Optimizing First-Pass Success in Subarachnoid Block: A Comprehensive Narrative Review

Abstract

Subarachnoid block (SAB), or spinal anesthesia, is a foundational technique in modern regional anesthesia, providing rapid, dense, and reliable surgical anesthesia for lower abdominal, obstetric, urological, and orthopedic surgeries. Traditionally relied upon as a landmark-guided, tactile procedure, the first-pass success (FPS) rate of SAB historically ranges from only 60% to 70% in unselected patient populations. Multiple needle passes, bony contacts, and redirections significantly escalate the risk of patient discomfort, post-dural puncture headache (PDPH), spinal hematoma, epidural vein puncture, and transient neurological symptoms. Achieving a high FPS rate has therefore evolved from a metric of clinical efficiency into a primary safety parameter.

This narrative review examines contemporary, Evidence-Based strategies designed to maximize FPS in subarachnoid blocks. It evaluates the impact of patient-related predictors of difficulty, examines advanced mechanical positioning aids and multimodal instructions, contrasts structural approaches (midline vs. paramedian), explores needle design variations, and presents the definitive role of preprocedural and real-time neuraxial ultrasound. By integrating technology with refined clinical ergonomics, anesthesia providers can transition SAB from an empirical, blind procedure into a high-precision, highly successful intervention on the first pass.