Lower Extremity Venous Cross-Sectional Area Changes Associated With Pregnancy

Objective.—This study aimed to assess the effect of posture on lower-extremity vein areas in primigravida women during pregnancy and postpartum.

Methods.—Real-time duplex ultrasound was used to study 39 primigravida women (with no evidence of varicose veins or peripheral vascular disease) during pregnancy and postpartum to determine the areas of the superficial and deep leg veins. Vein areas where measured with the subjects in both supine and erect positions. These areas were than compared statistically for any differences between the right and left leg and for the significance of changes that occurred as the result of advancing pregnancy. The reversibility of pregnancy-induced changes was determined by comparison of postpartum results.

Results.—No statistically significant differences were found between the veins of the right and left leg. Veins areas increased as pregnancy advanced and decreased postpartum. All vein areas measured with the subject in the erect position were larger than those obtained in the supine position. Vein area increases associated with advancing pregnancy were significant when measured in the supine position. Although vein areas measured in the erect position showed a similar trend, they did not show statistically significant changes.

Conclusion.—Vein areas increased early in pregnancy and with advancing pregnancy continued to enlarge significantly when the subject was in the supine position. With the subject in the erect position, venous compliance reached a plateau by midpregnancy. With the veins then fully distended, the pregnancy induced changes, which continued with advancing pregnancy (blood volume expansion, hormonally induced decreased smooth muscle tone, pelvic vascular compression) coupled with increased hydrostatic pressure in the erect position must result in increased lower extremity venous pressure. The pregnancy induced vein changes were reversible postpartum.