Epidemiology and treatment of congenital fibrinogen deficiency.

Congenital fibrinogen deficiency is a rare bleeding disorder, affecting either the quantity (afibrinogenemia, hypofibrinogenemia) or quality (dysfibrinogenemia) of circulating fibrinogen. There is a strong association between fibrinogen activity levels and clinical bleeding severity. Patients with afibrinogenemia experience frequent, often severe, spontaneous bleeds into the muscles and joints and are at significant risk of intracranial hemorrhage. Patients with hypofibrinogenemia are usually asymptomatic; however, they are vulnerable to bleeding after trauma. Dysfibrinogenemia is associated with both spontaneous bleeding and a relatively high risk of thrombosis. Fibrinogen replacement therapy is effective in treating bleeding episodes in congenital fibrinogen deficiency. Fibrinogen concentrates are the preferred treatment option and guidelines now exist for their on-demand use and to manage surgery. Prophylaxis may benefit patients with afibrinogenemia and others with a severe bleeding tendency. The dose and frequency of administration should be adjusted to maintain a fibrinogen activity level >0.5-1.0 g/L. Pregnant women with afibrinogenemia require prophylactic factor replacement as early as possible during pregnancy, continuing throughout pregnancy, and after the birth. Fibrinogen replacement should also be considered in pregnant women with other fibrinogen deficiencies. The risk of thrombosis presents an additional management challenge in these patients, often necessitating the concurrent use of anticoagulants and fibrinogen. Although basic guidelines have been developed, further studies are needed to help optimize treatment in different patient groups under different clinical circumstances and to improve our understanding of thrombotic events.