Stool normally contains a small amount of mucus, but passing stools with visible amounts of mucus could be from one of several different diseases or conditions. Mucus in the stool is a common symptom of irritable bowel syndrome (IBS) and ulcerative colitis (a form of inflammatory bowel disease), and is seen to a lesser degree in Crohn's disease. A bacterial infection, anal fissure, or a bowel obstruction may also cause the passage of mucus along with stool.
Mucus is a clear, white, or yellow substance with the consistency of jelly that 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 intestines, mucus protects the inner lining and helps ease along the passage of stool. Passing mucus in the stool is not harmful in and of itself, but it could be a symptom of a disease or condition that may require treatment.
In ulcerative colitis, the mucus membrane of the large intestine (colon) becomes inflamed and develops ulcers. These ulcers bleed and may also produce pus and mucus. The mucus may be voluminous enough that it can be seen as it is passed along with the stool.diarrhea-predominant IBS than with constipation-predominant IBS or alternating type IBS (IBS-A).
Bacterial infections, such as those from Campylobacter, Salmonella, Shigella, and Yersinia, may cause mucus to be passed in the stool. A bacterial infection may also cause symptoms of 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.
A bowel obstruction is associated with symptoms of constipation, severe cramps, abdominal distention, and vomiting, as well as the passage of mucus. A bowel obstruction could be caused by one of many conditions such as impacted stool, adhesions (scar tissue), a hernia, gallstones, a tumor, or swallowing a non-food item. Obstructions are typically treated in the hospital, with surgery to remove the blockage being necessary in some cases.
The passage of mucus in the stool in the setting of IBS or ulcerative colitis is not necessarily a cause for alarm, because it can be a sign of those conditions, but it should still be mentioned to a physician at the next office visit. Mucus without an underlying cause, such as one of the pre-existing conditions mentioned above, is a change in bowel habits and should be reported to a physician immediately.