Preoperative coagulation indices in patients with morbid obesity

Preventive measures against venous thromboembolism are used frequently in surgical patients with morbid obesity because the risk has been claimed to be higher than usual. We addressed this risk in 81 morbidly obese patients by measuring preoperative plasma proteins associated with coagulation and by correlating variations in these indices to excess weight, liver histology, patient sex, tobacco use and serum triglycerides. Plasma levels of antithrombin III and plasminogen were normal in these patients. Plasma fibrinogen concentrations were elevated in 34 percent of patients; the values did not relate to excess weight and they correlated negatively (P less than 0.04) with increasing serum triglycerides and grades of liver fat content. Premenopausal women had higher plasminogen and fibrinogen levels than menopausal women or men, although their mean levels were normal. Smokers had lower plasminogen levels than nonsmokers (P less than 0.01). However, none of the measured levels of preoperative coagulation proteins identified increased risk for venous thrombosis in cohorts of this population, and the coagulation indices were not different from those reported in normal weight patients.