Shock Index and Modified Shock Index as Predictors of Adverse Maternal Outcomes in Primary Postpartum Hemorrhage

Abstract

Background: Postpartum hemorrhage is a leading cause of maternal morbidity and mortality, particularly in developing countries like Nepal. Early identification of women at risk is vital but traditional methods are sometimes subjective. Simple objective tools are of high importance in times of need. This study aimed to evaluate and compare the predictive performance of the Shock Index and Modified Shock Index for adverse maternal outcomes after primary postpartum hemorrhage.
Methods: A hospital based cross sectional study was conducted at a tertiary maternity hospital in Nepal. The study included 281 women diagnosed with primary postpartum hemorrhage. Heart rate, systolic blood pressure and mean arterial pressure were recorded at 1 and 2 hours postpartum. Shock Index and MSI were calculated. The adverse maternal outcomes such as including blood transfusion, surgical interventions or intensive care unit admissions were analyzed. The predictive ability of Shock Index and Modified Shock Index was analyzed using Receiver Operating Characteristic curve analysis.
Results: Both Shock Index and Modified Shock Index were significant predictors of adverse maternal outcomes. The single best predictor was identified as Shock Index as measured at 1 hour in women who underwent cesarean delivery, with an Area Under the Curve of 0.811 (95% CI: 0.754–0.868). For vaginal deliveries at 1 hour, Shock Index and Modified Shock Index performed similarly (Area Under Curve 0.777 and 0.776, respectively). Predictive ability decreased at the 2 hour mark, especially for patients post-cesarean delivery. Logistic regression confirmed that cesarean delivery and Shock Index at 1 hour were strong and independent predictors of the adverse outcomes.
Conclusions: The Shock Index is a simple and effective tool for the early detection of increased risk of adverse outcomes from postpartum hemorrhage. Modified Shock Index in particular showed greater overall predictability. Its routine implementation in postpartum monitoring, primarily in low-resource settings can significantly aid the triage and facilitate early life saving interventions.
Keywords: maternal mortality; modified shock index; postpartum hemorrhage; shock index.