title: Maintenance of warfarin anticoagulation for patients undergoing vitreoretinal surgery.
abstract: OBJECTIVE
  To evaluate the risk of hemorrhagic complications associated with vitreoretinal surgery in patients whose warfarin sodium therapy was continued throughout the surgical period.
  
  
  METHODS
  A review of 1737 records of patients undergoing pars plana vitrectomy was conducted. Inclusion criteria included patients receiving warfarin therapy whose international normalized ratios (INRs) were elevated above normal values on the day of surgery. Intraoperative and postoperative hemorrhagic complications were documented.
  
  
  RESULTS
  Fifty-four patients underwent 57 vitreoretinal surgical procedures with warfarin therapy and were divided into groups as follows: group S with INRs of 1.20 to 1.49, values considered subtherapeutic; group B with INRs of 1.50 to 1.99, values considered borderline therapeutic; group T with INRs of 2.00 to 2.49, values considered therapeutic; and group HT with INRs of 2.50 or greater, values considered highly therapeutic. No patients experienced anesthesia-related or intraoperative hemorrhagic complications. Two (7.7%) of 26 eyes in group S and 2 (16.7%) of 12 eyes in group HT experienced postoperative hemorrhages. All of the patients with vitreous hemorrhages had spontaneous clearing without additional treatment.
  
  
  CONCLUSIONS
  Many patients may safely undergo vitreoretinal surgery while maintaining therapeutic levels of warfarin anticoagulation. We experienced no intraoperative hemorrhagic complications; the 4 postoperative complications resolved spontaneously without persistent visual sequelae or the need for supplemental surgery.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO 63144, USA.
authors.forename: Pouya N
authors.initials: PN
authors.lastname: Dayani
authors.forename: M Gilbert
authors.initials: MG
authors.lastname: Grand
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D007431:Intraoperative Complications; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D011183:Postoperative Complications; D011517:Prothrombin Time; D012164:Retinal Diseases / Q000601:surgery*; D012189:Retrospective Studies; D012307:Risk Factors; D014821:Vitrectomy; D014823:Vitreous Hemorrhage / Q000139:chemically induced; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014859:Warfarin