Relationship between the umbilical cord coiling index and the umbilical blood flow at 11-13weeks of gestation

Objectives: The aim of this study was to clarify the effects of umbilical cord coiling on the umbilical blood flow at 11-13weeks of gestation. Methods: A cross-sectional study was conducted among consecutive pregnant females at 11-13weeks of gestation. Transabdominal ultrasound examinations were performed to obtain the umbilical coiling index (CI), the maximum umbilical arterial peak velocity at the free loop, the venous velocities at the free loop and the umbilical ring, and the umbilical arterial and venous flow volumes. After every measurement was standardized according to the crown-rump length (CRL), correlations between the CI and these measurements were analyzed. Results: A total of 364 subjects were enrolled. The CI significantly decreased in association with advancing gestation. There were significant correlations between the CRLs and the umbilical arterial peak velocities, the venous velocities at the free loop and the umbilical ring, and the umbilical arterial and venous flow volumes. The z-scores of the umbilical arterial and venous velocimetries exhibited no significant correlations with the CI. The umbilical arterial and venous flow volumes were also not found to correlate with the CI. Conclusions: The CI does not affect either the umbilical arterial or venous blood flow at 11-13weeks of gestation.