Is double venous anastomosis better than single venous anastomosis in head and neck reconstruction with free flaps? A systematic review and meta-analysis.

Venous complications are the main cause of flap loss and revision in free flap surgery. Although a second venous anastomosis has been proposed to improve drainage, its efficacy remains debated. The aim of this review was to assess whether performing two venous anastomoses is associated with a reduced risk of flap loss. Secondary objectives were the evaluation of venous compromise, revision rates, and outcomes by flap type. This systematic review was conducted in accordance with the PRISMA criteria, utilizing the Web of Science, PubMed Central, and Cochrane Library databases. Heterogeneity was assessed using a fixed- or random-effects model depending on the outcome. Overall, 37 articles involving 9996 flaps were included in the study (single venous anastomosis (SVA), 5274 flaps; double venous anastomosis (DVA), 4722 flaps). The overall success rate was 97.09%. The odds of flap loss were significantly higher in the SVA group (odds ratio 1.49, 95% confidence interval 1.07-1.84; P = 0.018). Venous congestion and surgical revision rates also favoured the DVA group. Subgroup analyses and meta-regression did not demonstrate a significant effect of flap type. The results of this systematic review and meta-analysis suggest that DVA may reduce flap loss, although the magnitude of the effect was modest and of uncertain clinical relevance. However, most included studies were retrospective, and the pooled estimates were based on unadjusted data, which limits the strength of the conclusions.