Prevalence of Deep Vein Thrombosis in Low Risk Patients After Elective Foot and Ankle Surgery

Category: Surgical complications Introduction/Purpose: For patients undergoing elective foot or ankle surgery deep vein thrombosis is a recognised risk with morbidity.The literature is often based on a retrospective review of the clinical notes which can be misleading. Surveillance has not been done in the past .Our concern was that the true incidence of DVT may have been underreported and silent DVTs are possible . The study prospectively determines the prevalence of DVT in low risk patients who are non weight bearing for 6 weeks post operatively by having patients undergo clinical detection as well as high resolution ultrasound to determine the presence and extent of deep vein thrombosis (DVT) in the patients operated leg at 2 weeks and 6 weeks after surgery. Methods: 197 patients undergoing elective (i.e. not trauma or achilles ruptures) foot or ankle surgery requiring a period of 6 weeks non weight bearing post operatively were selected for the study over a 2 year period. 83 patients were excluded as being high risk for DVT based on recognised criteria. The remaining 114 patients were included in the study as they were low risk for DVT. All 114 patients were assessed clinically at 2 weeks and 6 weeks post op for the possibility of DVT and this was recorded.The patients were then sent for high resolution U/S scans on the affected leg at 2 and 6 weeks after the surgery . A middle frequency (4-9 MHz) transducer was used for the study, and a lower frequency transducer for obese or swollen legs. The scans were performed at the Vascular Lab at our Institution which performs over 10000 scans annually. Results: 114 patients were in the study. 71 Females and 43 males with average age 52 years . The incidence of DVT was 24.56% (28/114). Of the 28 positive scans, 22 (79%) had no clinical symptoms or signs of DVT. 20/28 (71%) DVTs were diagnosed at the 2 week scan and 15 of these had no symptoms or signs of DVT. 8/28 (29%) patients had clear scans at 2 weeks and positive scans at 6 weeks.In this late onset group 7/8 had no symptoms or signs of a DVT. Only 5% (6/114) patients had symptoms or signs of DVT. The incidence of DVT in the first 2 weeks after surgery was 17.5%. Of the remaining 94 patients, 8.5% developed a DVT after 2 weeks. Conclusion: In low risk patients who are non weight bearing for 6 weeks after elective foot or ankle surgery the prevalence of DVT (25%) is significantly higher than the literature suggests and the majority of patients 79% (22/28) had no symptoms or signs of DVT to assist in the diagnosis. The majority of DVT’s occurred in the first 2 weeks after surgery however 29% of the total number of DVTs occurred between week 3 and week 6 non weight bearing