Vincent Chavanon, Medical Student, Gabriel E Herrera, MD, Giselle Hamad, MD. University of Pittsburgh Medical Center, University of Pittsburgh
Introduction: Obesity is an independent risk factor for the development of venous thromboembolism (VTE), which can add significant morbidity and mortality to bariatric surgery procedures. Obesity has been shown to be associated with hypercoagulable disorders. There is no consensus regarding the optimal method of thromboprophylaxis or the appropriate method for VTE risk stratification in bariatric surgery candidates. A better understanding of the hypercoagulability disorders associated with obesity may prompt the implementation of preventive strategies to decrease the postoperative incidence of VTE. The purpose of this study was to determine the prevalence of thrombophilias in this high-risk population.
Methods: Between August 2008 and March 2011, all bariatric patients undergoing preoperative evaluation for surgery underwent risk assessment for VTE. Risk factors for VTE were assessed, including personal or family history of VTE, body mass index (BMI) ≥ 60 kg/m2, pulmonary hypertension, obstructive sleep apnea, tobacco use, oral contraceptive use, hormone replacement therapy, and immobility. Serologic evaluation included platelet count, coagulation profile, and screening for thrombophilias. All patients were screened for the presence of both inherited thrombophilias (Protein C or S deficiency, Factor V Leiden, MTHFR mutation, prothrombin gene mutation and antithrombin III deficiency) and acquired thrombophilias (lupus anticoagulant and hyperhomocysteinemia). The prevalence of thrombophilias was determined. Patients were given heparin 5000 IU s.c. preoperatively and enoxaparin 40 mg s.c. every 12 hours postoperatively. Patients with hypercoagulable disorders, prior VTE, or BMI ≥ 60 kg/m2 were given extended prophylaxis with enoxaparin 40 mg b.i.d. for two to four weeks. Preoperative retrievable inferior vena caval (IVC) filters were placed in patients with prior VTE or BMI ≥ 60 kg/m2. The incidence of postoperative VTE was determined in the initial 30-day postoperative period.
Results: During the study period, 213 patients underwent preoperative bariatric evaluation and risk assessment for VTE. Overall, 98 patients (46%) were diagnosed with at least one thrombophilia, and 22 patients (10.3%) had 2 or more thrombophilias. The prevalence of inherited thrombophilias was: protein C deficiency (1%), protein S deficiency (1.5%), Factor V Leiden (3%), MTHFR C677T homozygous (9.9%), MTHFR A1298C homozygous (7.8%), prothrombin gene mutation (3.6%) and antithrombin III deficiency (1%). The prevalence of acquired thrombophilias was: lupus anticoagulant (8.2%), and hyperhomocysteinemia (15.6%). Preoperative retrievable IVC filters were placed in 21 (9.9%) patients and extended prophylaxis was used in 76 (35.8%). One patient (0.46%) had a postoperative hemorrhage on the night of surgery and required reoperation. There was one pulmonary embolism (0.46%) on postoperative day 1 in a patient with hyperhomocysteinemia and compound heterozygous MTHFR. Another patient with one copy of the MTHFR gene had a deep vein thrombosis (0.46%) on day 21, 2 days after discontinuing the extended prophylaxis. There were no mortalities.
Conclusion: A substantial proportion of bariatric surgery patients present with inherited and acquired thrombophilias. Among the patients who received extended prophylaxis, the incidence of VTE was low. The preoperative screening for thrombophilias is a useful tool in guiding thromboprophylaxis in bariatric surgical patients.
Session Number: SS04 – Quality Outcomes
Program Number: S018