Pilonidal sinus

A pilonidal sinus is a small hole or tunnel in the skin at the top of the buttocks, where they divide (the cleft). Most people with a pilonidal sinus don’t notice it until it becomes infected and causes symptoms.

What is a pilonidal sinus?

A pilonidal sinus is a chronic infection beneath the skin, usually of the natal cleft (between the buttocks). It typically contains hair, usually the same type that is found on the head.

What causes a pilonidal sinus?

The condition is more common in men than women, often between puberty and age 40, and in obese people or those with thick, coarse body hair. The chronic infection is due to the hairs trapped beneath the skin. Whether the hairs actually grow there from trapped scalp-like skin or whether they ‘drill’ in from the outside is the subject of debate. Probably both occur.

What are the symptoms?

Sometimes a pilonidal sinus causes no symptoms at all. More often there is a small tender dimple or a large painful abscess. The area may drain fluid that may be clear, cloudy of bloody. When infected, the area may become red and tender with pus draining from it.

Often the first indication of a pilonidal sinus is an acute episode of infection with an abscess. After the anscess resolves (either spontaneously or with antibiotics), a pilonidal sinus may develop. A sinus is a cavity beneath the skin surface that connects with the surface of the skin with one or more openings or tracts.

How is a pilonidal sinus treated?

Treatment depends largely on the pattern of the disease. Often careful removal of hair and inflammatory tissue from the sinus can be performed in the rooms, and healing can be achieved over a number of sessions. 

An acute abscess may require an incision (cut) to release and drain the collection of pus. This can be performed in the rooms using local anaesthetic.

If the disease is complex, recurrent or chronic, it requires surgical treatment performed in a operating theatre. This will involve excision of the sinus tracts, which may be simple or extensive. The wound may be closed with skin flaps, or sutured closed, or left open. Larger operations require longer healing times. 

Your surgeon will discuss the options with you and help you select the appropriate operation. 

Whatever treatment is used, it is most important that the area be kept hair free by shaving, depilating cream or laser hair removal.