Ultrasound detection of nuchal cord prior to labor induction and the risk of Cesarean section.
OBJECTIVE
To investigate the ability of ultrasound to detect the presence of a nuchal cord immediately prior to induction of labor and the association of its presence with delivery by Cesarean section.


METHODS
A transabdominal ultrasound scan using gray-scale and color Doppler imaging was performed immediately prior to induction of labor in 289 women in a prospective study to assess the presence of a nuchal cord. The presence of a nuchal cord was classified as present, absent or uncertain. The outcomes of labor, delivery and the neonates were obtained from the patient notes after delivery.


RESULTS
A nuchal cord was present at 18% of deliveries. The incidence was not affected by parity, fetal position or reduced amniotic fluid volume. The sensitivity of ultrasound in diagnosing a nuchal cord was 37.5%, with specificity, positive and negative predictive values of 80%, 29% and 85%, respectively. The presence of a nuchal cord did not significantly increase the risk of delivery by Cesarean section (35% vs. 28%; relative risk = 1.22; 95% CI, 0.80-1.87), instrumental delivery for fetal distress, an abnormal cardiotocograph in labor or at delivery, an Apgar score < 7 at 1 min, arterial cord pH < 7.1 or neonatal unit admission.


CONCLUSIONS
The sensitivity of the ultrasound diagnosis of a nuchal cord is low prior to induction of labor at term. A nuchal cord does not appear to increase the risk of Cesarean section or of poor neonatal outcome. The low ultrasound detection rate of a nuchal cord limits its use in decision making prior to induction of labor in high-risk pregnancies.
Peregrine
E
E
Department of Obstetrics and Gynaecology, University College London Hospitals, London, UK.
O'Brien
P
P
Jauniaux
E
E
D002585:Cesarean Section / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007751:Labor, Induced / Q000379:methods*; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards; D014470:Umbilical Cord / Q000000981:diagnostic imaging*