Hypovolemic Phlebotomy in Hepatic Surgeries: Systematic Review and Updated Meta-Analysis of Blood Loss Reduction and Perioperative Outcomes.

Hepatic resection, especially in major procedures, is associated with high perioperative morbidity, primarily due to the significant risk of intraoperative hemorrhage and the consequent need for blood transfusions, factors that negatively impact clinical outcomes. Strategies to mitigate blood loss include hypovolemic phlebotomy (HP), a technique characterized by the controlled removal of a blood volume before liver transection, without immediate volume replacement, aiming to reduce central venous pressure (CVP) and consequently minimize intraoperative bleeding. Initial evidence suggests that HP may reduce the need for transfusions and improve the preservation of residual liver function, although its efficacy and safety still need to be validated in clinical studies with greater methodological robustness. This systematic review and meta-analysis aimed to assess the efficacy of hypovolemic phlebotomy in reducing blood loss during liver resections and improving perioperative outcomes. This meta-analysis was conducted following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). To build the evidence base, a search was conducted in electronic databases, including PubMed, EMBASE, and the Cochrane Library, covering publications between 2010 and 2025. The risk of bias assessment was performed using RoB 2 for randomized clinical trials (RCTs) and ROBINS-I for observational studies. Statistical analysis was conducted using Review Manager 5.4. For binary variables, risk ratio (RR) was used, while for continuous variables, mean difference (MD) was applied in outcome analysis. Cochran's Q test and Higgins' I² were used to assess heterogeneity among studies. Two RCTs and five observational studies were included, combining 3,369 patients undergoing liver surgery, with 1,759 (52.22%) in the HP group and 1,610 (47.78%) in the control group. HP was associated with a significant reduction in intraoperative blood loss (MD = -52.29; 95% CI -68.81 to -37.77; P < 0.00001). Additionally, there was a decrease in the need for intraoperative transfusion (RR = 0.27; 95% CI 0.19 - 0.38; P < 0.00001) and perioperative transfusion (RR = 0.43; 95% CI 0.28 - 0.66; P = 0.0001). Hospital length of stay showed no significant difference between groups (MD = -0.29; 95% CI -0.79 - 0.21; P = 0.26), nor did the analysis of major complications (Clavien-Dindo ≥ 3), which also did not demonstrate a statistically significant difference (RR = 0.94; 95% CI 0.72-1.24; P = 0.68). In conclusion, HP demonstrated significant outcomes in liver surgeries, particularly in reducing intraoperative blood loss and the need for intraoperative and postoperative blood transfusions. Furthermore, the technique showed no significant difference in hospital length of stay, incidence of severe complications, or other clinical outcomes. Therefore, larger randomized studies are needed to determine the real impact of HP in different surgical settings.