Single umbilical artery: a Doppler flow velocity study of four cases

We measured the pulsatility index of the umbilical artery in four fetuses identified as having a single umbilical artery. A pulsed color Doppler ultrasound machine was used and measurements were performed at 4-week intervals following the first diagnosis of single umbilical artery (week 22-34). The pulsatility index was derived from the mean of five consecutive measurements at the umbilical insertion of the cord, taking care to obtain the Doppler signal with an incidence angle between +45 degrees and -15 degrees. All measurements were taken during periods of fetal inactivity. The pulsatility index at 22, 26, 30, 34 and 38 weeks in these pregnancies did not differ significantly from the mean values registered in normal pregnancies. The four women gave birth to babies of normal weight: two were healthy, one suffered from bladder extrophy and hemispondyly, the other had bilateral dilatation of the renal pelves, megalocystis, megalourethra and an imperforate anus.