Introduction
Severe haemophilia A is a X-linked bleeding disorder due to factor VIII deficiency[1]. It decreases thrombin generation (TG) potential[2]. Inhibitor[3],[4] complicated replacement treatment (factor VIII concentrates[5]). Emicizumab (bispecific humanized monoclonal antibody) is an effective treatment for severe haemophilia A with inhibitor[6],[7]. It bridges activated factor IX and X to restore missing activated factor VIII[8]. Patients under emicizumab (Hemlibra® , Roche, Bazel, Switzerland) bleed less than patients under bypassing agent (BPA)[9],[10]. They still have acute bleeding needed BPA, mainly FVIIa (Novoseven® ,rVIIa, Novonordisk, Bagsvaerd, Denmark)[11]. Surgeries require BPA for bleeding risk but BPA doses for patients under emicizumab are not defined. Thrombin generation assay (TGA)[12] has been used to monitor surgery with Novoseven® [13] and could assess haemostasis when emicizumab and BPA are combined[14].