Left versus right intra-abdominal umbilical arteries: comparison of their Doppler waveforms.

OBJECTIVES: The purpose of this study was to compare Doppler velocimetric indices between the left and right intra-abdominal umbilical arteries in normally grown and growth-restricted fetuses. METHODS: In this cross-sectional study, Doppler indices of the intra-abdominal segment of the left and right umbilical arteries were measured lateral to the fetal bladder. Measurements, including the systolic to diastolic ratio and pulsatility index, were obtained from both anatomic locations. The Student t test was used to make comparisons. RESULTS: Differences between left and right Doppler indices were noted in 98% of patients, and these differences were greater than 20% in at least one-third. Overall, the left umbilical artery had a higher systolic to diastolic ratio (P = .025) and pulsatility index (P = .007) than the right umbilical artery. CONCLUSIONS: The laterality of the umbilical artery, whether on the left or right side of the fetus, influences important Doppler blood flow parameters.