Color ultrasonography: a useful technique in the identification of nuchal cord during labor

To compare the accuracy of intrapartum ultrasound with and without color Doppler for identification of nuchal cord displacement during labor.

180 normal pregnant women, admitted in labor, or for induction to labor, were examined independently by two researchers, using either conventional real-time gray-scale imaging or color Doppler imaging. A repeat examination was performed by the other researcher using the other ultrasound modality. Nuchal cord displacement was classified as either negative, definite or suspicious. Nuchal cord at birth was classified as either tight or loose.

Sixty-two (34%) cases examined using the two ultrasound imaging modalities presented with nuchal cord at delivery. The sensitivity of color Doppler was 96.8%. The accuracy of color Doppler in detecting nuchal cord during labor was significantly better (P < 0.05) than gray-scale imaging alone. The results of a restricted sequential t-test analysis of 53 un-tied pairs showed an overall preference in favor of color Doppler assessment: statistical significance (P < 0.01) was reached after 41 un-tied pairs.

The tight and loose nuchal cord could not be distinguished by ultrasound. Color Doppler imaging can provide useful additional information to gray-scale imaging in the detection of nuchal cord displacement during labor.