Testing of Pre-Operative Peripheral Nerve Blocks in Randomised Controlled Trials: A Scoping Review.

Abstract

<h4>Background</h4>Peripheral nerve blocks are widely used for anaesthesia in upper and lower limb surgery, but the methods used to assess their success vary substantially. This scoping review examined contemporary research practises and the extent to which trials report on peripheral nerve block evaluation.<h4>Methods</h4>A search was conducted on PubMed for randomised controlled trials published between 2014 and 2025 in anaesthesia journals, involving pre-operative peripheral nerve blocks in adults undergoing limb surgery. Two independent authors screened and extracted data for each trial. Outcomes included the proportion of trials that reported block testing, described test methods, defined successful blocks, and reported success rates.<h4>Results</h4>Of 284 trials included, 215 (76%, 95% CI 71%-81%) reported testing blocks, and 210 (74%, 95% CI 69%-79%) described the test methods. Of the 215 trials reporting testing, 204 used sensory assessments (95%, 95% CI 91%-97%) and 157 used motor assessments (73%, 95% CI 67%-79%). Success criteria were defined in 164/284 trials (58%, 95% CI 52%-63%), and the same number reported success rates. In the 164 trials reporting on peripheral nerve block success, the median success rate was 98% (IQR 92%-100%).<h4>Conclusion</h4>This scoping review investigated contemporary practise in test methodology reporting in RCTs involving PNBs. We found that although most trials do report testing PNBs, about one in four did not. Furthermore, approximately two in five trials did not define what constituted a successful block or report PNB success rates. Lack of consistent and transparent test methodology poses challenges when comparing trials and performing meta-analyses, and in translating trial findings into clinical practise. This scoping review exposes a methodological blind spot in regional anaesthesia research. Despite widespread use of peripheral nerve blocks, a substantial proportion of randomised trials fail to report testing methods, success definitions, or handling of failed blocks. Such omissions undermine interpretability, comparability, and clinical translation, and strengthen the case for standardised reporting of regional anaesthesia assessment in future trials.