LOOKING AT THE SMALL INTESTINE IN CROHN'S DISEASE

In Crohn's disease (and almost every disease), tests are used to 

• Diagnose the disease (to make sure that's the cause of the problem)
• See how bad it is (is it mild or worse)
• Determine treatment options and direct their use 
• Monitor the disease and treatment progress

In Crohn's disease, the problems can be anywhere along the gastrointestinal tract, and even outside it. Blood and stool tests aren't specific enough to diagnose the problem, but they often can give a general idea about how bad it is. As a result, they can be used to monitor the disease and its treatment.   

Colonoscopy can be used to evaluate all 4 of the testing needs listed, but only if the disease is in the large intestine (the colon) or the very end of the small intestine (the terminal ileum). There are several problems:

• Part of the disease may be higher in the small intestine. In children, teenagers and young adults, Crohn's disease is in the small intestine 70% of the time; and 30% of the time it is only in the small intestine. We are still not sure how often it is just in the small intestine in adults. But in a small study of 80 adults with suspected Crohn's disease (Leighton and others, including Dr. Stan, Clinical Gastroenterology and Hepatology, 2014), 14% of adults had the diagnosis made in the small intestine by the pill camera where a colonoscopy couldn't reach.  
• Colonoscopies are done with sedation and require the bowel to be clean in order to see it
• Colonoscopies are unpleasant and take time away from work or other activities
• Most people do not want to undergo colonoscopy, if they can avoid it, to monitor their disease activity and treatment progress. 

As a result, most people prefer alternatives, though a colonoscopy in the beginning is important, so that biopsies can be taken, and important to be repeated to look for worsening disease or cancer. 

Alternative Procedures

CT Scans can evaluate the small intestine. The patient must drink or be given contrast material to drink so that the intestine can be well seen. But CT scans expose patients to radiation that adds up if many CT scans or other X-rays are done over the years. That's why now they are usually used  in emergencies, when someone can't tolerate one of the other procedures or when an MRI can't be done.

MRIs, also called MREs, when the patient drinks contrast material to "light up" the intestine, shows the intestine and the surrounding tissues. 

• They do show disease in the lower small intestine and colon very well. 
• They can show narrowing in the intestine (strictures), most fistulas and abscesses. 
• They do not show early disease until the bowel wall is thickened and they are not helpful in showing disease in the upper part of the small intestine (often because the disease there is usually surface ulcers until late in the course of the disease.
• They can take a long time of laying in one position without moving
• They do not expose anyone to radiation
• They do not require a clean bowel (no preparation before the procedure, other than not eating for a short while
• They can't be used when someone has metal in their body (braces, replacement parts, surgical clips)      

Pill cameras are literally pill-sized cameras, the size of a jelly bean. Most teens and adults can swallow one pretty easily (a 4-year-old who takes large vitamins swallowed one sipping water). They have lights, batteries and cameras. They can take pictures as they move through the gastro-intestinal tract. The photos are transmitted to a belt that the person wears. The pill is pooped out, usually the same day.

• Pill cameras can take clear pictures of the small intestine, but now a Crohn's Capsule (already released in Europe) can take pictures of the small and large intestine at the same time. Pill cameras may not see the stomach and esophagus well.
• They can detect early and more advanced disease.   
• Someone can go to work during the procedure which lasts 8-12 hours.
• They do not need sedation or expose anyone to radiation.
• They have been approved for repeat exams to check on the disease and guide treatment.
• They do require a clean bowel preparation with a mild laxative the night before, so that any sores or disease activity can be seen. 
• They can get stuck in a section of narrowing (stricture). That is rare (2-5% of patients with known Crohn's disease). Someone who is known to have Crohn's disease should have a test before to make sure that the capsule can get through. 

Sometimes two of the procedures may be recommended together. An MRE to look for strictures and the area around the intestine and a pill camera to look at the upper intestine, for example. The important part is making sure that the bowel is seen very well and that the disease at that point is fully understood in order to guide treatment.