The umbilical coiling index.
OBJECTIVE: Our purpose was to objectively quantitate umbilical vascular coiling. STUDY DESIGN: In this prospective study the umbilical cords and delivery records of 100 consecutive liveborn neonates were studied. The umbilical coiling index of each cord was determined by dividing the total number of complete umbilical vascular coils by the umbilical cord length (in centimeters). The obstetric history, intrapartum fetal heart rate tracing, and pregnancy outcome of each fetus were evaluated without knowledge of the umbilical coiling index. RESULTS: The mean umbilical coiling index was 0.21 +/- 0.07 (SD) coils per centimeter. The 100 values were normally distributed. Among those whose umbilical coiling index values fell < or = 10th percentile, there was a significantly greater incidence of karyotypic abnormalities (p = 0.04), meconium staining (p = 0.03), and operative intervention for fetal distress (p = 0.03). There was a significantly greater incidence of moderate or severe variable fetal heart rate decelerations for those whose umbilical coiling index value was either < or = 10th percentile (0.1 coils per centimeter) or > 90th percentile (0.3 coils per centimeter) (p = 0.03). CONCLUSION: The umbilical coiling index may have utility for objectively describing the degree of umbilical vascular coiling.