Objective To investigate the induction factors of hypotension during cesarean section for perilous placenta previa under combined spinal-epidural anesthesia (CSEA) and to construct a nomogram prediction model.

Methods A total of 130 parturients who underwent cesarean section for perilous placenta previa under CSEA from January 2020 to December 2023 in Yulin Maternity and Child Healthcare Hospital were selected as study subjects. A self-designed general information questionnaire was used to investigate the basic information and the occurrence of hypotension of the subjects. According to the occurrence of intraoperative hypotension, the patients were divided into hypotension group (47 cases) and non-hypotension group (83 cases). Univariate analysis was performed on the general information of the two groups, and multivariate Logistic regression analysis was used to explore the induction factors of intraoperative hypotension.

Results Univariate analysis showed that there were statistically significant differences in body mass index, anesthesia level, presence of multiple pregnancy, preoperative systolic blood pressure, operative time, and the occurrence of Bezold-Jarisch reflex between the two groups (P < 0.05). Multivariate Logistic regression analysis revealed that body mass index≥ 24 kg/m², anesthesia level was in the eighth thoracic vertebra(T8) or above, multiple pregnancy, preoperative systolic blood pressure < 90 mmHg, operative time >1.5 h, and the occurrence of Bezold-Jarisch reflex were independent risk factors for hypotension during cesarean section for perilous placenta previa under CSEA (P < 0.05). A regression equation for the induction factors of hypotension during cesarean section for perilous placenta previa under CSEA was constructed: Logit(P)=-23.211+1.079×(body mass index ≥ 24 kg/m²)+1.101×anesthesia level (≥T8)+3.193×multiple pregnancy+2.214×preoperative systolic blood pressure (< 90 mmHg)+4.606×operative time (>1.5 h)+2.011×occurrence of Bezold-Jarisch reflex. The nomogram showed high discrimination and accuracy for patients with preoperative systolic blood pressure < 90 mmHg. After 1, 000 times of Bootstrap resampling for the nomogram model, a calibration curve was obtained, and the consistency index was calculated as 0.850, indicating good calibration of the nomogram model. The receiver operating characteristic (ROC) curve was plotted, with an area under the curve of 0.896 and 95% confidence interval of 0.802 to 0.956, suggesting good predictive performance.

Conclusion Body mass index ≥24 kg/m², anesthesia level ≥ T8, multiple pregnancy, preoperative systolic blood pressure < 90 mmHg, operative time >1.5 h, and the occurrence of Bezold-Jarisch reflex are induction factors for hypotension during cesarean section for perilous placenta previa under CSEA.