Diagnosing IBS-C: Expert Roundtable Part 1

Diagnosing irritable bowel syndrome with constipation can be challenging. In this video, Drs Anthony Lembo, Brooks Cash, and Megan Riehl discuss the importance and the tests required to make a positive diagnosis rather than a diagnosis of exclusion to ensure proper therapy and reassure patients.

Anthony Lembo, MD, is a professor of medicine at the Lerner School of Medicine at Case Western Reserve at Cleveland Clinic in Cleveland, Ohio. Brooks Cash, MD, is a professor of medicine at Texas A &M School of Medicine and the medical director of the Functional Bowel Center at Baylor Scott & White at Baylor University Medical Center in Dallas, Texas. Megan Riehl, PsyD, is a GI psychologist and an associate professor of medicine and the clinical director of the GI Behavioral Health Program at the University of Michigan in Ann Arbor, Michigan.

Be sure to see Part 2 on this roundtable at https://www.hmpgloballearningnetwork.com/site/gastro/videos/treating-ibs-c-expert-roundtable-part-2

CLINICAL PRACTICE SUMMARY:

Irritable Bowel Syndrome With Constipation (IBS-C)

• Definition, prevalence, and diagnostic criteria (Rome IV): Irritable bowel syndrome with constipation (IBS-C) is a disorder of gut–brain interaction characterized by intermittent abdominal pain or discomfort associated with altered bowel habits, specifically constipation. Using Rome IV criteria, IBS prevalence is ~4–5% in the U.S., increasing to ~8–10% with earlier criteria; approximately one-third of IBS patients have IBS-C. Constipation features include ≥2 of the following: <3 bowel movements/week, straining, manual maneuvers, sensation of obstruction, or hard/lumpy stools (Bristol type 1–2), with symptoms present ≥3 months and onset ≥6 months prior.

• Clinical assessment and workup: IBS-C is diagnosed positively based on symptom criteria and absence of alarm features (e.g., GI bleeding, anemia, family history of colorectal cancer, IBD, or celiac disease). Recommended evaluation includes history, abdominal and digital rectal exam, CBC to assess for anemia, and confirmation of age-appropriate colorectal cancer screening. Extensive diagnostic testing is not routinely recommended due to low yield; targeted tests (e.g., thyroid, calcium) may be considered. Additional physiologic testing (e.g., anorectal motility) is reserved for patients who fail initial therapy.

• Constipation subtypes and management considerations: Constipation may reflect normal transit, slow transit, or pelvic floor dysfunction, the latter affecting ~20–30% of patients with chronic constipation or IBS-C. Nonresponse to laxatives can predict pelvic floor dysfunction, which is typically treated with biofeedback therapy. Distinguishing IBS-C from chronic idiopathic/functional constipation hinges on the presence of abdominal pain; bowel symptoms alone are similar, making the distinction largely semantic for routine clinical care but relevant for pain-focused management strategies.

TRANSCRIPT:

Well, thank you for joining us. We're going to have a discussion today on IBS with constipation. My name is Dr. Anthony Lembo. I'm a professor of medicine at the Lerner School of Medicine at Case Western Reserve at Cleveland Clinic. I'm joined today by two of our colleagues. I'll let them introduce themselves, and then we'll go ahead and start our discussion. 

Hi, I'm Brooks Cash. I'm a professor of medicine at Texas A &M School of Medicine and the medical director of the Functional Bowel Center at Baylor Scott & White at Baylor University Medical Center in Dallas, Texas. It's a pleasure to be here.

Hi, and I'm Dr. Megan Riehl. I'm a GI psychologist at the University of Michigan, where I'm an associate professor of medicine, as well as the clinical director of the GI Behavioral Health Program. And as always, it's great to be the GI psychologist and the whole team approach here to IBS.

Dr Lembo:  Great. So let's go ahead and start our discussion. on irritable bowel syndrome with constipation, a very common disorder, something that we see day in and day out in our practice. I'm sure all of you do as well. Brooks, tell us a little bit about IBSC. How common is it? And any other tidbits you want to tell us about your patients that you've seen?

Dr Cash: Sure. Well, it's a very common problem. You know, there's a wide variety of estimates in terms of just the prevalence of irritable bowel syndrome. And when we mention that term, it is a diagnosis, but it's also a description of symptoms. And so in my parlance and in my mind, when I'm saying to somebody that I think they have irritable bowel syndrome, I'm really describing abdominal pain. And I include the word discomfort along with altered bowel habits. And of course, the altered bowel habits can be run from diarrhea to constipation to a mix of both. Now, specifically when we're talking about irritable bowel syndrome with constipation, we're implying that patients have the abdominal pain and or discomfort as well as constipation symptoms. And that's really about 6 different symptoms and patients should have at least 2 of these symptoms. And those symptoms include infrequent defecation—and that infrequency is typically less than 3 per week; straining, excessive straining to have a bowel movement; having to use manual maneuvers to facilitate defecation; a sensation of obstruction; and hard, lumpy stool, so Bristol stool form scale type 1 or 2. And I think I've got all of those. There may be another one that I dropped out there.  But generally 2 out of those symptoms, along with the abdominal pain and or discomfort. Now, the prevalence of IBS generally really depends on the criteria, the diagnostic criteria that you're looking at, our current Rome 4 criteria.

Prevalence is about 5%, 4 5 % to 5%. Looking at Rome 3 and perhaps some evolving criteria it jumps up to about 8% to 10%, which is kind of the traditional number that we throw out there. In terms of constipation, it's about a third of those patients, roughly. Now, it's going to differ depending on your patient population, but that's generally a rule of thumb. So it's a very common thing that we see both in primary care as well as in specialty care.

And I think it's key that the pain or discomfort has to be associated with the bowel habits. So what IBS is not, because patients come to me all the time saying they were diagnosed with IBS, yet they'll have chronic, unremitting pain, unrelated to physiological function, meaning that it doesn't get worse with eating, it doesn't change with bowel habits. For IBS, we're really talking about an intermittent pain or discomfort, something abdominal; oftentimes people have bloating that's associated with the alteration in bowel habits. So that's sort of a key thing.

Dr Lembo:  Brooks, why do they call it irritable? I mean, is the patient irritable or is it? I was confused why it was called irritable bowel and not something else.

Dr Cash: Unfortunately, I think it's an unfortunate historical term. I think the acronym as well, IBS, often confuses people with IBD as well. So, you know, it was called irritable back in the ‘40s and ‘50s, that was when we started discussing these things. We always use evocative terms like spastic colon and, you know, a number of different types of terminologies, and it just happened to stick. We're now trying to transition away from those types of descriptors with regards to just the global description of functional GI symptoms to disorders of gut -brain interaction, which really meant to evoke and convey more of the global idea of the origins of these symptoms. But I don't have a great answer for where the term irritable came from, other than the patients are irritable. Sometimes the clinicians are too.

But it's that concept of, just as you mentioned, intermittent, bothersome symptoms that really degrade our patients’ quality of life dramatically. And I think that point that you made is really important, that these are typically not constant symptoms, and they do have to beassociated to meet the criteria. They need to be associated, the pain or the discomfort is central, and it needs to be associated with those altered bowel habits.

Dr Lembo:  Yeah. And I mean, for the criteria, like the Rome criteria, which is probably not that important for a clinician, for patients coming to see you, with complaints they probably have pretty frequent complaints but there is a frequency of pain that you need to you know meet at least 3 times per month and a duration because we all get a little bit constipated. I mean who doesn't have occasional cramps with associated bowel habits? But really you have to have symptoms for 3 months with that frequency and the onset of symptoms for at least 6 months really to make sure that this is a chronic problem that that isn't related to an organic disease that may have just come up and be quite severe, which is pretty rare. I mean, how do you exclude organic disease? What do you do when you see a patient? What's your workup, or do you do any workup in these patients?

Dr Cash: Well, I do firmly adhere to the concept of making a positive diagnosis. And what that means is that we use these clinical criteria that have been developed, and the Roome are probably the most widespread and most widely adapted and most widely known. There are other criteria that have been created for irritable bowel syndrome in general, but in this day and age, it's usually the Rome criteria. And if somebody meets the Rome criteria, I exclude alarm features simply by speaking with them. So I asked them if they are passing blood, if they have a family history of organic gastrointestinal disease, such as colon cancer, celiac disease, inflammatory bowel disease. And there are a number of other alarm features.

I do a physical exam of the abdomen as well as the erectile exam. And if patients, A, don't have alarm features and B, don't have an abnormality on their physical exam that makes me want to investigate those abnormalities further, I generally will make a diagnosis of IBS with constipation if they fit those criteria that we discussed. I do a little bit of judicious testing. And when I say a little bit, I mean, I check a CBC to rule out anemia, which is an alarm feature. And I'll chase that down if they have that. I also make sure that they're up to date with their colon cancer screening. Beyond that, we generally don't recommend diagnostic testing, because it doesn't have a high yield. That doesn't make testing for hypothyroidism incorrect to do. And I often will check people's metabolic panels. I'll make sure they're not hypercalcemic and I'll check their thyroid if it hasn't been done, because those can be causes of constipation. The yield of that in terms of studies that have looked at the diagnostic yield in patients with suspected IBS is basically the same as you would get applying it to people who don't have these symptoms. But that's generally my workup.

And then I reserve additional testing, such as testing of the physiology of defecation for patients who don't respond to initial therapeutic interventions.

Dr Riehl: And can I just say how important, certainly the medical workup is reassuring for patients, but how you deliver that diagnosis—that you have, based on the workup that we've done together, IBS with constipation. And here are our next steps. That I think is such a profound, important aspect of the road to feeling better that patients are looking for. And it also can help prevent that additional testing that they may be asking and asking and asking for. Can you do this test? Can you do this one more, one more time? Well, I want to just make sure, which is driven by anxious behaviors because you don't feel well.

So I just wanted to highlight that how you deliver that diagnosis as definitive, not wishy -washy, is tremendously important in moving forward with treatment.

Dr Lembo:  I couldn't agree more. So a confident diagnosis. And again, you should be confident about it, right? Because as you said, we know from lots of studies and from our practice that patients, that there isn't an organic cause that would explain those symptoms, particularly when they're chronic. So it really does depend on the patient presentation. And if someone presents, if it's an older person, new onset symptoms. you know, or progressively worsening, yeah, you know, I might be a little bit more aggressive with that workup, at least once.

But usually patients have had this for many years and it's quite, you shouldn't be doing testing. When do you do an anorectal motility? I mean, we talked about dyssynergia. That's, you know, you talked about the rectal exam. Is that good enough? Is a digital exam good enough? A lot of people may not be doing it in the office as commonly as they probably should. So tell us more about that.

Dr Cash: Well, the digital exam can be very helpful, but like everything, practice doesn't necessarily make perfect, but it certainly increases your skill. So if you rarely do digital rectal exams, then I would say, yeah, it's probably not very helpful. But the more you do, the more normals you feel and the more abnormals you feel, I think it can help discriminate some of these subsets of constipation. And when we think about subsets of just the symptom of constipation. I generally describe it to patients as 3 major groups, normal transit constipation, slow transit constipation, which is kind of the opposite, and then the potential for overlying both of those is pelvic floor dysfunction, which you just mentioned. And that effects, it's been estimated somewhere between 20 to 30, maybe even slightly more, percentage of patients with chronic constipation symptoms, whether it's chronicidiopathic constipation—what we used to call and still do call functional constipation—or irritable bowel syndrome constipation. And those are disorders of the pelvic floor muscles. And we generally will treat those with biofeedback therapy.

Important to think about, I use the Sutton principle. So 20 to 30% is not 80%. I tend to look for those disorders later if patients don't respond to medical therapy. And I think that nonresponse to medical therapy, laxatives, is a predictor for pelvic floor dysfunction, but you can sometimes get a feeling when you do a digital rectal examination. And you can obviously, and you can also find things such as fissures or, you know, other lesions that would obviate further workup and you need to deal with those things. You know, you find an anal cancer in some patients. If you don't do a digital rectal, you'll never find it. So important to think about doing those. And it can sometimes help direct your therapy to doing some of those diagnostic tests that you might not otherwise do early. Perhaps you do those a little bit earlier based on your findings. But the more you do, the better I think you get at discerning those disorders.

Dr Lembo:  So is constipation constipation? I mean, does it matter if they have IBSC or CIC or FC, whatever you call it these days? I mean, and how would I tell? How would you tell the difference? Is there some simple way you can distinguish them?

Dr Cash: Yeah, so I think that's tough, I think it's a great question, and it's not an easy answer. So, again, when we think about chronic idiopathic constipation, and you can use the synonym functional constipation or even chronic constipation, that implies that patients don't have the primary symptom of abdominal pain associated with their constipation symptoms that we mentioned at the outset. That distinguishes that set of conditions from irritable bowel syndrome with constipation, which is centralized. Is the pain there for that diagnosis? I think it's largely a semantic distinguishing feature. And I often will actually put both diagnoses on for the same patient. There are certain medications that are approved for one versus the other. So, you know, I like to have that latitude to use as many of the therapies that I have available for my patients. But I think the distinguishing features that we've created are helpful for research purposes, but for clinical practice, I think it's largely semantics.

But there are some subtle differences, especially when we get to Megan's area, when we're thinking about treating some of the psychological aspects of these symptoms, especially with the pain predominance in IBS patients, where making those, distinguishing between these two conditions can be very valuable.

Dr Lembo: And I think it's important to highlight the fact that the constipation symptoms are the same. Whether you're chronic idiopathic or IBSC. In fact, some studies suggest that IBSC actually have worse constipation, which is kind of counterintuitive. So really, you can't distinguish them based on bowel symptoms. You have to look at the abdominal symptoms. And there, we're not going to talk too much about pathophys, but there is the hypersensitivity they may have. They're very sensitive. They may have more pain, a lot more abdominal symptoms associated with it so again it's not the bowel it's really the abdominal pain, discomfort, which is as Brooks said usually predominant and it can be quite significant for patients.