TRANSVERSE UMBILICAL ARTERIAL DIAMETER - TECHNIQUE FOR THE PRENATAL-DIAGNOSIS OF SINGLE UMBILICAL ARTERY

We investigated the relationship between the transverse umbilical arte rial diameter and the presence of a single umbilical artery. Further, we speculated that fetal physiologic and hemodynamic limitations in pr egnancies complicated by a single umbilical artery would result in lar ger umbilical arterial diameters than the typical three-vessel cord. T he identification of a sufficiently large umbilical artery may be path ognomonic for single umbilical artery. The transverse umbilical arteri al diameter was obtained in 100 consecutive, uncomplicated singleton p regnancies between 20 and 38 weeks' gestation. These measurements were compared with the transverse umbilical arterial diameter of 23 pregna ncies in which a single umbilical artery was identified with ultrasono graphy and postnatal examination. Transverse umbilical arterial diamet er measurements of the two groups were compared. Before 36 weeks' gest ation, all pregnancies with a single umbilical artery had a transverse umbilical arterial diameter measurement > 4 mm and all pregnancies wi th two umbilical arteries had a transverse umbilical arterial diameter measurement less than or equal to 4 mm. Because oligohydramnios, mult iple pregnancy, or suboptimal cord position may obscure the expeditiou s identification of the number of umbilical cord vessels, measurement of the transverse umbilical arterial diameter may prove useful in the identification of single umbilical artery. On the basis of this prelim inary evaluation, we suggest that a transverse umbilical arterial diam eter measurement > 4 mm is predictive of single umbilical artery betwe en 20 and 36 weeks' gestation.-