Mucus in stool
By Dr. Bahir Hadi — Consultant Surgeon, PhD
Mucus in stool: When is it normal - and when should it be investigated?
The bowel naturally produces 3-5 ml of mucus per 24 hours to lubricate the stool and protect the mucosa [1]. Visible mucus in the stool can therefore be entirely normal, but a sudden increase, mucus with blood, or mucus combined with a change in bowel habit should always be evaluated - especially in adults over 40.
What is bowel mucus?
Mucus (mucin) is secreted by goblet cells in the bowel mucosa and forms a protective layer against bacteria, acid and digestive enzymes. The amount naturally increases with:
- Constipation (slower passage = more mucus)
- Diarrhoea (acute secretion to protect the mucosa)
- Dehydration
- Pregnancy
Common (benign) causes
| Cause | Typical signs |
|---|---|
| Irritable bowel syndrome (IBS) | Mucus + bloating, alternating stool, abdominal pain relieved by defecation |
| Hemorrhoids | Mucus + fresh red blood, possibly prolapse, itching |
| Anal fissure | Mucus + pain on defecation, slight bleeding |
| Chronic constipation | Mucus around hard stool |
| Gastrointestinal infection | Acute mucus + diarrhoea, possibly fever - typically Salmonella, Campylobacter, Shigella |
Serious causes requiring prompt work-up
Mucus in the stool can also be an early sign of:
- Inflammatory bowel disease (IBD) - ulcerative colitis and Crohn's disease often present with mucus + blood + diarrhoea.
- Intestinal polyps - particularly large villous adenomas can secrete large amounts of mucus.
- Colorectal cancer - mucus + blood + altered bowel habit for >6 weeks is an alarm symptom.
- Diverticulitis - mucus + left-sided pain + fever.
- Rectal prolapse - continuous mucus/leakage.
When should you see a doctor?
Contact your GP promptly if you have:
- Mucus + visible blood in the stool
- Mucus with altered bowel habit for more than 4 weeks (more frequent, looser, thinner)
- Mucus + unintentional weight loss
- Mucus + abdominal or night-time pain
- Age >50 without previous evaluation
- Family history of colorectal cancer or IBD
How mucus in the stool is investigated
- History and stool diary - frequency, consistency (Bristol scale), blood, pain.
- Stool samples - F-calprotectin (distinguishes IBS from IBD), F-Hb (immunochemical blood test), possibly culture and parasites.
- Blood tests - CRP, haemoglobin, ferritin, leukocytes.
- Colonoscopy - gold standard for alarm symptoms, age >50, or raised calprotectin/F-Hb [2].
- Sigmoidoscopy - may suffice for isolated rectal symptoms.
Treatment
Treatment depends entirely on the cause:
- IBS: dietary modification (FODMAP), fibre regulation, possibly antispasmodics.
- Hemorrhoids: dietary fibre, band ligation, possibly surgery.
- IBD: medical treatment by a gastroenterologist (5-ASA, immunomodulators).
- Polyps: polypectomy during colonoscopy.
- Colorectal cancer: surgery in collaboration with oncology.
Treatment at Kirurgen.dk
We offer rapid work-up with colonoscopy and sigmoidoscopy under the public health insurance scheme. See also our articles on rectal bleeding and intestinal polyps.
References
- Johansson MEV, Sjövall H, Hansson GC. The gastrointestinal mucus system in health and disease. Nat Rev Gastroenterol Hepatol 2013;10(6):352-61.
- Rao SSC, Bharucha AE, Chiarioni G, et al. Anorectal disorders. Gastroenterology 2016;150(6):1430-42.
- Lacy BE, Mearin F, Chang L, et al. Bowel disorders (Rome IV). Gastroenterology 2016;150(6):1393-407.
- Vasen HFA, et al. Revised guidelines for the clinical management of Lynch syndrome. Gut 2013;62(6):812-23.
More on this topic at Kirurgen.dk
Category: Gastrointestinal