Color doppler ultrasonography evaluation of nuchal cord before induction of labor in postterm pregnancies

ABSTRACT

To asses the ability of color Doppler ultrasonography to detect the presence of nuchal cord [NC] before induction of labor in uncomplicated postterm pregnancies, and to investigate whether fetal umbilical artery vascular resistance, mode of delivery, and neonatal outcome are affected by its presence in such cases. In a prospective study, a transabdominal grayscale and color Doppler ultrasound imaging was performed prior to induction of labor in 250 women with uncomplicated postterm pregnancies at 41 weeks to detect the presence of nuchal cord and to measure the umbilical artery [UA] systolic/diastolic ratio [S/D] and resistance index [RI]. The outcomes of labor, delivery and neonates were obtained. Outcome parameters evaluated included presence of nuchal cords at delivery, mode of delivery, non-reassuring fetal heart rate patterns [NRFHR], meconium-stained amniotic fluid, birth weight, 1 and 5 minutes Apgar scores, and admission to neonatal intensive care unit. A total of 250 women were included in this study, of which 71 had sonographic evidence of NC [group I] and 179 without sonographic evidence of NC [group II]. A nuchal cord was present at 26.8% of deliveries. The sensitivity of color Doppler sonography in diagnosing NC was 94%, with specificity, positive and negative predictive values of 95.6%, 88.7%, and 97.7%, respectively. No abnormal UA waveform patterns were detected in either group, and no statistically significant differences in UA S/D or RI values were found between the two study groups. There were also no significant differences between group I and group II with respect to mode of delivery, NRFHR, meconium-stained amniotic fluid, birth weight, 1 and 5 minutes Apgar scores, and neonatal intensive care unit admissions. Color Doppler ultrasonography is highly sensitive and specific method of diagnosing nuchal cord prior to induction of labor in uncomplicated postterm pregnancies. However, fetal umbilical artery vascular resistance, mode of delivery, and neonatal outcome are not affected by cord encirclement in such cases. Therefore, ultrasonographic nuchal cord assessment is neither a necessary nor a useful procedure before labor induction in uncomplicated postterm pregnancies, and intrapartum intervention based on the antenatal diagnosis may not be appropriate