Eligibility Criteria:
Inclusion Criteria:
* Undergoing abdominal surgery (any surgery between the diaphragm and pelvic floor) lasting longer than 45 minutes (duration from anesthesia induction to surgical closure)
* Over 40 years of age
* Subject who had signed the informed consent.
Exclusion Criteria:
* Active, clinically significant bleeding
* Documented congenital or acquired bleeding tendency/disorders
* Active ulcerative gastrointestinal disease unless the reason for the present surgery.
* Recent intracranial hemorrhage or recent (less than 3 months prior to randomisation) brain, spinal, or ophthalmologic surgery.
* Indwelling intrathecal or epidural catheters for more than 6 hours after surgical closure.
* Subjects who had a traumatic puncture or unusual difficulty in applying the catheter
* Known cerebral metastasis,
* Subjects in whom hemostasis had not been established 6 hours after surgical closure,
* Current thrombocytopenia,
* Bacterial endocarditis
* Creatinine level above 2.0 mg/dL (180 μmol/L) in a well-hydrated subject,
* Documented hypersensitivity to contrast media,
* Use of any contraindicated drug that could not be combined with the injection of contrast medium,
* Patent with evidence of leg ischemia caused by peripheral vascular disease, unable to undergo IPC and unable to wear Elastic Stockings.
Exclusion criteria related to trial methodology:
* Mental disorders that could interfere with study participation and/or failure to give written informed consent to take part in the study,
* Subject's life expectancy \< 6 months,
* Clinical sign of DVT and/or history of recent DVT,
* Participation in any other therapeutic drug study or a device study evaluating DVT prophylaxis within 90 days preceding inclusion,
* Previous participation in a study of fondaparinux sodium,
* Known hypersensitivity to fondaparinux and its excipients,
* Current addictive disorders that could interfere with study participation,
* Administration of heparin, heparinoids, LMWH, oral anticoagulants, dextrans, hirudin, fibrinolytic agents or drugs blocking glycoprotein platelet receptors (GPIIb-IIIa) during the screening period, i.e., from admission to surgery,
* Subjects for whom anticoagulant therapy was contraindicated or who had, due to concomitant disease, an indication for oral anticoagulant or heparins (including LMWH) and who could not discontinue those treatments,
* Women of child-bearing potential: women not using an appropriate contraceptive method during the whole duration of study participation ,
* Subject with body weight \<50 kg,
* Subjects, who in the opinion of the investigator, required a pharmacological prophylaxis in addition to intermittent pneumatic compression,
* Known pregnancy and / or women who intended to breastfeed,
* Subjects undergoing vascular surgery such as aorto-femoral bypass graft