Factor V deficiency is an inherited condition that affects the ability of the blood to clot.

Normal blood coagulation is a complex process involving as many as 20 different proteins in blood plasma, which are known as blood coagulation factors. A series of complex chemical reactions using these factors takes place very rapidly to form a protein called fibrin, which stops bleeding.

Factor V deficiency is caused by a lack of the plasma protein Factor V. When certain coagulation factors are low or missing, the chain reaction does not take place normally. Factor V is rare, and can be caused by inheriting a defective Factor V gene or by acquiring an antibody that interferes with normal Factor V function.

You can acquire an inhibitor of Factor V:

• After giving birth
• After being treated with a certain type of fibrin glue
• After surgery
• With autoimmune diseases and certain cancers

Sometimes the cause is unknown.

The disease is similar to hemophilia, except bleeding into joints is less common. In the inherited form of Factor V deficiency, a family history of a bleeding disorder is a risk factor.

Excessive bleeding with menstrual periods and after delivery often occurs. Men and women are affected equally. About 1 person per 1 million has the disorder.

• Bleeding into the skin
• Bleeding of the gums
• Excessive bruising
• Excessive menstrual bleeding
• Nosebleeds
• Prolonged or excessive loss of blood with surgery or trauma
• Umbilical stump bleeding

• Factor V assay showing decreased activity
• Normal thrombin time
• Prolonged partial thromboplastin time
• Prolonged prothrombin time
• Slightly prolonged bleeding time (in some people)

You should receive fresh blood plasma or fresh frozen plasma infusions during a bleeding episode or after surgery. These treatments will correct the deficiency temporarily.

You can often help the stress of illness by joining a support group where members share common experiences and problems.

The outlook is good with diagnosis and proper treatment.

Severe bleeding (hemorrhage) could occur.

Go to the emergency room or call the local emergency number (such as 911) if you have an unexplained or prolonged loss of blood.

This is an inherited disorder; there is no known prevention.

Asselta R, Tenchini ML, Duga S. Inherited defects of coagulation Factor V: the hemorrhagic side. J Thromb Haemost. 2007;5:185-188.