Stool normally contains a small amount of mucus, but passing stools with visible amounts of mucus can be from a variety of causes. Mucus in the stool is a common symptom of irritable bowel syndrome (IBS) and ulcerative colitis (UC), and is seen to a lesser degree in Crohn's disease (CD). A bacterial infection, anal fissure, or a bowel obstruction may also cause the passage of mucus.
Mucus is a clear, white, or yellow substance with the consistency of jelly which is produced by the mucus membrane of the large intestine. Mucus is also produced by other organs in the body such as the lungs, where it helps to trap any foreign particles that are inhaled. In the intestine, mucus protects the inner lining and helps ease the passage of stool.
Ulcerative Colitis and Irritable Bowel Syndrome
In UC, the mucus membrane of the intestine becomes inflamed and develops ulcers. These ulcers bleed and produce pus and mucus, which may be visible as they are passed in the stool. In IBS, there may be increased mucus production by the lining of the intestine, which is then passed. Mucus is more often associated with diarrhea-predominant IBS. Mucus is less frequent with CD, but may be associated with the development of an anal fissure.
Bacterial Infections
Bacterial infections, such as those from Campylobacter, Salmonella, Shigella, and Yersinia may also cause mucus in the stool. A bacterial infection may also cause diarrhea, fever, and abdominal cramps. Some bacterial infections may resolve on their own without treatment, but some cases may be serious and require treatment with antibiotics.
Bowel Obstruction
A bowel obstruction is associated with constipation, severe cramps, abdominal distention, and vomiting as well as the passage of mucus. A bowel obstruction can be from a variety of causes and is typically treated in the hospital, with surgery being necessary in some cases.
The passage of mucus in the stool in the setting of IBS or UC is not necessarily a cause for alarm, but should be mentioned to a physician. Mucus without an underlying cause such as a pre-existing condition should be reported to a physician immediately.
