Diagnostic accuracy of shock index as screening tool for primary postpartum haemorrhage after caesarean section among women at Kawempe national referral hospital

Abstract

Introduction: Postpartum haemorrhage is among the leading cause of maternal mortality globally and in sub-Saharan Africa. The risk of PPH is significantly increased following caesarean section compared to vaginal delivery. In Uganda, the caesarean section rates have remained high in referral centres despite the low health worker to patient ratio. The early identification of a patient at risk of PPH is crucial for better prognostic outcomes. The African maternal early warning score, a tool that is recommended for this purpose has four parameters; making it cumbersome, and requiring many resources, therefore, rarely used. The shock index( ratio of the pulse to systolic pressure) is a quicker and more objective assessment tool in assessing the risk of deterioration as may occur in PPH, before apparent clinical deterioration. The diagnostic accuracy of shock index in a Ugandan setting is not known Objective: To determine the sensitivity and specificity, positive and negative predictive values of shock index in the diagnosis of primary postpartum haemorrhage after caesarean section among women delivering at Kawempe National Referral Hospital. Methods: A cross-sectional study design was used. The study was conducted in Kawempe National Referral Hospital labour ward, antenatal ward, post natal ward and high dependence unit between the period of 1st January 2021 and 31st May 2021. Women who were delivered by caesarean section and consented to participate in the study during the study period were recruited. A sample size of 594 was determined using formulae by Buderer. A consecutive sampling technique was used. We approached 650 participants; while 591 we fit for analysis. All participants were subjected to determination of shock index at different intervals and the change in haematocrit as the gold standard for post-partum haemorrhage. Results: The sensitivity and specificity of the shock index at 2 hours were 40.0 and 82.8 per cent respectively at a threshold of 0.8. The sensitivity and specificity were 70.0 and 54.6 per cent after 24 hours when the shock index threshold of 0.7 was used. The PPV and NPV were 3.8 and 98.3 per cent at 2 hours respectively while 2.6 and 99.1 per cent at 24 hours. Conclusion: The shock index had poor diagnostic accuracy for diagnosing primary postpartum haemorrhage after caesarean section.