What is a pilonidal abscess?
A person with pilonidal abscess has an infected pilonidal cyst, which is collection of fluid under the skin between the buttocks. A pilonidal abscess is caused by bacteria that are normally on the surface of the skin. The bacteria enter the pilonidal cyst and start to grow. The infection causes pus to collect inside the cyst, resulting in an abscess.

What are the symptoms of a pilonidal abscess?
Symptoms of a pilonidal abscess include a tender, painful lump under the skin between the buttocks. Additional symptom of a pilonidal abscess include skin redness and swelling. Pus may drain from the abscess.

How does the doctor treat a pilonidal abscess?
Treatment for a pilonidal abscess may include warm baths, antibiotics, narcotic pain medications, and nonsteroidal anti-inflammatory medications. A pilonidal cyst may also require incision and drainage, which is a procedure that allows pus to drain from the abscess.