The objective of this study is to evaluate the safety and efficacy of aprotinin as compared to placebo, in reducing the need for blood transfusion in adult subjects undergoing elective spinal fusion surgery involving 3 to 7 vertebral levels with instrumentation

Inclusion Criteria:

• Subjects requiring elective spinal fusion surgery involving 3 to 7 vertebral levels with instrumentation. One vertebral level is defined as encompassing two vertebral bodies and one inter-vertebral disc space, so that a contiguous spinal fusion involving 3 vertebral levels would include 4 vertebral bodies and 3 inter-vertebral disc spaces.

Exclusion Criteria:

• Subjects with previous exposure to aprotinin in the last 6 months. If the subject has undergone cardiac surgery in the last 6 months, all attempts should be made to ascertain if aprotinin was administered during cardiac surgery. If no records are available, or if the subject received aprotinin, the subject should be excluded.- Subjects with a known or suspected allergy to aprotinin.
• Subjects with sepsis or a known bone infection.- Subjects with known bone malignancy.
• Subjects with a creatinine clearance less than 30mL/min as calculated by the Cockcroft-Gault formula.
• Subjects with a history of bleeding diathesis or known coagulation factor deficiency.
• Subjects with failure of a major organ system or any active significant medical illness that in the opinion of the Investigator is likely to affect the subject's ability to complete the study or precludes the subject's participation in the study
• Subjects who refuse to receive allogenic blood products for religious or other reasons.
• Subjects whose preoperative red blood cell volume is so low that a blood transfusion would be likely to be given perioperatively (preoperative hematocrit or hemoglobin values <24% or <8 g/dl, respectively).
• Subjects who have participated in an investigational drug study within the past 30 days
• Subjects with a history of deep vein thrombosis or pulmonary embolism.
• Subjects who are pregnant or breast feeding.
• Women of childbearing potential in whom the possibility of pregnancy cannot be excluded by a negative serum pregnancy test at screening.
• Women of childbearing potential who are not using a reliable method of contraception.
• Planned use of other antifibrinolytic agents.
• Subjects on chronic anticoagulant treatment with Vit K antagonists that cannot be temporarily discontinued for the surgical procedure (as per local practices).