Timing of Chemical Thromboprophylaxis and Deep Vein Thrombosis in Major Colorectal Surgery: A Randomized Clinical Trial

Ann Surg. 2016 Oct;264(4):632-9. doi: 10.1097/SLA.0000000000001856.


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.

Trial registration: Clinicaltrials.gov #NCT01976988.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Colonic Diseases / complications
  • Colonic Diseases / surgery
  • Female
  • Fibrinolytic Agents / therapeutic use*
  • Heparin / therapeutic use*
  • Humans
  • Male
  • Middle Aged
  • Postoperative Complications / epidemiology
  • Postoperative Complications / prevention & control*
  • Premedication*
  • Pulmonary Embolism / epidemiology
  • Pulmonary Embolism / prevention & control*
  • Rectal Diseases / complications
  • Rectal Diseases / surgery
  • Venous Thrombosis / complications
  • Venous Thrombosis / epidemiology*


  • Fibrinolytic Agents
  • Heparin

Associated data

  • ClinicalTrials.gov/NCT01976988