For patients in the study group: high-moderate risk of deep vein thrombosis (for the administration of LMWH for 30 days after surgery) under general anesthesia> 30 minutes, laparoscopy + at least one risk factor (age> 40 years, obesity, varicose veins, previous episode of deep vein thrombosis and / or pulmonary thromboembolism, thrombophilia, malignancy, prolonged immobility, congestive heart failure)