Pilonidal Sinus

What is it?

A pilonidal sinus is a small skin pit in the mid line between the buttocks. It connects to buried hairs under the skin. The word pilonidal means “a nest of hairs”.


What causes it?

The exact cause is unknown but in most cases the buried hairs are responsible for irritation and inflammation of the area.  The area then becomes infected leading to an abscess.

People who have very deep pits at the top of the buttocks are more likely to develop them.
The condition is often recurrent and 2/3rds of cases occur in young men who have a lot of body hair. However it can also occur in young women.

What are the symptoms?

Pain and swelling between the buttocks. Patients can also present with recurrent discharge and minimal pain.



If the infection is acute and very painful then it may be necessary to lance the abscess.
Conservative treatment is to open the pit and remove the buried hairs. This is effective in 80% of cases. If this is not successful then an operation with a skin flap can be performed.