Antenatal umbilical coiling index as a predictor of perinatal outcome.

Purpose: To evaluate the relationship between sonographic measurements of umbilical cord coiling index during late second trimester of pregnancy and perinatal outcome.
Methods: This prospective study was conducted on two hundred pregnant women with uncomplicated, singleton pregnancy between 20 to 24 weeks of gestation. The antenatal umbilical coiling index (UCI) was calculated by doing a transabdominal ultrasound at the time of induction into the study as the reciprocal of the pitch of one complete vascular coil. The patients were followed up till delivery and any adverse antenatal and/or perinatal event was noted.
Results: The mean value for the UCI was noted to be 0.36 + 0.07 coils/cm with a 95% CI of 0.35-0.37. The values for the 10th and the 90th percentile were 0.26 and 0.46 coils/cm respectively. Accordingly the cases were divided into three groups- hypocoiled (UCI <10th percentile)-18, normocoiled (UCI between 10th-90th percentile)-162 and hypercoiled (UCI >90th percentile)-20. Hypocoiling was observed to be significantly associated with preterm labour pains (P value 0.0344), oligohydramnios (P value 0.0021), intrapartum foetal heart rate abnormalities (P value 0.0012), instrumental vaginal delivery (P value 0.0275) and low birth weight (P value 0.0344). Hypercoiling was found to be significantly associated with intrauterine growth restriction (P value 0.0323), foetal heart rate abnormalities during labour (0.0399) and low birth weight (P value 0.0095).
Conclusion: Abnormal umbilical coiling index in the form of either hypo- or hypercoiling is associated with several adverse antenatal and neonatal outcomes.