Pathology of ulcerative colitis explained

Ulcerative colitis affects the lining of the rectum and colon. An overactive immune response creates inflammation in that surface layer, which can make it fragile and form open sores. Inflamed lining absorbs water less effectively and may contract more often, producing frequent or urgent bowel movements. Irritation can also cause cramping or abdominal pain, while bleeding and reduced intake may leave someone tired. Symptoms can settle for a period and then return in a flare. The extent and activity of inflammation vary between people, so symptoms alone cannot show how much bowel lining is affected.

A GP or gastroenterology clinician may ask about stool frequency, urgency, blood, pain, weight and symptoms outside the bowel. Assessment can include blood or stool tests and sometimes a camera examination of the bowel with tissue samples. Treatment is selected to calm inflammation and maintain remission; take it consistently even when symptoms improve unless your clinician changes the plan. Keep a record of bowel changes, drink enough fluid and ask before using anti-inflammatory pain medicines or anti-diarrhoeal medicines. Colorectal cancer screening may be discussed as part of longer-term follow-up.

Get urgent medical advice for heavy rectal bleeding, severe or rapidly worsening abdominal pain, a swollen abdomen, repeated vomiting, faintness, confusion, high fever or inability to keep fluids down. A sudden increase in bloody diarrhoea can represent a serious flare. Seek prompt review as well if you are passing very little urine or becoming unusually weak, because dehydration can develop quickly.

Ask which tests are needed to confirm inflammation, how you will recognise a flare, when treatment should be adjusted, and whether you need specialist follow-up. Discuss food and medicines that worsen your symptoms, vaccination advice, and the timing of colorectal cancer screening.