Pilonidal sinus
Overview
A pilonidal sinus is a small hole or tunnel at the top of your bottom, between your buttocks. Treatment is usually only needed if it becomes infected.
Symptoms
Most people with a pilonidal sinus do not notice it unless it becomes infected and causes symptoms. An infection will cause pain and swelling at the top of the cleft in your buttocks, and a pus-filledskin abscesscan develop. Sometimes a pus-filled abscess can develop suddenly, causing pain and swelling, and making it difficult to sit down. If you keep getting infections you may have ongoing problems, like discomfort or pain, and regularly seeping pus or blood.
Causes
It's not clear what causes a pilonidal sinus. A skin problem, pressure or friction may cause hair between the buttocks to be pushed inwards. This may either be hair growing around the buttock area, or loose hair shed from the buttocks or elsewhere that gathers around the buttock cleft and enters the pilonidal sinus. Pilonidal sinuses are more common in men because they tend to be hairier. Sitting for long periods can also increase your chances of getting a pilonidal sinus.
Treatment
Treatment for an infected pilonidal sinus will depend on: your symptomsthe size of the pilonidal sinuswhether it's your first infected pilonidal sinus or it keeps coming back If you have a painful, swollen abscess, it usually needs to be cut and the pus drained. You may also needantibiotics. There are a number of treatment options for a pilonidal sinus that keeps coming back and that's painful, bleeding or leaking discharge. Your doctor will discuss these with you. In most cases you'll be offered painkillers, such asparacetamolandnon-steroidal anti-inflammatory drugs (NSAIDs), to help reduce pain and swelling. Plastic surgeryis sometimes used if the area being treated is particularly large. The sinus is removed and the surrounding skin reconstructed. Less invasive procedures to close the sinus, like injection with fibrin glue, may be available in some places.