Is LMWH Sufficient for Anticoagulant Prophylaxis in Bariatric Surgery? Prospective Study

The objective of this study was to evaluate the coagulation profile by thromboelastography in morbidly obese patients who undergo bariatric surgery. Morbid obesity entails increased risk for thromboembolic events. There is no clear protocol for thromboembolic prophylaxis, regarding timing and length of treatment, in bariatric surgery. Thromboelastography provides data on a coagulation process from creation of the clot until the fibrinolysis.

Ninety-three morbidly obese patients were prospectively recruited within a 2-year period. Coagulation profile was measured by thromboelastography before surgery, in the immediate postoperative period, within 3 h from surgery, and in the late postoperative period, within 10-14 days after surgery. Venous thromboembolic prophylaxis was achieved by giving low molecular weight heparin (LMWH), once a day.

Of the eligible patients, 67 underwent sleeve gastrectomy while 23 underwent Roux-en-Y gastric bypass. Normal values of coagulation factor function, clotting time, and fibrin function, as measured by R, K, and α (angle), were demonstrated in addition to higher maximal amplitude (MA) values, reflecting increased function of platelets. The average MA value before the surgery was above normal and continued rising consistently in the immediate postoperative as well as in the early postoperative period.

Morbidly obese patients have a strong tendency toward thrombosis, as demonstrated by pathologically elevated MA values. Altered coagulation profiles were demonstrated 2 weeks postoperatively; thus, prophylaxis that continued at least for 2 weeks after bariatric surgery should be considered. Since LMW heparin is not sufficient alone as thromboembolic prophylaxis, we recommend adding antiplatelet therapy. Further evaluation of appropriate thromboprophylaxis is warranted.