Entonox analgesia for prostatic biopsy

We performed a prospective randomised double-blind study to evaluate the efficacy of Entonox (nitrous oxide) as an analgesic for trans-rectal ultrasound (TRUS) and prostate biopsy. A total of 50 patients breathed either Entonox or air during sextant prostatic biopsies all of which were performed by the same surgeon. The degree of pain experienced was recorded on a 100 mm visual analogue pain scale. A total of 17 further patients were excluded from the study because they wished to drive home after TRUS. Most patients breathing air experienced moderate pain (median pain score 34), whereas those breathing Entonox experienced minimal pain (median pain score 11). Two patients who used Entonox and one breathing air experienced severe pain. We conclude that patients undergoing prostate biopsy without analgesia experience moderate pain and this can be reduced significantly by using Entonox.