Doppler blood flow velocity waveforms of the umbilical artery during variable decelerations in labor

Abstract

Objective: To investigate the changes in resistance indices of blood flow velocity waveforms of the umbilical artery (UmA-RIs) during variable decelerations (VDs) vs. early decelerations (EDs). Methods: UmA-RIs were measured before and during uterine contractions in 30 cases with VDs, nine cases with EDs and 20 cases without decelerations. In 12 out of 30 cases with VDs, UmA-RI was determined at the following five stages of a VD; before the deceleration, downward, bottom, upward and resumption stages. Results: UmA-RIs during VDs were significantly higher compared with those at preceding periods. UmA-RIs at downward and bottom stages of VDs were significantly higher than those at the upward stage, although no differences in heart rate were found between downward and upward stages. UmA-RIs during EDs or uterine contractions without decelerations did not differ from those preceding them. Conclusion: UmA-RIs increased during VDs, particularly at downward and bottom stages during which the cord seemed to be actually compressed.