Factor I deficiency is a blood-clotting disorder that results in excessive or prolonged bleeding after an injury or surgery. Factor I is one of 13 proteins involved in proper formation of blood clots. Blood clots are needed to heal wounds, form scabs, and stop bleeding. When factor I levels are low or absent, the blood does not clot correctly, leading to excessive bleeding. Factor I deficiency runs in families and affect both males and females equally. The main symptom of factor I deficiency is excessive and abnormal bleeding. This may occur after childbirth, surgery, trauma, and with menstruation (periods). Bleeding can also occur in the muscles, joints, the mouth, the gut, or, infrequently, the brain. Easy bruising and nosebleeds are also common. Factor I deficiency can be diagnosed by a physician using blood tests. Treatment for factor I deficiency is largely based on controlling bleeding and treating any underlying conditions that contribute to excessive bleeding. When necessary, excessive bleeding can be stopped with infusions of clotting factors into the blood.