Ultrasound measurements of umbilical cord transverse area in normal pregnancies and pregnancies complicated by diabetes mellitus.

OBJECTIVE: A voluminous umbilical cord has been described in diabetic pregnancies. The aim of this studywas to see if measurements of cord diameters might be of value in the evaluation of diabetic pregnancies and especially those suspected of a large for gestational age (LGA) fetus. METHODS: In an observational, prospective study umbilical cord areas and vessel diameters were measured between gestational age of 22 and 40 weeks in transverse ultrasound images of the central part of the cord in 141 normal and 135 diabetic pregnancies of which 30 were suspected of being LGA. Wharton's jelly area was calculated by subtracting the vessel area from the total transverse cord area. Normal reference curves were constructed for gestational age. RESULTS: Umbilical cord and Wharton's jelly areas increased with gestation. The vessel area leveled out at 32-33 weeks of gestation and the umbilical vein area decreased after 36 weeks of gestation. The umbilical cord parameters in diabetic pregnancies did not differ from controls. Cord areas were enlarged in 1/3 of the LGA fetuses. CONCLUSION: Umbilical cord area measurements are of limited value for the evaluation of diabetic pregnancies suspected having a LGA-fetus.