Overview, Causes, & Risk Factors
An anorectal abscess is a pocket of pus that forms in the anus and/or the area just above it, called the rectum.
What is going on in the body?
Most anorectal abscesses begin as bacterial infections of the glands in the anus that produce mucus. Infection can cause inflammation. Inflammation creates a wall around the bacteria and forms an abscess. This protective wall makes it hard for the immune system to fight the bacteria.
What are the causes and risks of the condition?
Most anorectal abscesses are caused by bacterial infection in the lining of the anus or rectum. Factors that increase a person's risk for an abscess include:
inflammatory bowel diseases, including Crohn disease and ulcerative colitis
immunodeficiency disorders, such as HIV
Symptoms & Signs
What are the signs and symptoms of the condition?
Pain in the rectal area is the most common symptom of an anorectal abscess. The pain may be dull, aching, or throbbing. It is worse when the person sits down and right before a bowel movement. After the individual has a bowel movement, the pain usually lessens. Other signs and symptoms of anorectal abscess include:
drainage from the rectum
fever and chills
loss of appetite
a mass in the rectum
Diagnosis & Tests
How is the condition diagnosed?
Diagnosis of anorectal abscess begins with a medical history and physical exam. Diagnostic studies of the anus or rectum can determine the size of the abscess. This may include special X-ray tests, such as an MRI or ultrasound.
An anoscopy may be done to give the healthcare provider a direct look at the inside of the bowel. A special thin tube with a camera and light on the end of it is inserted into the anus and advanced into the bowel.
Prevention & Expectations
What can be done to prevent the condition?
Anorectal abscesses cannot always be prevented. Early treatment of erosions of the bowel lining can help prevent an anorectal abscess. Stool softeners can be used to improve chronic constipation. Effective treatment of underlying disorders, such as diabetes, can lower the risk of abscess formation.
What are the long-term effects of the condition?
An anorectal abscess that is untreated or not fully healed can get worse. It can develop into a fistula or a life-threatening infection. A fistula is an abnormal opening or tract that connects two organs that are not supposed to be connected.
What are the risks to others?
An anorectal abscess is not contagious and poses no risk to others.
Treatment & Monitoring
What are the treatments for the condition?
Treatment of an anorectal abscess usually involves surgery to drain the pus pocket. Antibiotics and pain medicines may be prescribed.
What are the side effects of the treatments?
Surgery can cause bleeding, a worse infection, or allergic reaction to the anesthesia. Antibiotics and pain medicines can cause allergic reactions and stomach upset.
What happens after treatment for the condition?
After successful treatment and recovery, a person can generally return to normal activities.
How is the condition monitored?
Someone with inflammatory bowel disease often needs lifelong monitoring by a healthcare provider. Any new or worsening symptoms should be reported to the healthcare provider.