Inflammatory Bowel Disease

Tests

The diagnosis of an IBD is primarily made with non-laboratory tests, but laboratory testing is an important tool for ruling out other causes of diarrhea, abdominal pain, and colitis. These causes can include viral or bacterial infections, parasites, medications, abdominal or pelvic radiation, colon cancer, and a variety of other chronic conditions, such as celiac disease and cystic fibrosis.

Laboratory Tests
Tests that may be ordered to rule out other causes of diarrhea and inflammation include:

• Stool culture to look for bacterial infection
• O&P (Ova and parasite) to detect parasites
• Clostridium difficile to detect toxin created by bacterial infection; may be seen following antibiotic therapy
• Fecal occult blood to look for blood in the stool
• Stool WBC to detect white blood cells in the stool
• Celiac Disease tests

Tests that are not specific for IBD but may be done to detect and evaluate the inflammation and anemia associated with IBD include:

• ESR (erythrocyte sedimentation rate) to detect inflammation
• CRP (C-reactive protein) to look for inflammation
• CBC (complete blood count) to check for anemia

Calprotectin is a protein associated with inflammation. Its use as an inflammatory marker to help diagnose and monitor IBD when measured in stool (fecal) samples is gaining attention. It may prove to be a useful test in predicting relapses in IBD patients.

There are several blood tests that detect markers associated with IBD. Some of these are antibodies the body produces against certain bacterial antigens. They are not widely used clinically but may sometimes be ordered to help differentiate between UC and CD. These tests are not sensitive or specific enough to diagnose either condition, but they may give the doctor additional information. They include:

• pANCA (Perinuclear anti-neutrophil cytoplasmic antibody) is found in about 50% of those with UC, but only about 5% to 20% of those with CD.
• ASCA (Saccharomyces cerevisiae antibodies), IgG and IgA. ASCA IgG and/or IgA are found in about 40% to 50% of CD patients. ASCA IgG is found in about 20% of those with UC. ASCA IgA is found in less than 1% of those with UC.
• Anti-CBir1 (Clostridium species antibodies), found to be associated with about 50% of Crohn’s disease cases.
• Anti-Omp C (Escherichia coli antibodies), associated with rapidly progressing Crohn’s disease.
• Anti-I-2 (Pseudomonas fluorescens antibodies)

Non-Laboratory Tests
These tests are used to help diagnose and monitor UC and CD. They can be used to look for characteristic changes in the structure and tissues of the intestinal tract and to detect blockages. Care must be taken during an acute attack or flare-up of an IBD as there is a slight chance of perforating the bowel during testing.

• X-ray (abdominal), barium contrast dye allows an evaluation of the intestines.
• Sigmoidoscopy, a slender tube is used to examine the last 2 feet of the colon.
• Colonoscopy, a slender tube is used to examine the entire colon; it includes a light and camera and can be used to take biopsies.
• Biopsy, tissue samples from the colon that are evaluated for inflammation and abnormal changes in cell structures.