Recurrent Thrombi in an Obese Patient With History of Bariatric Surgery Despite Anti-Xa Therapy

Obesity and gastric bypass surgery can complicate anticoagulation therapy. In general, patients post-bariatric surgery are considered to be at a moderate risk for deep venous thromboembolism or pulmonary embolism. American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists guidelines recommend chemical prophylaxis with unfractionated heparin or low molecular weight heparin after surgery until the patient is fully mobile, and for those who require chronic anticoagulation, the International Society of Thrombosis and Haemostasis recommend warfarin if body mass index (BMI) is above 40 kg/m² or weight is more than 120 kg. Clinical decision making regarding anticoagulation in the following patient case is complicated by multiple factors, most notably the combination of obesity and history of gastric bypass surgery. This patient failed multiple anticoagulation regimens, with apixaban and rivaroxaban therapies each ending in venous thromboemboli and warfarin leading to subtherapeutic International Normalized Ratio (INR)s despite dose adjustment. However, she is currently therapeutic on the combination of enoxaparin and warfarin as shown by INR and anti-Xa level monitoring. In this case and similar instances, there could be a need for anticoagulant dose adjustments, different INR goals, or a combination of different anticoagulants. Providers should take an individualized approach to patients who have had bariatric surgery with elevated BMI as a key factor in anticoagulant selection.