Fetal Bradycardia and Uterine Hyperactivity Following Subarachnoid Administration of Fentanyl During Labor

Background and Objectives Changes in uterine tone have been postulated as the cause of fetal bradycardia following subarachnoid administration of fentanyl for labor analgesia. Such a case occurred in a 20-year-old parturient with an intrauterine pressure catheter in place. Methods The patient was given intravenous terbutaline, after which contractions ceased for 20-30 minutes and then resumed. Results The patient underwent successful cesarean delivery. Retrospective analysis of the data revealed a significant increase in uterine tone and contractions following fentanyl administration. Conclusions This case supports the view that changes in uterine tone, producing a hyperdynamic contractile state and a resulting decrease in utero-placental perfusion, may explain the fetal bradycardia following subarachnoid opioid administration. Cases that do not resolve spontaneously may respond to intra-venous terbutaline.