Performance of Shock Index as a predictor of severe postpartum hemorrhage following cesarean section under spinal anesthesia: a retrospective cohort study.

BACKGROUND

An early diagnosis of a postpartum hemorrhage (PPH) can be challenging. The Shock Index (SI), the ratio of heart rate to systolic blood pressure, appears to be a useful indicator for the early diagnosis of severe PPH after vaginal delivery. Our primary aim was to evaluate if the SI has a predictive value for severe PPH following cesarean section (C-section) under spinal anesthesia (SA) and its best predictive threshold.

METHODS

Retrospective single-center trial including women scheduled for C-section under SA with prevention of maternal hypotension by phenylephrine, and complicated by PPH between 2019 and 2021. Women were divided into two groups: non-severe PPH (blood loss <1000 mL) versus severe PPH (blood loss ≥1000 mL). SI was calculated and compared between the groups at four different time points: T0: prior to C-section; T1: at incision; T2: 15 minutes from start of PPH; T3: end of PPH management. Using receiver operating characteristic curve, we calculated the area under the curve (AUC) and the best diagnostic threshold (sensitivity and specificity) for predicting severe PPH.

RESULTS

Overall, 129 patients were included, 26 (20.2%) with severe PPH. Median SI was significantly higher at T2 in the severe PPH group (1.14 (1.10-1.25) versus 1.0 (0.85-1.10), P<0.001), but not at other times of management. An SI value of ≥1.17 was the best threshold with an AUC of 0.81 (95% CI 0.72 to 0.90), a sensitivity of 0.42 and a specificity of 0.88.

CONCLUSIONS

SI may be an early indicator of severe PPH during C-section under SA.