Diagnosing Inflammatory Bowel Disease


Transcript: Miguel Regueiro, MD: Let's move to diagnosis and treatment, and Jessica, I'm going to start with you on this. In terms of how to diagnose IBD [inflammatory bowel disease], a topic that we could probably spend several hours on, but in terms of how you look at symptoms, blood work, imaging, and endoscopy, give us your overall approach to diagnosing IBD.

Jessica R. Allegretti, MD, MPH: As you mentioned, you're going to be using a whole host of factors when you're working up a patient. There's not just a single test that says this patient has IBD, so it's important to remember that. Always start with a good history. You want to be asking your patients about diarrhea, rectal bleeding, urgency, tenesmus. Are they waking up from sleep to have bowel movements? All of these are clinical clues that there's a more organic process going on. Signs of obstruction, distention, and vomiting, and then I always ask about potential signs for fistula complications. Are they having air in their urine or air passing from the vagina? Things that patients might not even think to tell you. When you are doing laboratory assessments, you're looking for signs of systemic inflammation, CRP [C-reactive protein] or ESR [erythrocyte sedimentation rate], as well as signs of anemia, generally speaking.

There are other laboratory tests that people can use. There are the p-ANCA [perinuclear antineutrophil cytoplasmic antibodies] and p-ASCA [perinuclear anti-Saccharomyces cerevisiae antibodies] assays. P-ANCA has been associated with ulcerative colitis and p-ASCA with Crohn disease. I can tell you in my own personal practice [at Brigham and Women’s Hospital], I don't tend to rely on these assays when I'm distinguishing ulcerative colitis from Crohn disease or working people up, but they are available. I don't particularly find them helpful; I use everything else we're talking about right now to make the diagnosis.

The most important step, though, is once you have a patient for whom you are suspecting IBD based on what we've discussed, is that you need to do a full endoscopic examination, and that includes a full colonoscopy with TI [terminal ileal] intubation to get an assessment of the small bowel as well. Before you start treatment, you want to stage this person. You want to know where their inflammation is and how deep those ulcers are as we have already been discussing. I always conclude with imaging of the small bowel as well. I want to ensure that I know exactly where this person has disease to craft the best treatment strategy for them, whether that's with MR [magnetic resonance] enterography, CT enterography, or some of the ultrasound techniques that are emerging. Once we put all that together, radiology, laboratory assessments, as well as clinical findings, then you're able to make the diagnosis.

Miguel Regueiro, MD: A history and physical, and then a multimodality approach to diagnosis. Marla, moving to you for a differential diagnosis. The group on the line here are all at tertiary referral centers, but these patients, as you know in pediatrics, often see their pediatrician first or, in adults, the family doctor, the primary care physician, or are referred to GI [gastroenterology] for general symptoms. What's your breakdown for differential diagnosis for somebody coming in where IBD might be on the list? What other things do you think about?

Marla C. Dubinsky, MD: One of the things to also note is that there's often a diagnostic delay for our patients being diagnosed. I want to feed off of what Jess was saying. She's asking for more classic alarm or red flag symptoms and signs because that'll move them to the front of the queue, but there are still a lot of patients with Crohn disease in particular who have been told to change their diet, have been diagnosed with irritable bowel syndrome [IBS], told to just deal with it or take more MiraLAX, whatever is on the table. There's often a lot of diagnostic delay, sometimes up to 2 years in patients with Crohn disease. That's probably our biggest differential in terms of patients presenting with some bloating, some fatigue, some intermittent loose stools, right lower quadrant pain; various bloating is one of the biggest symptoms that gets attributed to IBS, for example.

We're often trying to figure out, is this infection? Is this organic or functional versus nonfunctional? For colitis, it’s do you have an infectious cause of your bloody diarrhea and name the list of the organisms that could cause that, especially if you've traveled recently or been exposed to antibiotics recently. Even just having intermittent diarrhea, without blood, that still defaults to an infectious cause. At the end of the day, yes, there's a whole laundry list in our books of differential diagnosis, but let's be practical about what patients come to us being diagnosed as and where the biggest delay is.

One thing that people underestimate is small intestinal bacterial overgrowth [SIBO]. I know it's not typically all over the map with our patients, but I would tell you that patients are often told they have some form of IBD or IBS, and we're missing the fact that they've had 10 courses of antibiotics for acne, or they've had recurrent urinary tract infections and have been on multiple courses. We're underestimating small intestinal, or SIBO, in our differentials as well. By the time they get to us, they've been through the gamut of differential diagnoses. I don't know if there's specifically something you want to go through in the textbook of differential, but these are the most important 2 concepts that we often lose sight of.

Miguel Regueiro, MD: We won't go through the medical school list of differential diagnoses. I like the way you broke it down. A lot of our patients are told they've had irritable bowel syndrome for years. That was a very important point. Celiac, small intestinal bacterial overgrowth, some of these patients come in with infections if it's an acute process. Those are probably some good highlights. We could get into ischemic colitis, diverticulosis, or some of the others, but that’s probably the good list and oftentimes is what leads to a delay in diagnosing Crohn disease or ulcerative colitis because they're assumed to have IBS.

William J. Sandborn, MD: The other interesting thing about differential diagnosis is that Marla was talking predominantly about before you're diagnosed, but there's the whole differential diagnosis of symptoms after you're diagnosed, especially in Crohn disease. That would also include SIBO. It includes bile acid diarrhea, which you can now objectively diagnose, the liberal use of 72-hour fecal fat in patients who've had a lot of operations. Those things are often forgotten. You're not done with the differential diagnosis once the patient's diagnosed. It's not all inflammatory Crohn disease.

Miguel Regueiro, MD: You bring up a good point because, for a lot of our patients, sometimes when we see patients in the office we've done a great job at healing the mucosa, treating their inflammation, yet they're still having symptoms. Bill, you nailed it. Part of the IBD-ology that we all see in our clinics is also the noninflammatory part, so bile salts, fat, some other malabsorptive problems, vitamin deficiency, so I completely agree.

Transcript Edited for Clarity

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