Factor II deficiency is a blood clotting (coagulation) problem that occurs when there is a lack of a substance (prothrombin) that is needed for blood to clot.

When you bleed, the body launches a series of reactions that help the blood clot. The process involves special proteins called coagulation factors. Factor II is one of many coagulation factors. The final product of these chain reactions is the blood clot.

When certain coagulation factors are too low or missing, your blood may not clot normally. Bleeding may range from mild to severe.

Factor II deficiency that runs in families (inherited) is very rare. It results in poor blood clotting. Both parents must be carriers to pass it to their children. A family history of a bleeding disorder is a potential risk factor.

Most commonly, factor II deficiency is caused by:

• Lack of vitamin K (or deficiency) from long-term use of antibiotics, bile duct obstruction, or poor absorption of nutrients from the intestines (intestinal malabsorption)
• Severe liver disease
• Use of drugs that prevent clotting (anticoagulants)

Some babies are born with vitamin K deficiency.