Fibrinogen plays an important role in the coagulation cascade. Low levels of preoperative fibrinogen have been associated in adults with higher blood and transfusion requirements during surgery. Guidelines from the European Society of Anesthesiology and Intensive Care recommends fibrinogen substitution based on viscoelastic tests in adult cardiac surgery. Cardiopulmonary bypass results in a profound hemodilution and dilution of all coagulation factors. This is especially true in children where the priming volume of the cardiopulmonary bypass circuit is much higher compared to the patient's weight than in adults. Cardiopulmonary bypass generates high levels of tissue plasminogen activator resulting in a hyperfibrinolysis, further lowering fibrinogen levels.

The aim of this retrospective study is to explore a possible relationship between preoperative fibrinogen levels and perioperative blood loss, as well as transfusion requirements in children undergoing cardiac surgery.

Inclusion Criteria:

• all children with cardiac surgery under cardiopulmonary bypass between 2008 and 2018
• Age < 16 year

Exclusion Criteria:

• preoperative coagulopathy
• Jehovah's witnesses
• patients with fresh frozen plasma in the priming of the cardiopulmonary bypass circuit

All children under 16 year, with cardiac surgery under cardiopulmonary bypass between 2008 and 2018 at our institution