Accuracy of visual intraoperative estimated blood loss during caesarean section performed under subarachnoid block
Background: Postpartum haemorrhage (PPH) is a leading cause of maternal mortality worldwide. Inaccurate intraoperative estimated blood loss (EBL) may lead to delayed or unnecessary blood transfusion, resulting in dire consequences. This study assessed the accuracy of visually EBL during Caesarean section (CS) performed under subarachnoid block (SAB).
Methods: Fifty-two consecutive consenting women of American Society of Anesthesiologists (ASA) physical status class II, aged 18 to 45 years scheduled for elective CS under SAB that fulfilled the inclusion criteria were recruited. EBL was visually assessed during skin closure by the attending physician anaesthetist. The initial and final haematocrit values were taken by the principal investigator pre- and postoperatively respectively using Mission® Hb Haemoglobin Testing System. The Actual blood loss (ABL) was calculated using Modified Gross Formula and compared with the visually EBL.
Results: There was a statistically significant difference between the mean EBL (522 ml ± 146 ml) and the mean ABL (821ml ± 615 ml); p = 0.001. EBL was underestimated in 33 (63.5%) patients and overestimated in 19 (36.5%). EBL overestimation occurred more when the ABL was ≤ 500 ml, and underestimation occurred more when ABL was within 501 - 1000 ml. Gross underestimation of blood loss was noticed when ABL was > 1000 ml; (p = 0.001). Within 20% error margin, blood loss was correctly estimated in 7 (13.5%), underestimated in 30 (57.7%) and overestimated in 15 (28.8%) patients; p = 0.001.
Conclusion: Visually EBL during CS performed under SAB was inaccurate especially at extremes of blood loss.