Inflammatory Bowel Disease Part 2

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This week we continue to explore inflammatory bowel disease:

Ulcerative colitis is defined as an inflammatory disease affecting colonic mucosa anywhere from the rectum (ALWAYS involved) to the cecum, causing anything from proctitis (rectum-only) to pancolitis (entire colon); inflammation limited to rectum or left colon is more common than pancolitis. On colonoscopy, the inflammation seen is diffuse, continuous, and confined to the mucosa. The incidence of ulcerative colitis is 2~10/100,000 and prevalence is 35~100/100,000. This makes it more common than Crohn’s disease. Two-thirds of patients have disease onset by age 30, with a second peak after age 50; like Crohn’s disease, the distribution is equal between male and female patients. There is a small hereditary contribution—15% of cases have 1^st degree relative with disease. Risk is LESS in smokers.

The hallmark clinical feature of ulcerative colitis is rectal bleeding. Diarrhea can also be present, as well as abdominal cramps/pain (especially with defecation), tenesmus, urgency, and incontinence; systemic symptoms include fever, anorexia, weight loss, and fatigue. The severity of the colonic inflammation correlates with the symptoms (e.g. stool volume, amount of blood in stool). Patients with ulcerative colitis present with characteristic exacerbations and remissions; 5% of cases are fulminant.

Although there is no single confirmatory test, sigmoidoscopy with mucosal biopsy is often sufficient for diagnosis, but a colonoscopy would be helpful in determining the extent of disease (but contraindicated in severe exacerbation). CT colonography (formerly barium enema) can be done if colonoscopy not possible. Stool culture and microscopy and C. Difficile toxin assay should be done to exclude infectious causes.

The mainstay of treatment is 5-ASA derivatives (suppository and enema form in acute treatment; oral form can be used in maintaining remission) and corticosteroids (IV for acute disease; suppositories/enemas/topical applications can be used for disease distal to splenic flexure) for mild to moderate disease; the use of 5-ASA medications such as sulfasalazine or mesalamine may decrease rate of colorectal cancer. Immunosuppressants (e.g. 6-MP) and biologics (e.g. infliximab) are used in hospitalized patients with severe ulcerative colitis; biologics can also be used for outpatients with moderate to severe disease, particularly those that are steroid-unresponsive or steroid-dependent. Azathioprine can also be used in those who are steroid-dependent, but they are most commonly used to maintain remission while corticosteroids are being withdrawn; when given together with biologics, azathioprine increases the efficacy of biologics and decreases the likelihood of tolerance to biologics (around 10% chance/year). Diet change is of little value in decreasing inflammation but may alleviate symptoms. Anti-diarrheal medications are generally not used in ulcerative colitis. When all else fails, colectomy is a curative option; bowel continuity can be restored with ileal pouch-anal anastomosis (IPAA). Other indications of colectomy include toxic megacolon, uncontrollable bleeding, pre-cancerous changes detected by endoscopy/colonoscopy/biopsy, overt malignancy, or inability to taper corticosteroids.

Complications of ulcerative colitis are similar to that of Crohn’s disease, except that there are more liver problems involved in ulcerative colitis (especially primary sclerosing cholangitis in men). There is a greater risk of colorectal cancer in ulcerative colitis; the risk increases with duration and extent of disease and also increases with active mucosal inflammation and development of sclerosing cholangitis. Thusly, regular colonoscopy and biopsy in pancolitis of ≥ 8 years is indicated. Toxic megacolon (traverse colon diameter > 6cm on abdominal x-ray) with immediate danger of perforation is also a major complication! This is lethal and requires immediate treatment using steroids +/- surgery.

A comprehensive list of complications of ulcerative colitis is as follows:

Urinary calculi

Liver problems

Cholelithiasis

Epithelial problems

Retardation of growth/sexual maturation

Arthralgia

Thrombophlebitis

Iatrogenic complications

Vitamin deficiencies

Eye problems

Colorectal cancer

Obstruction

Leakage (perforation)

Iron deficiency

Toxic megacolon

Inanition (wasting)

Strictures

In patients with only proctitis, the disease usually runs a benign course. However, most patients present in chronic relapse pattern. More colonic involvement in the first year of onset correlates with increased severity of attacks and increased colectomy rate. Post colectomy most patients can have normal life expectancy.

The biggest difference between Crohn’s disease and ulcerative colitis is that Crohn’s disease can affect any part of the GIT where as ulcerative colitis is limited to the large intestines.

And as promised... the bonus chart of extra-intestinal manifestations of IBD!