Possible underestimation of blood loss during laparoscopic hepatectomy.

Background: Previous studies have documented potential advantages of laparoscopic hepatectomy in decreasing blood loss compared with open surgery. This study aimed to compare intraoperative blood loss estimated using four different methods in open versus laparoscopic hepatectomy. Methods: Patients undergoing liver resection between 2014 and 2017 were evaluated prospectively, differentiating between the laparoscopic and open approach. Groups were compared using univariable and multivariable analyses. Intraoperative blood loss was estimated using three formulas based on the postoperative decreases in haematocrit, haemoglobin or red blood cell volume, and using the conventional method of the sum of suction fluid amounts and gauze weight. In addition, blood loss per hepatic transection area was calculated to compare groups. Results: Some 125 patients who underwent hepatectomy were selected, including 56 open hepatectomies and 69 laparoscopic liver resections. Intraoperative blood loss per hepatic transection area estimated by the conventional method was significantly less in the laparoscopic than the open group (3.6 (range 0.2-50.0) versus 6.6 (1.2-82.5) ml/cm(2) respectively; P<0.001). In contrast, there were no significant differences between groups in blood loss estimated based on the decrease in haematocrit (12.9 (0-65.2) versus 8.1 (0-123.7) ml/cm(2); P = 0.818), haemoglobin or red blood cell volume. Blood loss estimation using three formulas showed significant linear correlations with the blood loss estimated by the conventional method in the open group (r(s)=0.758 to 0.762), but not in the laparoscopic group (r(s)=-0.019 to 0.031). Conclusion: The conventional method of calculating blood loss in laparoscopic hepatectomy can underestimate losses.