Local anesthesia and pain perception during amniocentesis: a randomized double blind placebo-controlled trial.

Objective: To determine the effect of local anesthesia on the maternal pain perception from amniocentesis.

Methods: We conducted a randomized double blind placebo controlled trial comparing use of local anesthesia (1% lidocaine) with placebo with regards to maternal perception of pain among women undergoing genetic amniocentesis. The primary outcome was the intensity of perceived maternal pain as measured by the Visual Analogue Scale (VAS) as well a 101 point Numerical Rating Scale.

Results: Seventy six women participated in the trial. 36 (47.4%) women were randomized to lidocaine, whereas 40 (52.6%) were randomized to placebo. There were no statistically significant differences between the groups in terms of baseline sociodemographic and clinical characteristics. However, pain perception as characterized by the median 9.5 (2.1-21.0) VSA scores was significantly lower among women in the lidocaine group compared with among women in the placebo group [18.4 (12.9-31.3), P = 0.005]. Similarly the mean VSA scores was significantly lower in the lidocaine group (P = 0.02). A trend toward lower scores was also observed when maternal pain perception was measured by the Numerical Rating Scale.

Conclusion: Local anesthetic lidocaine significantly lowers maternal perceived pain during genetic amniocentesis.