Perinatal outcomes of abnormal umbilical coiling according to a modified umbilical coiling index

The aim of this study was to determine the relation between perinatal outcomes and umbilical cord coiling as evaluated by a modified umbilical coiling index.

In this retrospective study, 200 consecutive umbilical cords were examined. An umbilical venous and arterial coiling index was calculated by dividing the total number of umbilical venous and arterial coils by the length of cord individually. Umbilical cords with umbilical venous coiling indices in the lowest decile, the highest decile, and the remaining deciles were defined as hypocoiled, hypercoiled, and normocoiled, respectively. The perinatal outcomes of the subjects with hypocoiled and hypercoiled umbilical cords were compared with those with normocoiled umbilical cords.

In 69.5% of subjects, a difference in the degree of coiling was detected between the umbilical veins and arteries. While all umbilical venous twisting demonstrated the same direction, the direction of the arterial twisting reversed at a certain point along the umbilical cord in 19.0% of the subjects. The arteriovenous coiling difference was small in the hypercoiled group and large in the hypocoiled group. A hypocoiled umbilical cord evaluated by umbilical venous coiling index was found to be associated with prolonged deceleration (odds ratio [OR], 4.18; 95% confidence interval [CI], 1.54-11.38), operative delivery (OR, 2.67; 95%CI, 1.01-7.09), and nuchal cord entanglement (OR, 3.21; 95%CI, 1.23-8.33).

Umbilical coiling abnormalities were investigated using a novel umbilical venous coiling index. A hypocoiled umbilical cord evaluated by umbilical venous coiling index was found to be associated with fetal heart rate abnormalities, operative delivery, and nuchal cord entanglement.