Changes in velocimetric indices of uterine and umbilical arteries before and after combined spinal epidural analgesia in laboring women: a prospective cohort study.

BACKGROUND

Although combined spinal epidural (CSE) analgesia is an effective technique for labor analgesia, concerns regarding fetal bradycardia still remain. Increased vascular resistance of the uterine (UtA) and/or umbilical arteries (UmA) after CSE could explain the reported occurrence of fetal bradycardia. The aim of this study was to assess the changes in the resistance of UmA and UtA before and after initiation of CSE labor analgesia using ultrasound Doppler pulsatility index (PI).

METHODS

This was a prospective, observational study in singleton, full-term laboring participants. Doppler ultrasound PI of the UtA and UmA were obtained before and after CSE at 10 and 30 min. The primary outcome was PI at 10 min. The differences in indices were analyzed using paired t-tests orWilcoxon signed-rank tests, and mixed models were used in the exploratory analyses to assess changes over time.

RESULTS

Data were analyzed for 30 participants. Compared to baseline, there was a significant increase in mean UtA PI (Δ 27 %, P = 0.029) at 10 min, however no significant difference was observed in the UmA PI. UtA PI showed a significant increase over time (coefficient 0.05, P = 0.002), while no changes were observed in UmA PI or fetal heart rate.

CONCLUSION

Our study suggests that CSE for labor analgesia may be associated with a discrete increase in maternal UtA resistance, however, these changes are not reflected in UmA resistance in the fetus, providing reassurance that CSE with low-dose local anesthetic is a safe analgesic technique in labor.