Pilonidal sinus

A pilonidal sinus is an infected tract (commonly containing hair) under the skin between the buttocks.

A pilonidal sinus is a relatively common condition in young adults, rarely affecting children and people over the age of 40. It is much more common in men because they are hairier than women.

The precise cause of pilonidal sinuses is not clear. They may be caused by loose hairs pushing into the skin or by deep layers of skin being stretched and moved, leading to a hair follicle rupturing.

Alternatively, if a hair follicle becomes blocked, it can enlarge and burst - this may cause a hair to push into the skin, leading to an infection.

A number of factors increase your risk of developing a pilonidal sinus, including:

  • obesity
  • age (usually between the ages of 15 and 40)
  • sitting down (e.g. driving) for long periods
  • having above-average amount of body hair
  • having coarse body hair
  • a deep buttock cleft
  • a family history of pilonidal sinuses
  • a previous injury in the affected area

It's important to keep the area as clean and dry as possible. Removing hair from the area is also advisable, usually by shaving or using hair removal creams. This should reduce the risk of an infection.

A pilonidal sinus may not cause any noticeable symptoms unless it becomes infected. If the sinus becomes infected, an abscess will usually develop. This is a painful collection of pus that causes symptoms such as pain, tenderness, redness and possibly a draining of pus or blood.

Pilonidal sinuses don’t just occur near your buttocks; they can also develop on the belly button or between fingers.

The pain caused by a pilonidal sinus can be severe making it uncomfortable to sit or lie down. This may affect your sleep and your ability to carry out daily activities and work. The condition is likely to worsen without treatment so it’s important to see your GP quickly if you think you may have a pilonidal sinus.

Your GP will be able to diagnose the condition with a simple visual examination. If you suspect you have a pilonidal sinus, see your GP as soon as possible to discuss your treatment options. Pain caused by a pilonidal sinus can be severe and is likely to get worse without effective treatment.

Excision of pilonidal sinus

Treatment of a pilonidal sinus involves making a small surgical incision to open it and to allow the pus to drain away.

What next?

If you are suffering with a suspected condition, you should seek the advice of your doctor who will be able to refer you to Benenden Hospital for diagnosis and treatment.

There are four ways to access treatment at Benenden Hospital which include self-funding, using private medical insurance or your Benenden membership, or through the NHS e-Referral scheme.