A pilonidal sinus is a small hole or "tunnel" in the skin.It usually develops in the cleft of the buttocks where the buttocks separate.

More than one hole may develop, and often these are linked by tunnels under the skin.

Most people associate the word sinus with the nose, but sinuses can occur anywhere in the body. Sinus is simply a medical term for achannel or cavity.

A pilonidal sinus will not usually cause any noticeable symptoms unless it becomes infected. This can cause apus-filled Abscess to develop. Signs that you may have an infection include pain, rednessand swelling in the affected area.

Seeyour GP as soon as possible if you think you have a pilonidal sinus. Without treatment, any pain and infection may get worse.

Your GP should be able to diagnose a pilonidal sinus after looking at the affected area of skin. Further testing is not usually required.

It mayalso help toremove any hair near the sinus. These steps can reduce therisk of infection.

Showering at the end of the day to remove strayhairs from the cleft between your buttocks may also help.

If a pilonidal sinus becomes infected, it should be treated as soon as possible, as it's likely to get worse.

Treatment usually involves taking antibiotics andhaving the pus drained from the abscessduring a minor operation called incision and drainage.

Ifthe sinuskeeps becoming infected,it may have to besurgically removed. Several techniques can be used, including:

  • cutting out the sinus and leaving the wound openso it canheal, and packingitwith a dressing daily
  • closing the wound with a flap of skin and stitches
  • scraping out the sinuses and filling them with a special glue

Readmore about treating pilonidal sinus .

Who is affected?

Pilonidal sinuses are rare, affecting about 26 in 100,000 people each year.

They affect at least twice as many men as women. The average age for a pilonidal sinus is 21 in men and 19 in women.

They are less common in children and people over the age of 45.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 28 Nov 2016