To date, low molecular weight heparins (LMWH) are most commonly used for VTE prophylaxis in the aforementioned population. Due to the pharmacologic properties of LMWH and the characteristics of surgically treated obese patients, the optimal dose that is to be utilized for VTE prophylaxis in this population remains unclear. Assessment of anti-FXa levels in the patients' plasma can be used in order to monitor LMWH activity. Levels of 0.2-0.5 U/ml have been proposed by some authors for VTE prophylaxis.