Overview

A pilonidal sinus is a swollen (inflamed) track that leads into a small hole under the skin between the cheeks of your bottom. The groove or crease where your buttocks divide is called the cleft.

If you have a pilonidial sinus, this can cause pain and swelling. It might get infected and turn into an abscess, which can be very painful. An abscess is a swollen lump, which is filled with pus and made by infected tissue.

Causes of a pilonidal sinus

A pilonidal sinus often forms because hairs curl over and grow into your skin. This can cause an infection. You can also get a pilonidal sinus because of long-term swelling (inflammation) and infection of the skin.

The NHS website has more information about the causes of a pilonidal sinus and how to check if it is infected.

Treating a pilonidal sinus

A pilonidal abscess can burst by itself, or it can be treated with antibiotics. However, surgery is often the only way to treat the cause of the abscess and remove all the infected tissue. This is also called an excision.

Your doctor has recommended surgery to treat your pilonidal sinus.

There are different types of surgery, depending on the size of your pilonidal sinus and your symptoms.

Before surgery

Before you have surgery for a pilonidal sinus, your doctor or nurse checks your general health. They:

• ask you questions about your medical history (your present and past conditions and treatments)
• talk to you about the surgery in more detail

Please ask your doctor or nurse any questions that you have.