Revised shock index for clinical decision-making and optimal referral timing in managing severe postpartum hemorrhage during cesarean section: a retrospective case-control study

Objective ​ To evaluate the predictive value of revised shock index for severe postpartum hemorrhage (PPH) during cesarean section.​Methods ​ This case-control study enrolled women undergoing cesarean delivery at our institution from September 2018 to March 2024. The PPH group (n=231) comprised patients with intraoperative blood loss ≥1 000 ml, while controls (n=231) without PPH were randomly selected. Comparative analysis of clinical characteristics identified PPH risk factors. Receiver operating characteristic (ROC) curves assessed traditional and various revised shock indices' predictive performance for: (1) blood loss ≥1 000 ml, (2) transfusion requirement, (3) hysterectomy, and (4) ICU admission. Correlation analyses examined relationships between peak shock index (peak SI), delta shock index (ΔSI), delta hemoglobin (delta Hb), and intraoperative blood loss.​Results ​ For predicting blood loss ≥1 000 ml, transfusion, and hysterectomy, ΔSI demonstrated optimal area under curve (AUC) values: 0.727 (95%CI: 0.681-0.772), 0.741 (95%CI: 0.696-0.786), and 0.812 (95%CI: 0.710-0.915), respectively. Peak SI showed highest AUC (0.804, 95%CI: 0.706-0.902) for ICU admission prediction. Significant correlations were observed: moderate positive between peak SI/ΔSI and blood loss (r=0.413 and 0.452), moderate negative between delta Hb and blood loss (r=-0.505) (all P<0.001).​Conclusion ​ This systematic evaluation confirms ΔSI and peak SI as accurate predictors for adverse outcomes in cesarean-related PPH, providing objective evidence for early recognition, targeted intervention, and timely referral.