Nuchal cord in normal third-trimester pregnancy: a color Doppler imaging study.

A prospective study was performed in a normal, unselected, population of 180 pregnant women to assess the screening properties of color Doppler imaging in the detection of nuchal cord during the third trimester of pregnancy. A search was made for the umbilical cord position initially using conventional real-time gray-scale imaging and subsequently using color imaging. Umbilical artery resistance and pulsatility indices and maximum peak systolic velocity were measured in each case at the level of the placental cord insertion. Forty-five (25%) cases examined using color imaging presented with a nuchal cord at both ultrasound examination and delivery. Color imaging correctly identified in utero 28 (72%) single and 17 (94%) multiple nuchal cords found at birth. The overall sensitivity of color imaging in detecting nuchal cord prenatally was greater than for gray-scale imaging (79% compared with 33%). The sensitivity of color imaging was also higher after 36 weeks than before (93% compared with 67%). No difference was observed between the umbilical artery resistance and pulsatility indices. There was also no difference observed for the maximum peak systolic velocity between cases presenting with a nuchal cord (at both ultrasound examination and delivery) and controls matched for gestational age. We suggest that the clinical usefulness of systematic identification in utero of nuchal cord in pregnancies presenting with a normal fetus in the vertex position is limited, but might be of value in the management of breech and twin gestations, and also in the management of chronically growth-retarded fetuses. Copyright 1992 International Society of Ultrasound in Obstetrics and Gynecology