Use of the "obstetric shock index" as an adjunct in identifying significant blood loss in patients with massive postpartum hemorrhage

Objective: To establish the normal range for the "obstetric shock index" (OSI) after birth and to determine its usefulness as an aid to estimate blood loss in postpartum hemorrhage (PPH). Methods: A retrospective case-control analysis was conducted involving pregnant women admitted to St Georges Hospital for delivery: 50 with no PPH (control group) and 50 with massive PPH (>30% loss of blood volume; case group). The OSI was calculated at 10 and 30 minutes from PPH onset. Results: Mean OSI in the control group at 10 and 30 minutes was 0.74 (range, 0.4-1.1) and 0.76 (range, 0.5-1.1), respectively. In the case group, mean OSI at 10 and 30 minutes was 0.91 (range, 0.4-1.5) and 0.90 (range, 0.5-1.4), respectively, with 64% requiring blood products. In the case group, 89% of women with an OSI of 1.1 or more at 10 minutes required transfusion; 75% with an OS! of 1.1 or more at 30 minutes required transfusion. Conclusion: We recommend that the normal OSI range should be 0.7-0.9. An OSI of more than 1 seems to be a useful adjunct in estimating blood loss in cases of massive PPH and in predicting the need for blood and blood products. (C) 2013 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.