Contributors to failed spinal anesthesia

BackgroundSpinal anesthesia is a commonly used anesthetic technique for a variety of surgical procedures. Despite its popularity and safety, failed spinal anesthesia remains an important clinical challenge, resulting in patient discomfort, need for repeated attempts, and/or conversion to general anesthesia. This systematic review compiles contemporary evidence from 2015 to 2025 on the predictors of failed spinal anesthesia.MethodsA systematic search was performed using PubMed, Embase, Cochrane Library, Web of Science, and Google Scholar. Studies published between January 2015 and May 2025 reporting contributors of failed spinal anesthesia were included. Methodological quality was evaluated using the Joanna Briggs Institute tool.ResultsTwenty-one studies comprising obstetric, orthopedic, urologic, and general surgical populations were included. Failure rates ranged from 0.9% to 25.3%. Contributors of failed spinal included low local anesthetic dose, use of isobaric solutions, provider inexperience, presence of bloody cerebrospinal fluid, absence of free cerebrospinal fluid flow, lumbar puncture at the L4-L5 interspace, high body mass index, prior spinal anesthesia exposure, emergency surgery, and multiple puncture attempts.ConclusionFailed spinal anesthesia is multifactorial and is influenced by technical, patient-related, and contextual factors. Optimization of technique, adequate dosing, enhanced provider training, and improved patient assessment may reduce failure rates.