Using a visual analogue pain score before vasectomy can identify men who will experience considerable pain. Warming the local anaesthetic does not reduce the pain experience during infiltration. Premedication can reduce the pain experienced.

Abstract

Introduction & Objectives: Warming local anaesthetic (LA) has been shown to decrease the pain associated with infiltration but there has been no study specifically assessing its benefit or use in vasectomy. The aim of our study was to compare the pain experience during LA infiltration using either warmed LA (37 °C) or room temperature LA (22 °C), in men undergoing bilateral vasectomy. We also assessed whether pre-medication with an anxiolytic and an analgesic decreased the pain experienced during vasectomy. Methods: A prospective, double-blinded, randomised control trial was conducted with 100 patients undergoing bilateral vasectomy during 2013/14. 5 surgeons performed the procedures using similar techniques. Each patient acted as his own control and was randomised to infiltration with warmed LA on either the first side or the second side. The contralateral side was infiltrated with room temperature LA. A nurse loaded each LA cartridge into separate McNeils non-aspirating dental syringes to ensure both patient and surgeon were blinded to the LA temperature. Patients were asked to rate their pain using the FACESTM visual analogue pain scores before the procedure (anticipated pain) and after each infiltration (first side pain, second side pain). An additional 10 patients undergoing vasectomy were pre-medicated with an anxiolytic (diazepam) and analgesic (paracetamol) and asked to rate their pain scores before and after the procedure. Wilcoxon Signed-Rank Test was used to assess statistical significance and Spearman's Rho to assess correlations. Results: Warming the LA did not significantly reduce the pain experienced during LA infiltration (P = 0.113). The second side pain was significantly worse than the first side pain (P = 0.004). First side pain was significantly less than anticipated pain (P = 0.005), however the second side pain was not significantly different to the anticipated pain (P = 0.44). A positive correlation was seen between the anticipated pain and the second side pain (R = 0.34; P = 0.0005). Subgroup analysis of a single surgeon (n = 50) also found that the second side was significantly more painful (P = 0.017) and that warming the LA did not reduce the pain experience (P = 0.33). Pre-medication reduced the overall pain experience. Conclusions: Predicting a patient's experienced pain before bilateral vasectomy using the FACESTM visual analogue pain scores may be a simple and effective way to identify men who will experience considerable pain (e.g. FACESTM ≥6) and who might benefit from pre-medication (analgesia and/or an anxiolytic) to decrease the pain experienced during their vasectomy. Warming the local anaesthetic prior to infiltration does not reduce the pain experienced by men during bilateral vasectomy.