General

The initial diagnostic workup for ulcerative colitis includes the following:

• A complete blood count is done to check for anemia; thrombocytosis, a high platelet count, is occasionally seen
• Electrolyte studies and renal function tests are done, as chronic diarrhea may be associated with hypokalemia, hypomagnesemia and pre-renal failure.
• Liver function tests are performed to screen for bile duct involvement: primary sclerosing cholangitis.
• X-ray
• Urinalysis
• Stool culture, to rule out parasites and infectious causes.
• Erythrocyte sedimentation rate can be measured, with an elevated sedimentation rate indicating that an inflammatory process is present.
• C-reactive protein can be measured, with an elevated level being another indication of inflammation.

Although ulcerative colitis is a disease of unknown causation, inquiry should be made as to unusual factors believed to trigger the disease. Factors may include: recent cessation of tobacco smoking; recent administration of large doses of iron or vitamin B6; hydrogen peroxide in enemas or other procedures.

Endoscopic

Biopsy sample (H&E stain) that demonstrates marked lymphocytic infiltration (blue/purple) of the intestinal mucosa and architectural distortion of the crypts.

The best test for diagnosis of ulcerative colitis remains endoscopy. Full colonoscopy to the cecum and entry into the terminal ileum is attempted only if diagnosis of UC is unclear. Otherwise, a flexible sigmoidoscopy is sufficient to support the diagnosis. The physician may elect to limit the extent of the exam if severe colitis is encountered to minimize the risk of perforation of the colon. Endoscopic findings in ulcerative colitis include the following:

• Loss of the vascular appearance of the colon
• Erythema (or redness of the mucosa) and friability of the mucosa
• Superficial ulceration, which may be confluent, and
• Pseudopolyps.

Ulcerative colitis is usually continuous from the rectum, with the rectum almost universally being involved. There is rarely peri-anal disease, but cases have been reported. The degree of involvement endoscopically ranges from proctitis or inflammation of the rectum, to left sided colitis, to pancolitis, which is inflammation involving the ascending colon.

Histologic

Biopsies of the mucosa are taken to definitively diagnose UC and differentiate it from Crohn's disease, which is managed differently clinically. Microbiological samples are typically taken at the time of endoscopy. The pathology in ulcerative colitis typically involves distortion of crypt architecture, inflammation of crypts (cryptitis), frank crypt abcesses, and hemorrhage or inflammatory cells in the lamina propria. In cases where the clinical picture is unclear, the histomorphologic analysis often plays a pivotal role in determining the management.