Outcomes After Intraoperative Hypovolemic Phlebotomy in Patients Undergoing Liver Surgery: A Meta-Analysis

The risk of blood loss in liver surgery remains a recent concern. Recent investigations have shown that intraoperative hypovolemic phlebotomy (HP) is effective at reducing blood loss and transfusions during liver surgery. In this meta-analysis, we seek to assess the effects of HP on patients undergoing liver surgery.

Electronic databases, PubMed, Embase, and Web of Science, were searched from inception to January 2025, with an update in November 2025. Our eligibility criteria included randomized controlled trials (RCTs) or observational studies comparing HP to standard care in patients undergoing liver surgery. A random effects model was used for analysis pooling the mean differences (MD) and risk ratios (RRs) with corresponding 95% confidence intervals (CIs).

A total of 13 studies, with 4577 patients, were analyzed. Compared with the control group, the use of HP was associated with a lower incidence of perioperative RBC transfusion (RR: 0.55, 95% CI: [0.46 to 0.67], p < 0.0001, and I² = 18.50%). Subgroup analyses showed consistent results across different subgroups according to the type of surgery: liver resection subgroup (RR: 0.57, 95% CI: [0.43 to 0.75], I² = 27.87%) and liver transplantation subgroup (RR: 0.52, 95% CI: [0.42 to 0.63], I² = 18.74%) (p_interaction = 0.85), and study design: RCTs subgroup (RR: 0.65, 95% CI: [0.44 to 0.96], I² = 14.15%) and the observational cohort studies subgroup (RR: 0.52, 95% CI: [0.40 to 0.67], I² = 34.34%) (p_interaction = 0.34). Similarly, the use of HP significantly reduced the intraoperative RBC transfusions rate (RR: 0.46, 95% CI: [0.31 to 0.68], p < 0.0001), postoperative RBC transfusions rate (RR: 0.60, 95% CI: [0.44 to 0.82], p < 0.0001), and estimated blood loss (MD: -237 mL, 95% CI: [-383.43 to -90.98], p < 0.001) compared with the control group. Secondary and safety outcomes, such as central venous pressure, hospital stay duration, and overall complications, were comparable between the two groups. The GRADE assessment indicated that the certainty of evidence for perioperative RBC transfusions was high in the RCTs subgroup but low in the observational subgroup.

Among patients undergoing liver surgery, the use of HP was associated with a lower blood transfusion rate and blood loss, while maintaining an acceptable safety profile. Further large clinical trials are necessary to clarify the exact mechanism involved.