Major abdominal surgery for cancer is major risk factor for thromboembolism. Patients who undergo major abdominal surgery are prone to develop venous thromboembolism, both in the early postoperative period and after hospital discharger. There are strong recommendations in the international guidelines in favor to pharmacological thromboprophylaxis. Thus there is no consensus dor the duration of the prophylaxis. There are authors that suggest extended prophylaxis up to 4 week after surgery. On the other hand, there are prospective randomized trials that inpatient (short-term up to 7-10 days) prophylaxis is adequate.

This is a retrospective cohort study with 89 patients who underwent major abdominal surgery for colorectal and gastric cancer. All patients received short term prophylaxis (during hospital stay only) rather than extended prophylaxis (4 weeks). All participants received duplex ultrasound in the study period for the diagnosis of deep vein thrombosis.

Inclusion Criteria:

• Older than 18
• Major abdominal surgery gor colorectal or gastric cancer
• Caprini Risk score less than 9
• No history of anticoagulant treatment
• Thromboprophylaxis during hospital stay only

Exclusion Criteria:

• Younger than 18
• Caprini Risk score 9 and above
• History of anticogulants
• Not reachable by phone etc