Structural-tridimensional study of yolk sac in pregnancies complicated by diabetes

To assess by two- and three-dimensional ultrasound the diameter and volume of the yolk sac in pregnant women affected by type 1 diabetes during the first trimester of pregnancy.

18 women affected by insulin-dependent diabetes mellitus (IDDM) and 52 normoglycemic pregnant women (controls) were enrolled in this study. The women were evaluated once a week (5-12 weeks of pregnancy). Ultrasound examination in all pregnant women was initially performed in a bidimensional fashion with a transvaginal 6.5-MHz probe and subsequently using a three-dimensional technique.

In the pregnant diabetic women the diameter of the yolk sac was significantly higher than that of controls in the first weeks of pregnancy, reaching a maximum diameter at 9 weeks, and decreasing thereafter, earlier than controls. The volume of the yolk sac increased in both groups from 5 weeks of pregnancy and reached maximum values at 10 weeks in both groups. The volumetric increase and decrease after reaching highest values were greater in IDDM patients.

The clinical and diagnostic implications of the results of this study are still to be defined. Such a diagnostic technique may prove to be an additional element in monitoring diabetic women during early pregnancy.