Spacing the injection interval with paracervical block: a randomized study.

To test the hypothesis that spacing the injection interval by 10 minutes would reduce the incidence of post-paracervical block bradycardia, 42 healthy subjects at low risk with normal fetal heart rate (FHR) patterns were included in a randomized trial. Twenty patients were given a conventional paracervical block (ie, almost simultaneous injection of the 2 sides), whereas 22 patients were given the second injection after a 10-minute interval. All patients were laterally positioned for 30 minutes before and 60 minutes after administration of the paracervical block. There were no cases of post-paracervical block bradycardia in either group, but a decrease in the baseline FHR of 5 beats per minute or more occurred in one half of each group. Both groups experienced significant decreases in the mean FHR. The authors conclude that patient selection and perhaps lateral positioning are more important than is spacing the injection interval. Furthermore, in properly selected subjects paracervical block offers simple, effective, and safe analgesia.