Institutional Review of Therapeutic Enoxaparin Hemorrhagic Complications in Morbid Obesity

Ellen A Carraro, MD, Dean J Mikami, MD, Bradley J Needleman, MD, Sabrena F Noria, MD, PhD. The Ohio State Wexner Medical Center

Introduction: Enoxaparin, a low molecular weight heparin, is often used prophylactically to reduce the risk of thromboembolic events, and therapeutically to bridge to full oral anticoagulation postoperatively.  In individuals with obesity (BMI > 30kg/m2), there is concern regarding the optimal dosing as drug distribution and pharmacokinetics may be altered.  While laboratory evaluation with anti-Xa levels has been proposed, risk of thrombosis and hemorrhage have not been shown to correlate well with anti-Xa levels. Overall risk of major hemorrhagic complications on low molecular weight heparin is 1.1%, however we noted several bleeding complications in our patient population and decided to evaluate our experience and identify risk factors that may be contribute to hemorrhagic complications.

Methods: A retrospective chart review was performed on postoperative patients discharged, from a single surgical service, on therapeutic enoxaparin as a bridge to full anticoagulation from “year start” to “year finish”. Demographic informations, surgical intervention and surgical complications were reviewed to assess risks related to anticoagulation.

Results: A total of 41 patients met the inclusion criteria. The mean age was 49.8 years with 68% females and a mean BMI of 47.0 kg/m2. Surgical interventions included, sleeve gastrectomy (36.6%), abdominal wall hernia repair (26.8%), Roux en Y gastric bypass (22%), exploratory laparotomy (9.7%) and others (2.4%).  The indication for anticoagulation included a history of deep vein thrombosis/pulmonary embolism (75.6%), atrial fibrillation (14.6%), portal vein thrombosis (4.9%), and other (4.9%). Fifteen (36.6%) patients were readmitted for complications directly related to their surgical intervention.  Of these, 3 (7.6%) were admitted secondary to hemorrhagic complications and specific interventions included, (1) medical management with blood transfusion and reversal of supratherapeutic anticoagulation, (2) transfusion and stenting of subsequent, possible resultant, gastric sleeve leak, and (3) transfusion and empiric embolization.

Conclusions: Post-operative bridging of morbidly obese patients with therapeutic enoxaparin should be approached with caution as the incidence of hemorrhagic complications may be greater than expected.  However, further studies are needed to identify those at increased risk of complications including more consistent evaluation of anti-Xa levels, both at initial administration and at readmission, in order to adjust dosing or pursue alternative options for anticoagulation. 

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