Overview

A pilonidal sinus is a swollen (inflamed) track that leads into a small hole underneath the skin between the cheeks of your bottom (the cleft, where your buttocks divide).

It can cause pain and swelling. If it becomes infected, it might turn into an abscess, which can be very painful. An abscess is a swollen lump filled with pus, made by infected tissue.

Causes of a pilonidal sinus

A pilonidal sinus often forms because hairs curl over and grow into your skin, which can cause an infection. It can also form because of long-term swelling (inflammation) and infection of the skin.

The NHS website has more information about causes and how to check if a pilonidal sinus 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 how large your pilonidal sinus is and your symptoms.

Before surgery

Before you have surgery, your doctor or nurse will go through some checks with you about your general health. They will ask you questions about your medical history, and talk to you about the surgery you are having in more detail. Please ask them any questions you have.