One Versus 2 Venous Anastomoses in Free Flap Surgery: A Systematic Review and Meta-Analysis.

The necessity of a second venous anastomosis in free flap surgery is controversial. The purpose of this systematic review is to determine whether venous flap failure and reoperation rates are lower when 2 venous anastomoses are performed. The secondary objective is to determine whether venous flap failure and reoperation rates are lower when the 2 veins are from 2 different drainage systems.A comprehensive search of the literature identified relevant studies. Investigators independently extracted data on rates of flap failure and reoperation secondary to venous congestion. A meta-analysis was performed; odds ratios (ORs) were pooled using a random-effects model and 95% confidence intervals (CIs).Of 18 190 studies identified, 15 were included for analysis. The mean sample size was 287 patients (minimum = 102, maximum = 564). No statistically significant difference in venous flap failure was found when comparing 1 versus 2 venous anastomoses (OR: 1.35; 95% CI: 0.46-3.93). A significant decrease in reoperation rate due to venous congestion was shown (OR: 3.03; 95% CI: 1.64-5.58). The results favor using 2 veins from 2 different systems over veins from the same system (OR: 0.16; 95% CI: 0.02-1.27).There is low-quality evidence suggesting that the use of 2 venous anastomoses will lower the rate of reoperation due to venous congestion. There are insufficient data published to meaningfully compare outcomes of flaps with 2 venous anastomoses from different systems to flaps with anastomoses from the same system.