A perianal abscess is (simply) a collection of pus, outside the anus. Infection of an anal fissure, sexually transmitted infections, and blocked perianal glands are all thought to be inciting factors. The abscess usually begins when bacteria enters through a tear in the lining of the rectum or anus. Most often, this occurs between the internal and external sphincters (intersphincteric abscess), where the perianal glands are located. As the abscess increases in size, most will follow the plane of least resistance and spread towards the surface, creating a perianal abscess.
Swelling around the anus and a constant, throbbing pain are the most common symptoms. Pain with bowel movements may be severe.
Other symptoms may include:
- Painful, hardened tissue
- Lump or nodule, swollen, red, tender at edge of anus
- Discharge of pus from the rectum
- Fatigue and general malaise
- Fever, night sweats, and chills
To treat an abdominal abscess, the pus must be drained, either by surgery or by a needle inserted through the skin. To guide the placement of the needle, a doctor uses CT or ultrasound scanning. Antibiotics are usually used in conjunction with drainage to prevent the infection from spreading and to help completely eliminate the infection.
Complications may include:
- Peritonitis stops the movement of bowel contents (peristalsis), which can block the bowel (paralytic ileus).
- Septic shock – Fluid from the blood accumulates in the abdominal cavity and the loss of fluid from the circulation may also cause shock.
- Intraperitoneal adhesions