title: Timing of Chemical Thromboprophylaxis and Deep Vein Thrombosis in Major Colorectal Surgery: A Randomized Clinical Trial.
abstract: OBJECTIVE
  To identify the optimal timing of perioperative chemical thromboprophylaxis (CTP) and incidence of occult preoperative deep vein thrombosis (OP-DVT) in patients undergoing major colorectal surgery.
  
  
  BACKGROUND
  There is limited Level 1 data regarding the optimal timing of CTP in major colorectal surgery and the incidence of OP-DVT remains unclear. Both issues influence the occurrence of venous thromboembolism (VTE) and may impact Medicare reimbursement because of penalties for hospital-acquired conditions.
  
  
  METHODS
  Patients undergoing major colorectal surgery underwent preoperative lower extremity venous duplex (LEVD) immediately before surgery. Those without OP-DVT were randomized to preoperative or postoperative CTP with 5000 units of subcutaneous heparin. Patients underwent repeat LEVD in the recovery room and on postoperative day 2. Outcome measures included early (48-hrs) and overall (30-days) postoperative VTE, bleeding complications, and OP-DVT.
  
  
  RESULTS
  Eighteen patients (4.2%) had OP-DVT and were excluded. The randomized group included 376 patients (51.6% female) with mean age of 52.7 ± 17.6 years. No pulmonary embolism occurred. There was no significant difference in preoperative versus postoperative CTP with respect to early postoperative DVT [3/184 (1.6%) vs 5/192 (2.6%); P = 0.72], DVT at 30 days (1.6% vs 3.6%; P = 0.34) or bleeding complications requiring reoperation (0.5% vs 1.6%; P = 0.62).
  
  
  CONCLUSIONS
  The risk of OP-DVT is higher than that of perioperative DVT after colorectal surgery and preoperative screening LEVD should be considered to identify and treat patients at risk for pulmonary embolism. Preoperative and postoperative CTP are equally safe in protecting against VTE. CMS should account for these factors when assigning financial disincentives for perioperative VTE.
  
  
  BACKGROUND
  Clinicaltrials.gov #NCT01976988.
authors.affiliation: *Divisions of Colorectal Surgery, Cedars Sinai Medical Center, Los Angeles, CA †Department of Surgery, Cedars Sinai Medical Center, Los Angeles, CA ‡Division of Vascular Surgery, Cedars Sinai Medical Center, Los Angeles, CA §Biostatistics and Bioinformatics Research Center, Cedars Sinai Medical Center, Los Angeles, CA.
authors.forename: Karen N
authors.initials: KN
authors.lastname: Zaghiyan
authors.forename: Harry C
authors.initials: HC
authors.lastname: Sax
authors.forename: Emily
authors.initials: E
authors.lastname: Miraflor
authors.forename: David
authors.initials: D
authors.lastname: Cossman
authors.forename: Willis
authors.initials: W
authors.lastname: Wagner
authors.forename: James
authors.initials: J
authors.lastname: Mirocha
authors.forename: Bruce
authors.initials: B
authors.lastname: Gewertz
authors.forename: Phillip
authors.initials: P
authors.lastname: Fleshner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003108:Colonic Diseases / Q000150:complications / Q000601:surgery; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006493:Heparin / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D011292:Premedication; D011655:Pulmonary Embolism / Q000453:epidemiology / Q000517:prevention & control*; D012002:Rectal Diseases / Q000150:complications / Q000601:surgery; D020246:Venous Thrombosis / Q000150:complications / Q000453:epidemiology*
chemical_list: D005343:Fibrinolytic Agents; D006493:Heparin