The benefit of a perianal block as an adjunct to general or regional anaesthesia is debated. This RCT aimed to compare pain at 24 h and up to 14 days after proctological surgery in patients with and without a perianal block.
Between January 2018 and April 2019, patients were allocated to receive a perianal block with ropivacaine or placebo as an adjunct to anaesthesia. Patients, surgeons and assessors were blinded. The primary outcome was pain measured on a numerical rating scale (NRS) after 24 h. Secondary outcomes were need for rescue analgesia, and pain after 1, 2, 3, 6 and 12 h. The mean, rest and maximum NRS scores were measured for 14 days.
A total of 138 patients were included, of whom 46 and 44 received general anaesthesia with or without ropivacaine respectively, and 23 and 25 received spinal anaesthesia with or without ropivacaine respectively (P = 0·858). The mean NRS score differed significantly at 24 h (mean(s.d.) 1·1(0·1) versus 2·3(0·2); P < 0·001), but not at 1 h (1·4(0·2) versus 2·2(0·3); P = 0·051). The NRS score was lower with use of ropivacaine at 2 h (1·0(0·2) versus 1·6(0·2); P = 0·045), 3 h (0·9(0·2) versus 1·5(0·2); P = 0·022), 6 h (1·1(0·2) versus 1·8(0·2); P = 0·042) and 12 h (1·2(0·2) versus 1·8(0·2); P = 0·034). The use of oral morphine equivalents was 10·2(1·4) and 16·6(2·5) mg with and without ropivacaine respectively (P = 0·028). The mean and maximum NRS scores within 14 days were lower when ropivacaine was used (95 per cent c.i. for difference 0·14 to 0·49 (P = 0·002) and 0·39 to 0·63 (P < 0·001) respectively). There was no injection-associated morbidity.
Perianal block as an adjunct to general or regional anaesthesia should be recommended for proctological surgery. It yields a reduction in pain, a reduced need for opioids, and a faster recovery with minimal risk of adverse events. Registration number: NCT03405922 ( http://www.clinicaltrials.gov).

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