Diagnosis

Clinical Presentation

Ulcerative colitis (UC) is a chronic inflammatory disease of the rectum and colon, with contiguous lesions characterized by superficial infiltration of the bowel wall with inflammatory white cells. The lesions, comprised of multiple mucosal ulcerations and crypt abscesses, almost always affect the rectum and may extend to the descending and transverse colon and possibly to the entire colon.

Clinically, patients present with one or more of the following signs and symptoms:1

• Bloody diarrhea (with prominent symptoms of rectal urgency and tenesmus)
• Abdominal pain
• Fever
• Anorexia
• Weight loss
• Elevated heart rate
• Hypotension
• Pallor

While approximately 28% of patients have only one acute episode that resolves and never recurs, 5% have an unremitting course and the majority of patients (65%) experience repeated episodes of acute disease interspersed with periods of inactive disease (remission). Approximately 37% of patients develop severe, refractory UC and ultimately require surgery.2,3

With the initial attack, approximately 44% to 49% of patients present with proctitis or proctosigmoiditis, 36% to 41% have disease extending beyond the rectum, and 14% to 30% have pancolitis.3 Examination reveals diffuse mucosal inflammation. Disease progresses distally to proximally in a symmetrical, circumferential, and uninterrupted pattern involving parts or all of the large intestine.4

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Diagnostic Workup

Rule out colon cancer, adenocarcinoma, and rectal cancer. Other possible conditions to be considered in differential diagnosis:

• Crohn's disease (CD)
• Infectious colitis
  (both of the above findings correlate with disease activity)
• Ischemic colitis (particularly but not exclusively in elderly patients)
• Radiation colitis
• Collagenous colitis
• Lymphocytic colitis

Perform stool studies to exclude other causes.

Conduct lab studies to detect:

• Anemia (i.e., hemoglobin < 14 g/dL in males and < 12 g/dL in females)
• Thrombocytosis (i.e., platelet count > 350,000/mcL)
• Elevated sedimentation rate (>0-33 mm/h)
• Elevated C-reactive protein (> 100 mcg/L)
• Hypoalbuminemia (i.e., albumin < 3.5 g/dL)
• Hypokalemia (i.e., potassium < 3.5 Eq/L)
• Hypomagnesemia (i.e., magnesium < 1.5 mg/dL)
• Elevated alkaline phosphatase (i.e., > 125U/L may indicate primary sclerosing cholangitis; usually > 3 times the upper limit of the reference range)

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Imaging Studies

• A recent study has indicated that low-field MRI (T-2 and T-2 SI) compares favorably with radiography, endoscopy, leucocyte scintigraphies, double-contrast barium enemas, and surgery in the detection of colonic disease activity.5
• Barium enemas can be performed safely in mild cases but may precipitate toxic megacolon in severe cases.
• Transabdominal bowel sonography (TABS) may be helpful in the diagnosis of inflammatory bowel disease (IBD) but it cannot distinguish between UC and CD.
• Abdominal radiographs may show colonic dilatation suggestive of toxic megacolon in severe cases as well as perforation, obstruction, or ileus.
• Radionuclide scan may be helpful in diagnosing disease activity and extent when barium enema or colonoscopy is contraindicated.
• CT scan adds little in the diagnosis of UC. It can show thickening of colonic wall and biliary dilatation suggestive of sclerosing cholangitis.

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Procedures and Histologic Findings

UC typically presents with a relatively uniform, continuous reaction in the colonic mucosa.

• Flexible sigmoidoscopy can diagnose UC and may be sufficient when knowledge of extent of disease is not needed to establish treatment.

Colonoscopy with biopsy confirms a diagnosis of UC and is useful for documenting extent of disease, monitoring disease activity and dysplasia/cancer surveillance; however, caution is required in patients with severe disease because of potential complications such as perforation.

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References

1. Hanauer SB. Inflammatory bowel disease. N Engl J Med. 1996;334;13:841-848.
2. Chinyu Su, Lichtenstein GR. Diagnosis of Crohn's disease: a wolf in sheep's clothing? Am J Gastroenterol. 2000;95(12):3345-3350.
3. Farmer RG. Easley KA, Rankin GB. Clinical patterns, natural history and progression of ulcerative colitis. A long-term follow-up of 1116 patients. Dig Dis Sci. 1993;38(6):1137-1146.
4. Davis RL, Bohlke K. Measles vaccination and inflammatory bowel disease: controversy laid to rest? Drug Saf. 2001;24(13):939-946.
5. Madsen SM, Thomsen HS, Munkholm P, et al. Inflammatory bowel disease evaluated by low-field magnetic resonance imaging. Comparison with endoscopy, 99mTc-HMPAO leucocyte scintigraphy, conventional radiography, and surgery. Scand J Gastroenterol. 2002;37(3):307-316.

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