title: One versus two venous anastomoses in microsurgical free flaps: a meta-analysis.
abstract: BACKGROUND
  Various reports suggest the augmentation of venous drainage through performing two venous anastomoses as a means of reducing the rate of thrombosis in free flap surgery. However, some suggest dual venous drainage may actually reduce venous blood flow velocity causing a potential risk for thrombosis.
  
  
  METHODS
  On the basis of the Preferred Reporting Items for Systematics Reviews and Meta-analysis statement, a systematic search was conducted using PubMed and Medline databases. A total of 12,190 articles relating to "free flaps" and "one versus two venous anastomoses" were found between January 1992 and November 2012. Of the 12,190 articles, 23 studies were included in a meta-analysis performed using STATA 11.2 (StrataCorp, College Station, TX). Studies with case control groups for both single and double venous anastomoses and clearly defined results for flap failure and venous thrombosis were included. 95% confidence interval (CI) were calculated for each study and pooled in both fixed and random-effects models for both flap failure and venous thrombosis events.
  
  
  RESULTS
  The analysis shows a significant reduction in flap failure (risk ratio, 0.64; 95% CI, 0.41-0.99; p = 0.03) and venous thrombosis (risk ratio, 0.66; 95% CI, 0.46-0.97; p = 0.047) when performing two venous anastomoses compared with one in free flap surgery.
  
  
  CONCLUSIONS
  The results show that performing two venous anastomoses is associated with a reduction in the incidence of flap failure by 36% and venous thrombosis by 34% compared with one venous anastomoses. Given that the performing of an additional venous anastomoses confers a lower risk of complication and is technically feasible, where possible two venous anastomoses should be performed in free flap procedures, however, this should be decided on a flap by flap basis.
authors: Department of Plastic and Reconstructive Surgery, Dandenong Hospital, Monash Health, Dandenong, Victoria, Australia.
authors: Iraj
authors: I
authors: Ahmadi
authors: Department of Medicine, Melbourne University, Parkville, VIC 3052, Australia.
authors: Pradyumna
authors: P
authors: Herle
authors: Department of Surgery, School of Medicine and Dentistry, James Cook University Clinical School, Douglas, Townsville, Queensland, Australia.
authors: Warren Matthew
authors: WM
authors: Rozen
authors: Department of Plastic and Reconstructive Surgery, Dandenong Hospital, Monash Health, Dandenong, Victoria, Australia.
authors: James
authors: J
authors: Leong
mesh_terms: D000714:Anastomosis, Surgical / Q000379:methods*; D058752:Free Tissue Flaps / Q000098:blood supply*; D006084:Graft Rejection / Q000517:prevention & control; D006801:Humans; D008866:Microsurgery; D020246:Venous Thrombosis / Q000517:prevention & control