title: A Systematic Review and Meta-Analysis of Double Venous Anastomosis in Free Flaps.
abstract: BACKGROUND
  Venous problems are the most frequent causes of flap failure and surgical revision in free flap surgery. Double venous anastomosis can be used to improve flap drainage, but this procedure has not been adopted universally and remains controversial. The authors evaluated the benefits of double venous anastomosis in terms of venous thrombosis rate, surgical revision of flaps, and flap failure rate.
  
  
  METHODS
  A systematic literature review was conducted searching the MEDLINE, PubMed Central, Cochrane, and Embase databases for articles published between 1996 and July of 2014. Data analysis consisted of evaluating the pooled relative risks of single and double venous anastomoses in fixed and random-effects models.
  
  
  RESULTS
  The final analysis included 27 articles involving 6842 flaps. The overall success rate was 97.48 percent. Single venous anastomosis was performed in 4591 flaps versus two anastomoses in 2251 flaps. The failure rate was 3.1 percent for single anastomosis versus 1.3 percent for double anastomosis (OR, 0.511; 95 percent CI, 0.349 to 0.747; p = 0.001). The respective thrombosis rates were 3.1 percent versus 2.3 percent (OR, 0.586; 95 percent CI, 0.390 to 0.880; p = 0.010). In addition, more single venous anastomoses were revised: 7.7 percent versus 6 percent (OR, 0.601; 95 percent CI, 0.469 to 0.770; p < 0.0001). Stratified analysis by flap type did not show any significant differences.
  
  
  CONCLUSIONS
  Although the physiologic mechanisms remain poorly understood, the data strongly support double venous anastomosis, considering the reduction in flap failure, microsurgical venous thrombosis, and surgical revision. The authors recommend double anastomosis whenever it is feasible in free flap surgery.
authors.affiliation: Toulouse, Montpellier, Lyon, and Rennes, France From the Department of Plastic and Reconstructive Surgery, Rangueil University Hospital; the Departments of Plastic and Reconstructive Surgery and Biostatistics and Medical Information, Lapeyronie University Hospital; the Department of Plastic and Reconstructive Surgery, Edouard Herriot University Hospital; the Department of Plastic, Reconstructive, and Aesthetic Surgery, Hospital Sud, University of Rennes 1; and the Biostatistic Unit, Institut Universitaire du Cancer Toulouse.
authors.forename: Samuel
authors.initials: S
authors.lastname: Riot
authors.forename: Christian
authors.initials: C
authors.lastname: Herlin
authors.forename: Ali
authors.initials: A
authors.lastname: Mojallal
authors.forename: Ignacio
authors.initials: I
authors.lastname: Garrido
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bertheuil
authors.forename: Thomas
authors.initials: T
authors.lastname: Filleron
authors.forename: Serge
authors.initials: S
authors.lastname: Somda
authors.forename: Jean Louis
authors.initials: JL
authors.lastname: Grolleau
authors.forename: Raphael
authors.initials: R
authors.lastname: Lopez
authors.forename: Benoit
authors.initials: B
authors.lastname: Chaput
mesh_terms: D000714:Anastomosis, Surgical; D058752:Free Tissue Flaps / Q000098:blood supply* / Q000601:surgery*; D006801:Humans; D008866:Microsurgery; D011183:Postoperative Complications / Q000517:prevention & control*; D014656:Vascular Surgical Procedures / Q000379:methods; D014680:Veins / Q000601:surgery