Vaginosonographic velocimetry in uterine arteries before and after administration of beta-mimetics

Abstract

Objective: To investigate the effect of surgical procedures at 15 weeks gestation (amniocentesis or cervical cerclage), with or without post-operative ritodrine prophylaxis, on uterine blood flow velocity waveforms and maternal heart rate.

Design: A quasi-randomized observational study.

Setting: University Department of Obstetrics and Gynaecology, Vienna.

Subjects: Sixty women having a genetic amniocentesis for advanced maternal age and 57 women having elective cervical cerclage for previous preterm labour or recurrent miscarriage.

Interventions: The women in each group were allocated either to receive prophylactic ritodrine postoperatively or to receive no ritodrine treatment. Allocation used the year of birth of the woman (odd years received ritodrine, even years received no treatment). All the women had vaginal ultrasound velocimetry studies in both mainstem uterine arteries through the parametrium before the surgical procedure and again after the procedure. The ritodrine-treated women in the cerclage group received intraveneous ritodrine hydrochloride (0.2 mg/min) and those in the amniocentesis group received 60 mg ritodrine/day orally.

Main outcome measures: Uterine artery blood flow velocity waveform indices: A/B ratio and pulsatility index (PI) and maternal heart rate before and after the surgical procedure.

Results: The only statistically significant difference in haemodynamic values between those obtained before the procedure and those obtained after the procedure with or without prophylactic ritodrine was seen in the women who had cervical cerclage with postoperative intravenous ritodrine. The mean A/B ratio decreased from 2.69 (SD 1.17) to 2.11 (SD 0.44), and the mean PI from 1.62 (SD 0.47) to 1.21 (SD 0.3) and the mean maternal heart rate increased from 82.6 (SD 11.1) to 99.4 (SD 15.7). There were no other statistically significant differences between before and after haemodynamic values.

Conclusions: There are no clinically relevant effects of amniocentesis and cervical cerclage on uterine blood flow velocity waveforms.