Incidence and predictors of failed spinal anesthesia: a systematic review and meta-analysis

Spinal anesthesia is a widely used and effective regional technique, yet its failure can occur, potentially leading to patient discomfort and requiring alternative methods. Therefore, this systematic review and meta-analysis aimed to assess the pooled incidence of spinal anesthesia failure and identify associated factors.

This systematic review was prospectively registered in PROSPERO (CRD420251101582). A comprehensive literature search was conducted across PubMed, Embase, the Cochrane Library, Web of Science, and Google Scholar for studies published between January 2015 and May 2025. Using a random-effects model, we calculated the pooled incidence of failed spinal anesthesia and the pooled odds ratios (ORs) for potential predictors. Heterogeneity among studies was assessed using the I² statistic.

Twenty-one studies involving 44,790 participants were analyzed. The pooled incidence of failed spinal anesthesia was found to be 8.36% (95% CI: 6.94-9.78). Significant predictors included bar city and dose of local anesthetics, provider inexperience, bloody cerebrospinal fluid, emergency surgery, history of anesthesia, body mass index, lumbar puncture performed at the L4-L5 interspaces, and absence of free CSF flow.

The failure rate of spinal anesthesia is significant. Our findings highlight the importance of standardized techniques, optimization of local anesthetic dosage, and continuous training to reduce failures, particularly in resource-limited settings. Key associated factors considered to reduce failures.