The Anus: Anatomy and Role in Bowel Health

The anus is the opening at the end of the digestive system where stool leaves the body. It is connected to the rectum and plays an important role in bowel control, passing stool and noticing symptoms such as bleeding, pain or changes around the anal area.

This article is for general information only. If you have bleeding, pain, a lump, itching, discharge or changes around the anus, speak with a doctor or qualified healthcare professional.

What Is the Anus?

The anus is the final opening of the large bowel. The rectum stores stool before it leaves the body, and the anus is the passage where stool exits. The anal canal and anus are part of the lower digestive system. NCI describes the anal canal as ending at the anus, the opening of the large intestine to the outside of the body. :contentReference[oaicite:0]{index=0}

How the Anus Helps With Bowel Control

The anus contains muscles that help control when stool and gas leave the body. These muscles are called sphincters. They work with the rectum, nerves and pelvic floor muscles to help with continence and bowel movements.

Problems with these muscles or nearby nerves can sometimes affect bowel control, especially after certain surgeries or pelvic treatments.

Symptoms Around the Anus

Symptoms around the anus can have many causes. Haemorrhoids, fissures, infections, skin irritation, inflammatory bowel disease and cancer can sometimes cause symptoms in this area.

Symptoms that should be checked include bleeding, persistent pain, a lump, unusual discharge, ongoing itching, change in bowel control or symptoms that do not improve.

Anal Symptoms and Bowel Cancer

Bowel cancer usually starts in the colon or rectum, but symptoms may sometimes be noticed when passing stool, such as blood in the stool or bleeding from the rectum. These symptoms do not always mean cancer, but they should be discussed with a doctor if they are persistent or unexplained.

For related information, read our What Are the Symptoms of Bowel Cancer? and General Tests and Physical Examination for Bowel Cancer articles.

After Bowel Cancer Treatment

Some bowel cancer treatments, especially surgery or radiation therapy near the rectum and pelvis, may affect bowel control, comfort or sexual function. If you notice changes after treatment, speak with your healthcare team.

You may also find our Side Effects of Bowel Surgery and Managing Bowel and Dietary Changes guides helpful.

Final Thoughts

The anus is an important part of bowel health and bowel control. Because symptoms in this area can have many causes, persistent bleeding, pain or unusual changes should be checked by a healthcare professional.