Assessment of bleeding risk in patient with FXI deficiency. This figure represents our suggested stepwise approach for assessing bleeding risk for patients with FXI deficiency before planned surgical interventions. Emphasized words demonstrate the “danger signals” increasing the risk of bleeding. Patient history and surgical site should always be considered. Sites with increased fibrinolytic activity include the genitourinary tract, and the nasal and oral cavities. The dark arrows represent the mandatory laboratory tests that should include bleeding evaluation (CBC, fibrinogen, PT, aPTT, VWD panel, FXI levels, and presence of FXI inhibitor, if relevant), whereas the dotted arrows provide additional information that may be helpful (eg, FXI mutations∗, global assays∗∗ including assessment of clot formation/fibrinolysis). ∗In general, because FXI genotype and levels do not necessarily predict bleeding risk, it is not cost-effective to routinely perform FXI molecular genetic studies. However, among patients with the severest FXI deficiency (FXI < 1%), we suggest confirming the presence of null mutations, because these patients may be at risk of inhibitor development. ∗∗Global assays may be considered for additional hemostatic assessment only in patients with severe FXI deficiency (FXI 0%-20%). CBC, complete blood count; PT, prothrombin time; ROTEM, rotational thromboelastometry; TEG, thromboelastography; VWD panel, von Willebrand antigen and activity (cofactor ristocetin) as well as platelet aggregation.