Inadequate neuraxial anesthesia during cesarean delivery: incidence and predictors in a large retrospective contemporary cohort

Objective Spinal anesthesia is the preferred anesthetic technique for cesarean delivery because of its favorable maternal and neonatal safety profile. Despite its widespread use, inadequate neuraxial anesthesia remains an important clinical problem that may result in intraoperative pain, supplemental pain relief, or conversion to general anesthesia. Previous studies have shown inconsistent incidence rates and unreliable predictors of failed spinal anesthesia. This study aimed to determine the incidence of inadequate spinal anesthesia during cesarean delivery and to identify patient- and procedure-related factors associated with block inadequacy. Methods This retrospective cohort study included all adult patients who underwent cesarean delivery under planned spinal anesthesia at a tertiary university hospital between January 2020 and January 2026. Inadequate spinal anesthesia was defined as the combination of partial and total failure of spinal block. Demographic, obstetric, anesthetic, and surgical variables were evaluated. Multivariable logistic regression analysis was performed to identify independent predictors of inadequate spinal anesthesia. Results A total of 3,382 cesarean deliveries performed under spinal anesthesia were analyzed. Adequate spinal anesthesia was achieved in 3,216 patients (95.1%). Inadequate spinal anesthesia occurred in 166 patients (4.9%), including 135 partial failures (4.0%) and 31 total failures (0.9%). Increasing age and higher educational level were associated with lower odds of inadequate spinal anesthesia, whereas postpartum sterilization and surgical adhesions were independently associated with higher odds of inadequate spinal anesthesia. Conclusions Although spinal anesthesia provided effective surgical anesthesia in the vast majority of cesarean deliveries, inadequate neuraxial block remained clinically relevant. Both patient-related and surgical factors were associated with an increased risk of block inadequacy. Identification of high-risk patients may facilitate individualized anesthetic planning and improve maternal intraoperative experience.