neither of the two women in the DVO group showed deterioration of outflow fraction or venous filling index as pregnancy progressed, and neither had thromboembolic complications despite moderate to severe preexisting obstruction. Both women in the DVO group delivered uneventfully. No woman in either group developed varicose veins. Conclusion: Pregnancy-induced changes in lower extremity venous hemodynamics in the NVD and DVO groups were detected but were small. Hormonal or other systemic factors must play a significant role in the development of postpartum varicose veins.