F11 and hyperinsulinemic hypoglycemia, familial, 4: In summary, despite the poor relationship between coagulation factor levels and bleeding symptoms, the factor level seems to be the most important parameter influencing the perioperative factor replacement decision-making in patients with FVII or FX deficiency, whereas it is less important for patients with FXI deficiency for whom the surgical site and the clinical phenotype seem to be the best criteria.