Ulcerative colitis (UC) is a chronic inflammatory disease of the colon with a prevalence of 35-100 per 100,000. The age of onset has two peaks, one in the second to fourth decades and the other in the sixth and seventh decades of life. Women are 30 per cent more likely to develop UC.
The aetiology is not yet fully understood but it is considered to be autoimmune. Some 20 per cent of sufferers have at least one family member with inflammatory bowel disease.
Smoking appears to reduce the incidence of the disease but ex-smokers have a higher incidence than those who have never smoked, leading to the theory that quitting may be a trigger. Other triggers for onset or relapse include NSAIDs and gastroenteritis.
A number of extra-intestinal conditions are linked with active UC including: erythema nodosum; episcleritis; uveitis; arthropathy; mouth ulcers and pyoderma gangrenosum. Other conditions, such as sacroileitis, ankylosing spondylitis, uric acid renal stones and sclerosing cholangitis may occur independently of the activity of the colitis.
Long-term UC is associated with an increased risk of colo-rectal cancer. The risk is 2 per cent in the first 10 years, 8 per cent over 20 years and 18 per cent over 30 years duration.
Differential diagnoses include: Crohn's disease; infectious colitis, ischaemic colitis, pseudomembranous colitis and irritable bowel syndrome (IBS).
The characteristic features of UC are bloody diarrhoea, urgency and tenesmus. Colicky abdominal pain may occur, although severe pain is generally limited to those with advanced colitis. Bloody diarrhoea may not be present in mild cases involving distal colitis.
Other differential diagnoses may have similar features but the history may be helpful in differentiating the aetiology.
The absence of bloody diarrhoea, systemic upset and night-time symptoms suggests IBS, as does alternating diarrhoea and constipation.
Recent antibiotic use increases the risk of Clostridium difficile and overseas travel may point to infectious colitis. Older patients with a history of vascular disease are more likely to have ischaemic colitis.
Abdominal examination may reveal tenderness or distension. Marked tenderness, guarding and absent bowel sounds may indicate severe disease or toxic megacolon. Increased bowel sounds and distension could be caused by stricture formation. A rectal examination may show bloody discharge/diarrhoea.
A general examination may reveal raised temperature and pulse, which are associated with severe disease. Clubbing and weight loss increase the likelihood of UC but their absence does not rule it out. Patients should also be examined for any UC-associated diseases.
Investigations include stool examination for parasites and stool culture (including testing for C difficile); an ESR and/or CRP may detect systemic inflammation. An FBC, U&E and albumin can detect chronic blood, protein or electrolyte loss from the bowel. Radiological investigations are not recommended as routine by the British Society of Gastroenterology.
The investigation of choice is endoscopy plus multiple biopsies. Caution is needed in severe disease as perforation is a recognised complication. Even with endoscopy, the distinction between UC and Crohn's disease may be difficult.
Distinguishing features of UC include diffuse contiguous spread (always involving the rectum), the absence of fistulae, and inflammation confined to the mucosa.
Treatment depends on the severity and location of the colitis. Less than four stools a day with no systemic disturbance and normal ESR/CRP is considered mild. More than six stools per day plus systemic disturbance is considered severe.
The treatment has two phases. The first is to induce recovery; the second is to maintain remission.
In mild-to-moderate proctitis or left-sided disease, first-line therapy is topical mesalazine (suppositories or enemas). Topical steroids are less effective. If first-line therapy fails then oral steroids can be introduced.
In diffuse, mild-to-moderate disease, oral mesalazine is first line, with oral steroids reserved for non-responders.
Patients with severe disease, suspected toxic megacolon, or who fail to respond to oral steroids in two weeks, require admission. Treatment for these patients includes IV steroids, azathioprine, ciclosporin and infliximab.
Reasons for colectomy
Patients who develop toxic megacolon or fail to respond to IV corticosteroids require colectomy. Others patients may require colectomy for persistent non-acute disease. Overall, a quarter of patients eventually have a colectomy.
Lifelong maintenance therapy with oral or topical mesalazine is recommended to maintain remission. It offers some protection against cancer. Alternatives include azathioprine or steroids. With long-term steroids, osteoporosis screening and prevention may be required.
In view of the increased risk of colorectal cancer, patients who have not had a colectomy should receive screening colonoscopies starting 10 years after the onset of pancolitis or 15-20 years after the onset of left-sided disease. Follow-up colonoscopies should be at three-year intervals.
Dr Spinks is a GP in Strood, Kent