Diagnosing Crohn's can be difficult because its symptoms are similar to those of other conditions. Here's how your doctor will determine if you have it.
By Lisa Baertlein
It's believed roughly 500,000 Americans have Crohn's disease, a chronic condition that causes inflammation of the digestive tract. If you have abdominal cramps or pain a few hours after eating, frequent diarrhea, bleeding from your rectum, weight loss, night sweats, or a recurrent fever, you may be one of them. Diagnosing Crohn's can be especially challenging because its symptoms are so similar to those of several other conditions, but a visit to your doctor is the first step toward diagnosis and treatment.
Crohn's vs. Other, Similar Conditions
Because there is no single test that can determine whether or not you have Crohn's, your doctor will probably order a combination of tests to rule out other conditions with similar symptoms. Such conditions include:
An experienced gastroenterologist can often eliminate a diagnosis of irritable bowel syndrome relatively quickly because people with IBS do not usually experience pain during bowel movements, and their symptoms go away while they're sleeping. This condition also differs from Crohn's in that it is not commonly associated with significant weight loss, anemia, rectal bleeding, stool blood, or recurring fever — a sign of inflammation.
When trying to rule out celiac disease, your doctor may ask how you react to certain foods. Gluten, which is found in wheat, barley, rye, and possibly oats, damages the small intestine in people with celiac disease, and the resulting symptoms often mimic those of Crohn's. A diagnosis of celiac disease is confirmed when blood tests show elevated levels of immunoglobulin A (IgA), antitissue transglutaminase (anti-tTG) antibodies and antiendomysium antibodies (AEA).
Ulcerative Colitis and Diverticular Disease
Distinguishing among Crohn's, ulcerative colitis, and diverticular disease can be more difficult and time-consuming and can involve more tests. Your physician will take a detailed history and do a complete physical exam, which may include checking your abdomen for tenderness or masses and checking your rectum for hemorrhoids, tears, or narrowing. Preliminary lab work will probably include blood, stool, and urine tests to check for any internal bleeding, infection, or inflammation.
Your doctor may also order a test called the erythrocyte sedimentation rate (ESR), or SED rate, to find out whether inflammation has made your red blood cells sticky and prone to settling more quickly than usual. A higher-than-normal SED rate and an elevated C-reactive protein level provide confirmation of systemic inflammation — the hallmark of inflammatory bowel diseases, such as Crohn's and ulcerative colitis.
Blood antibody testing, though not 100 percent reliable, can help a doctor distinguish between Crohn's and ulcerative colitis, since people with Crohn's tend to be positive for the anti-Saccharomyces cerevisiae antibody, or ASCA, but negative for perinuclear antineutrophil cytoplasmic antibody, or pANCA. The opposite is usually true in people suffering from ulcerative colitis, which causes inflammation and ulcers in the lining of the colon and rectum.
General Diagnostic Techniques
If you are suffering from frequent diarrhea and abdominal cramps — and laboratory test results suggest that more investigation is needed — doctors have many ways to "see" what's happening in the gastrointestinal (GI) tract. X rays, computed tomography (CT) scans, ultrasounds, magnetic resonance imaging (MRI), and small scopes inserted through the mouth, nose, or anus can all pinpoint damage or abnormalities in the gut. Since some of the tests can be uncomfortable, painful, or embarrassing, it is important that you make your doctor aware of any physical or emotional concerns you may have and ask whether anything can be done to ease your worries.
Ordinary abdominal X rays are often used when a doctor suspects a small bowel obstruction, which occurs when inflammation thickens intestinal walls, making it difficult for food to pass through.
Barium enemas are commonly used to diagnose and evaluate the severity of Crohn's because they allow doctors to view the areas most affected by the disease. During the procedure, barium is placed in the intestines through a tube inserted in the rectum. The barium — a chalky, metallic white liquid — coats the inside of the GI tract and produces clear X-ray images. Air may also be used to expand the colon and further improve the images. This test is designed to help find ulcers, damage from inflammation, or narrowing of the bowel. Depending on the circumstances, your doctor may consider performing one of two other, similar tests. A test of the upper gastrointestinal tract requires that you swallow a barium-based liquid before having an X ray. Another procedure, called enteroclysis, delivers a barium-based liquid through a tube that's inserted through the nose and extends to the beginning of the small intestine — it can help show abnormalities in that area.
Computed tomography, or CT scanning, uses a series of X rays to create a detailed picture of the body's anatomy. CT scans can help your physician pinpoint inflammation, scarring, obstructions, infection, tears, and fistulas, which can result in abnormal connections between different parts of the intestine.
Magnetic resonance imaging, or MRI, uses magnetic fields to make an image of the body. MRIs are a particularly accurate tool for evaluating perianal (meaning "around the anal area") complications. Such complications include fissures, ulcers, abscesses, and fistulas, which may leak pus, mucus, or stool from the intestines through a hole near the anus.
Endoscopic Diagnostic Techniques
Your doctor may choose to run endoscopic tests, which use a camera inside a lighted, flexible tube to relay pictures to a video monitor. Such tests are usually used at the time of diagnosis to measure the extent of damage from inflammation.
Sigmoidoscopy is the most commonly performed endoscopic test used to confirm a Crohn's diagnosis. During the quick, 10- to 20-minute office procedure, a flexible sigmoidoscope is inserted into the rectum to examine the lower intestine, also known as the sigmoid colon, or to take a tissue sample for testing.
Colonoscopy is a 30- to 60-minute procedure that can be done in a doctor's office, outpatient GI facility, or a hospital. A lighted colonoscope is inserted into the rectum, allowing the doctor to get a view inside the rectum, the entire colon, and the end of the small intestine, known as the terminal ileum. This test is useful in confirming Crohn's of the ileum and for collecting samples of tissue for colon cancer screening. While sedation is not regularly used during sigmoidoscopy, it is often given to people undergoing colonoscopy.
Esophagogastroduodenoscopy, or EGD, may be used to see the esophagus, the stomach, and the first part of the small intestine if Crohn's of the upper gastrointestinal tract is suspected. The test, in which a scope is inserted through the mouth, usually takes 10 to 20 minutes.
Capsule endoscopy, in which a patient swallows a capsule-encased camera that feeds images to a recorder worn on his or her belt, is helpful in diagnosing Crohn's in the small intestine, according to recent studies. However, it is not recommended when a bowel obstruction is suspected or present, or for patients with areas of narrowing.
Living With Crohn's
Since Crohn's is a chronic disorder that can worsen over time, getting the right diagnosis is a worthwhile investment — even if it means going through some uncomfortable testing procedures. A proper diagnosis will help you and your doctor decide on the best treatments to improve your daily life, ease your symptoms, and potentially bring on remission.