Abnormal obstetric shock index and associated factors among immediate postpartum women following vaginal delivery at a tertiary hospital in southwestern Uganda

Background Early recognition of haemodynamic instability after birth and prompt interventions are necessary to reduce adverse maternal outcomes due to postpartum haemorrhage. Obstetric shock Index (OSI) has been recommended as a simple, accurate, reliable, and low-cost early diagnostic measure that identifies hemodynamically unstable women. Objectives We determined the prevalence of abnormal obstetric shock index and associated factors among women in the immediate postpartum period following vaginal delivery at Mbarara Regional Referral Hospital (MRRH) in southwestern Uganda. Methods We conducted a cross-sectional study at the labour suite and postnatal ward of MRRH from January 2022 to April 2022. We systematically sampled women who had delivered vaginally, and measured their blood pressures and pulse rates at 1 h postpartum. We excluded mothers with hypertensive disorders of pregnancy. Sociodemographic, medical and obstetric data were obtained through interviewer-administered questionnaires. The prevalence of abnormal OSI was the proportion of participants with an OSI ≥ 0.9 (calculated as the pulse rate divided by the systolic BP). Logistic regression analysis was used to determine associations between abnormal OSI and independent variables. Results We enrolled 427 women with a mean age of 25.66 ± 5.30 years. Of these, 83 (19.44%), 95% CI (15.79–23.52) had an abnormal obstetric shock index. Being referred [aPR 1.94, 95% CI (1.31–2.88), p = 0.001], having had antepartum haemorrhage [aPR 2.63, 95% CI (1.26–5.73), p = 0.010] and having a visually estimated blood loss > 200 mls [aPR 1.59, 95% CI (1.08–2.33), p = 0.018] were significantly associated with abnormal OSI. Conclusion Approximately one in every five women who delivered vaginally at MRRH during the study period had an abnormal OSI. We recommend that clinicians have a high index of suspicion for haemodynamic instability among women in the immediate postpartum period. Mothers who are referred in from other facilities, those that get antepartum haemorrhage and those with estimated blood loss > 200mls should be prioritized for close monitoring. It should be noted that the study was not powered to study the factors associated with AOSI and therefore the analysis for factors associated should be considered exploratory.