In partial fulfilment of the requirements for the degree of Master in Medical Research.

Background: Primary postpartum hemorrhage is a leading cause of maternal mortality and morbidity worldwide. Early detection of clinical deterioration after postpartum hemorrhage (PPH) is often missed because of the masking effect of hemodynamic changes in the immediate postpartum period and underestimated blood loss. Therefore, the Shock Index (SI), which is defined as the ratio of heart rate to systolic blood pressure, and the Modifies Shock Index (MSI), which incorporates mean arterial pressure, are potential tools for assessing circulatory compromise in PPH. This study aims to evaluate the use of the Shock Index (SI) and the Modified Shock Index (MSI) in predicting adverse maternal outcomes among women experiencing primary PPH.

Method: An observational study was conducted with a total of 281 postpartum women diagnosed with primary postpartum hemorrhage at Paropakar Maternity and Women’s Hospital, Kathmandu. Ethical approval was obtained from the Institutional Review Committee of Paropakar Maternity and Women’s Hospital. Sociodemographic profiles and hemodynamic parameters, including blood pressure and heart rate, were recorded at once and two hours following the diagnosis. The Shock Index (SI) and Modified Shock Index (MSI) values were calculated based on the recorded vital parameters accordingly. Outcomes such as need for blood transfusion, surgical interventions, e.g., hemostatic sutures, condom tamponade, hysterectomy, and ICU admission were documented. Epidata 3.1 was used for the data entry, and SPSS version 21 was used for the statistical analysis. Data analysis included descriptive statistics, Wilcoxon, Signed Rank Test, Spearman correlation, ROC curve analysis, and binary logistic regression to assess predictive performance.

Results: There was a statistically significant reduction in both SI and MSI between one and two hours post-PPH (p < 0.001). Both SI and MSI show stronger correlations at one hour (P value-0.01) than at two hours (P value-0.05) for shock index and P value for modified shock index (0.01). However, MSI showed a stronger correlation with adverse outcomes than SI, with consistent predictive strength across both vaginal and cesarean deliveries. MSI may be the more reliable overall predictor at one and two hours, especially considering its incorporation of mean arterial pressure, which may better reflect perfusion status in early PPH. ROC curve analysis demonstrated that SI and MSI at one hour had good predictive value for adverse outcomes, with SI at 1 hour, the highest AUC (0.826), followed by MSI (0.799) and Estimated Blood Loss (0.806), with good sensitivity and specificity MSI maintained its value as a dynamic monitoring tool with a balanced sensitivity and specificity across both time points, Logistic regression analysis revealed MSI at one hour showed the highest predictive power (OR = 51.47, p < 0.001). In contrast, MSI at two hours remained statistically significant (OR = 32.20, p = 0.032) in comparison to SI at 1 hour (OR = 8,133.0, p < 0.001) and SI at 2 hours Odd Ratio (OR) = 343.09, p = 0.010. These results suggest that MSI is both an effective early warning marker and a reliable tool for continued risk assessment in the postpartum period at MSI demonstrated more consistent performance across both time points.

Conclusion: Both Shock Index (SI) and Modified Shock Index (MSI) are valuable predictors of adverse maternal outcomes in primary postpartum hemorrhage (PPH), with significant changes observed between one and two hours postpartum. MSI showed a stronger and more consistent predictive ability across different time points and modes of delivery. MSI at one hour had the highest predictive value (OR = 51.47, p < 0.001), and this significance persisted at two hours. Due to its inclusion of mean arterial pressure and stable performance, MSI appears to be a more reliable early warning and monitoring tool for guiding clinical management in PPH.

Key words: Adverse outcome, Modified shock index, Postpartum hemorrhage, Shock index.