Umbilical Cord Coiling

Abstract

The umbilical cord has a characteristic coiling pattern with both arteries coiling around the umbilical vein. This architecture is intrinsic to the cord and cannot be undone by unwinding in the opposite direction, unlike torsion. The number of coils divided by the length of the cord is the umbilical coiling index (UCI). The coiling index is preferably determined using fresh unfixed placentas. Abnormal cord coiling, defined as a hypo-coiled (UCI <10th centile) or hyper-coiled (>90th centile), is associated with fetal demise, fetal intolerance to labour, fetal growth restriction, chorioamnionitis and fetal vascular malperfusion.