Despite the known haemostatic action of emicizumab (Hemlibra) in haemophilia A patients, its role in the prevention and control of bleeding in high-demand haemostatic situations, such as major surgery, remains to be determined. Patients receiving regular emicizumab prophylaxis often require concomitant factor VIII (FVIII) therapy during major surgery to prevent uncontrolled bleeding and to promote postoperative healing. However, there are limited prospective surgical data relating to concomitant FVIII and emicizumab use. Simoctocog alfa (Nuwiq) is a B-domain deleted recombinant FVIII produced in a human cell line without chemical modification or protein fusion with proven efficacy as surgical prophylaxis in adult and paediatric patients. The Nuwiq for Perioperative management Of patients With haemophilia A on Emicizumab Regular prophylaxis (NuPOWER) study aims to examine perioperative efficacy and safety of simoctocog alfa in haemophilia A patients on emicizumab prophylaxis undergoing major surgery.