Effect of topical local anaesthesia on injection pain associated with administration of sterile water injections - a randomized controlled trial

BACKGROUND: Sterile water injections can provide effective pain relief during childbirth, particularly for low back pain related to childbirth. However, the pain associated administering the injections can negatively impact women’s impressions of the procedure. It may discourage women from considering repeat doses despite the quality of analgesia experienced. Determining strategies to reduce the pain related to the administration of sterile water injections would improve the acceptability of the technique. Therefore, the aim of this study was to evaluate the effect of topical local anesthesia on the pain associated with administration of sterile water injections. METHODS: The study was designed as a multi-arm single-blind, randomized, controlled trial and 120 female healthy students were randomly divided according to one of four groups. The Intervention group received sterile water injections with topical local anesthesia. Control group 1 received sterile water injections without topical local anesthesia, control group 2 received injections of isotonic saline 0.9% with topical local anesthesia and control group 3 received injections of isotonic saline 0.9% without topical local anesthesia. Pain Immediately after the injections and subsidence in pain were recorded using a visual analogue scale. Sensations in the injection area were reported 15 min and the day after the injections. RESULTS: The main finding of this study was that local anesthesia with EMLA® reduces the pain associated with the administration of intracutaneous sterile water injections. There was a significant difference in the self-assessed pain score immediately following the injections between the control (73.3 mm) and intervention groups (50.0 mm), p = 0.001. No adverse side effects were reported. CONCLUSION: Local anesthesia with EMLA® reduces the pain associated with intracutaneous administration of sterile water injections. TRIAL REGISTRATION: The study was registered 08/07/2014 at ClinicalTrials.gov Identifier: NCT02213185.