Late normalisation of uterine artery velocimetry in high risk pregnancy

OBJECTIVE: To test whether late normalisation of abnormal uterine velocimetry is a favourable prognostic factor in high risk pregnancies. STUDY DESIGN: Uterine artery colour Doppler velocimetry was performed at 24, 28-30 and 32-34 weeks in 282 high risk pregnancies treated with low dose aspirin. RESULTS: 88 patients had abnormal waveforms at 24 weeks and 77 delivered after the second assessment at 28 weeks. Of these, 38 (49%) had a normalisation of Doppler indices by 34 weeks. Compared with the persistently abnormal Doppler group, these patients delivered fewer small for gestational age babies (5/38 versus 26/39; p=0.0001) and had less gestational hypertension without proteinuria (3/38 versus 15/39; p=0.004). No patients with preeclampsia or other severe complications of pregnancy were observed in the normalised group. CONCLUSIONS: Although abnormal uterine artery velocimetry at 24 weeks is predictive of adverse pregnancy outcome, nearly half have late normalisation of the Doppler indices and a better perinatal outcome. Persistently abnormal waveforms are related to the worst pregnancy outcome.