Recombinant Human Antithrombin (rhAT) in Patients With Hereditary Antithrombin Deficiency Undergoing Surgery or Delivery

Up to 24 hours prior to the scheduled elective surgical procedure, caesarean section, or delivery induction, each patient will receive an initial intravenous loading dose followed by a continuous intravenous infusion of recombinant human antithrombin (rhAT) that will target and maintain an AT activity that is \> 80% and \< 120% of normal. The dosing objective for all study patients is maintenance of the AT activity at \> 80% and \< 120% of normal during the high-risk period for thromboembolic events. Dosing and dose adjustments will be based on the results of AT activity determinations performed prior to and during treatment.