Prospective Study on Preoperative Versus Postoperative Venous Thromboprophylaxis in Patients Undergoing Major Colorectal Surgery

PROSPECTIVE STUDY ON PREOPERATIVE VERSUS POSTOPERATIVE VENOUS THROMBOPROPHYLAXIS IN PATIENTS UNDERGOING MAJOR COLORECTAL SURGERY

Patients undergoing major colorectal surgery are at increased risk for VTE (deep venous thrombosis) compared with patients undergoing other general surgical procedures (Bergqvist et al. Dis. Col. Rectum. 2006; 49: 1620-1628.)

The reported incidence of symptomatic VTE after colorectal surgery is approximately 4% (Monn, F. et al. JACS. 216; 2013: 395-401). However, the reported incidence of VTE after colorectal surgery in prospectively followed patients managed with perioperative venous thromboprophylaxis undergoing screening venography prior to hospital discharge ranges from 9 to 20% (Bergovist et al. NEJM 346; 2002: 975-980; McLeod et al. Ann. Surg. 233; 2000: 438-444; ENOXACAN Study group. Brit. J. Surg. 84; 1997: 1099-1103.

The Surgical Care Improvement Project (SCIP) and the American College of Chest Physician (ACCP) guidelines recommend that venous thromboprophylaxis be initiated within 24 hours of surgery. However, it is believed that deep venous thrombosis occurs during surgery, rather than in the postoperative period, justifying preoperative initiation of venous thromboprophylaxis. This practice is accompanied with a theoretically higher risk of bleeding complications.

Currently there is no consensus on the precise timing of VTE prophylaxis after major colorectal surgery, as demonstrated by the vague guidelines established by the ACCP and SCIP. Current studies on VTE prophylaxis report preoperative initiation of VTE prophylaxis. However, majority of surgeons at our institution begin heparin postoperatively given concern for bleeding complications with preoperative dosing of heparin.

The purpose of this study is to prospectively evaluate the incidence of VTE and major bleeding complications in patients undergoing major colorectal surgery who are treated with preoperative or postoperative venous thromboprophylaxis and to help establish more stringent guidelines on the optimal timing of VTE prophylaxis.

Inclusion Criteria:

1. Able to freely give written informed consent to participate in the study and have signed the Informed Consent Form;
2. Males or females, age 18 and older at the time of study screening;
3. American Society of Anesthesiologists (ASA) Class I-III (Appendix III);
4. Due to undergo major colorectal surgery via laparotomy or laparoscopy

Exclusion Criteria:

1. Mentally incompetent or unable or unwilling to provide informed consent or comply with study procedures;
2. American Society of Anesthesiologists (ASA) Class IV or V;
3. Children <18
4. Pregnant patients
5. Current/Active DVT
6. Patients on therapeutic anticoagulation for DVT or PE at time of surgery
7. Patients on anticoagulation for other medical problem (Heart Valve/atrial fibrillation) at the time of surgery
8. Patients with IVC filter
9. History of allergy to heparin products
10. History of heparin induced thrombocytopenia (HIT)
11. Patients with recent or active hemorrhage (GI/intracranial, etc) felt by the attending surgeon to be a contraindication to heparin thromboprophylaxis
12. Patients with Epidural analgesia