Diagnosis of IBS
 

Dr Schiller, why don't we start with you? Traditionally, it's been difficult to accurately identify and diagnose patients with IBS. Is there a standard approach that you take in the initial history and physical? If so, what are the key questions that you would ask in taking a history?

Lawrence Schiller MD: I think the key points are to be sure that the person has abdominal pain that's related in some way to the abnormal defecation pattern that they're having. If someone has just abdominal pain that's unrelated to a change in defecation, then they don't have irritable bowel syndrome.

Peter Salgo MD: What about dietary intake? Is that part of your standard history?

Lawrence Schiller MD: I think it's very important to get an idea about people's dietary intake. And the main reason for that is that it illuminates some of the factors that may be causing or accelerating their symptoms.

Peter Salgo MD: But again, you're making this diagnosis on history, aren't you?

Lawrence Schiller MD: Absolutely.

Peter Salgo MD: So, when Dr Sweeting - who actually taught me all of the GI medicine I knew in medical school - told me that if I didn't have the diagnosis by the end of taking the history, I would never have it, he was right.

Lawrence Schiller MD: Absolutely, for IBS.

Peter Salgo MD: These symptoms - it seems to me - are not only annoying and possibly even debilitating, but they tend to be embarrassing. So, Lin, how do you approach this doctor-patient relationship issue? Patients are, I suspect, reluctant to even talk about this, aren't they?

Lin Chang MD: I think patients are reluctant. Typically, I will spend a fair amount of time with them when I first meet them. And that's just to get a good history, build a good relationship with the patient, have them form a trusting relationship so that they will tell you about their symptoms and be more specific. So you can really figure out the impact of their symptoms on the quality of life, see how they cope with their symptoms, what type of treatments they've been on. I think that's really important to having a successful outcome.

Peter Salgo MD: Trust. That's a word I haven't heard for a while. That takes time, doesn't it? How do you do that in today's environment?

Lin Chang MD: I think one thing is spending time with them, which is difficult in the present health care situation. But listening to them, doing something called active listening, where they're doing more of the talking than you, validating their symptoms, giving them hope - I think those are important.

Peter Salgo MD: Joe, are there specific risk factors that you need to go looking for when you're trying to establish this diagnosis and investigating it?

Joseph Sweeting MD: Yes, there are a number of risk factors that really have to be addressed. A family history of possible colon cancer is one important point. And we need to know whether the patient has had an episode of recent infectious disease: that's important, particularly if it involved diarrhea or the GI tract.

We also need to find out something about the early experience of the patient. It turns out that patients with irritable bowel syndrome seem to have a higher incidence of physical and, often, sexual abuse in childhood; so that's an important factor.

And then of course we want to get some of the history about possible alarm symptoms, such as rectal bleeding. We want to be aware of pain that doesn't follow the pattern of irritable bowel, in other words pain that's not associated with defecation, or pain or diarrhea that occur in the middle of the night. These are all factors that are atypical for the irritable bowel syndrome, and the more you hear of these atypical findings, the less sure you are about the diagnosis of irritable bowel.

Peter Salgo MD: Two other risk factors, though, that bring us back to irritable bowel; the two I always hear about, are female gender and antibiotic use. Those two seem to always come up.

Peter Salgo MD

Lawrence Schiller MD

Joseph Sweeting MD: Well, the female gender is such an obvious thing. One doesn't have to take a history for that, really, does one? But it's true that two-thirds of the patients with this problem are female, at least in this country.

Antibiotic use can cause diarrhea, but it's not ongoing, it doesn't go on for months and years the way the pattern does with irritable bowel. So we ask about it, it's important, but it doesn't really help us to come to the diagnosis of an irritable bowel syndrome.

Peter Salgo MD: Now, Larry, I know you like the history. You really depend on the history, but I'm going to pin you down on a little lab work here. So let's start first for a patient with constipation. What are the lab results that you're looking for? What are you going to do?

Lawrence Schiller MD: I think that one of the key things you want to do in all patients is to check a blood count, because anemia certainly is one of the alarm symptoms that we worry about and which would require further workup. You also want to make sure you do a stool guaiac for the same reason, particularly in the constipated patients to be sure that they don't have a problem with a tumor in their large bowel that may be causing their difficulties. That, of course, is much more likely in the older patients, and requires us to take a look inside - at least at the sigmoid and perhaps the entire colon, in order to understand that they don't have a problem with neoplasia.

Peter Salgo MD: Let's go over the alarm symptoms at least once more, because I think that's something we don't want any clinician to miss.

Lawrence Schiller MD: I think that's absolutely correct. The main things that you want to look out for are rectal bleeding, and be sure that the person doesn't have a problem with weight loss. You also want to be sure that they don't have difficulty with eating. If they have problems with any of those activities, one really needs to look out for other diagnoses.

Peter Salgo MD: This would ratchet up your concern a great deal?

Lawrence Schiller MD: Absolutely.

Peter Salgo MD: Let's go on to the patient with diarrhea now. How would you approach the laboratory workup on that patient?

Lawrence Schiller MD: In diarrhea, we worry about a host of other problems that can cause chronic diarrhea. There are probably over 400 different things that can do that and so we need to be concerned about many larger possibilities. However, the pattern in irritable bowel is very characteristic and the diarrhea is rarely continuous. And, as has been mentioned, it's associated with pain. Pain's the main symptom in irritable bowel syndrome and if someone has painless diarrhea, we no longer characterize that person as having irritable bowel; we have to look at other possibilities to explain that.

Peter Salgo MD: Lin, I'm listening to this and, as a non-gastroenterologist, the one phrase I haven't heard is 'invasive procedure'. Don't you guys come to the office with a scope in your briefcase and just whip it out for every patient?

Who needs to be endoscoped? What's going on here?

Lin Chang MD: Anyone 50 years of age or older really requires a colon examination in the form of colonoscopy or a flexible sigmoidoscopy and barium enema. In patients under the age of 50, with typical symptoms of IBS without any of those alarm symptoms, you really don't have to do invasive procedures.

Peter Salgo MD: So, really, we've moved away from everybody gets scoped all the time?

Lin Chang MD: Yes, definitely. The ACG (American College of Gastroenterologists) and AGA (American Gastroenterlogical Association) have come out with guidelines for diagnosis of IBS, and this is stated by both groups.

Peter Salgo MD: Larry, are there standard diagnostic criteria out there for making the diagnosis of irritable bowel?

Lawrence Schiller MD: Yes, Peter, over the years several have been promulgated. About 15 years ago, the Manning criteria were developed, prospectively tested and shown to be able to differentiate people with functional bowel problems from those with organic problems that needed further attention. And since that time, there have been several expert committees that have gotten together.

The one with the longest track record is the Rome committee. In that process, experts in the field got together and promulgated criteria that they felt would be good for the diagnosis of the irritable bowel syndrome.

Peter Salgo MD: Okay. And then we have the ACG Task Force, right?

Lawrence Schiller MD: Right. Lately, that's in some ways a more general or practical sort of criteria for the diagnosis of IBS.

Peter Salgo MD: Is it fair to say that Manning is old, that we've gone beyond Manning at this point?

Lawrence Schiller MD: I'm not so sure that's really true, because the Rome I criteria have been tested now and found to be fairly good. The Rome II criteria are in the process of being validated. And the ACG one has not been subjected to any sort of scientific testing. So if you look back on it, the Manning criteria still hold up pretty well.

Peter Salgo MD: I keep hearing, Rome I, Rome II, they're great for those researchers out there but the ACG Task Force work has the clinical criteria we need. Is that a fair distinction?

Lawrence Schiller MD: Well, I don't know that I'd make it that boldly. I think the Rome criteria can be useful to clinicians in practice, in the sense that patients meeting those criteria will be like patients who are in studies. And you could expect that their response to different medicines would be similar to those of the people who were in those studies.

Joseph Sweeting MD: It's also interesting to note that there really isn't that much difference between Manning, Rome I, Rome II. At least, those three - they're all talking about the same thing. They put them in different order and they try to subdivide them a little bit differently, but the basic concepts are the same.

Peter Salgo MD: Why don't you run that down for us? What is Rome II?

Joseph Sweeting MD: Rome II is a useful tool that I think all of us use to some extent, even though it was set up primarily for research purposes. It goes something like this. A patient probably does have an irritable bowel syndrome if they, for the past year, at least 12 weeks, they've had the following symptoms: abdominal pain that is relieved by defecation, or the onset of the pain occuring with a change in either the frequency or the characteristic of the bowel movement. If you have two out of those three criteria, then you - by the Rome criteria - do have an irritable bowel syndrome.

There are some additional findings, or aspects, that can be helpful, and the more of those that you have, the surer you can be. They go something along the following lines: if a patient has rather abnormal bowel habits, such as more than three bowel movements in a day or less than three bowel movements in a week, if he or she tend to have very abnormal type of stools or mucous in the stool, if he or she have abdominal bloating, these findings add to one's certainty about the diagnosis.

Peter Salgo MD: How accurate are the Rome criteria?

Joseph Sweeting MD: It's not only the Rome criteria, but using them along with some of the other things that have been mentioned actually can be quite reassuring. There are some very nice studies that show that if one really makes a firm diagnosis of the irritable bowel syndrome and then looks at that group of patients, say, five years later, the incidence of a different diagnosis emerging is in the range of 3 to 5%. The overwhelming majority of the patients retain the same diagnosis, which is a long-winded way of saying you made the correct diagnosis in the first place.

I think all of us here would agree that history is the key to this, but one does have to examine the patient also.

Joseph Sweeting MD: You have to do a little bit more than that, yes. You have to lay your hand on the patient at some point.

Joseph Sweeting MD: You have to take the time to listen, and but also to examine and to do the appropriate studies. What we're really saying is that if you do these things - and they're not very elaborate - you come up with figures that give you this very high assurance rate that you've made the correct diagnosis.

Peter Salgo MD: Well, I know the three of you are convinced, but is everybody else convinced? Is it universally accepted, for example, that the Rome II criteria are the gold standard by other gastroenterologists?

Lin Chang MD: Rome II - as opposed to Rome I - has actually been simplified to make it easier for physicians to use. But in general, the Rome criteria are used more to standardize the diagnosis, particularly for research purposes. I think they are definitely accepted by gastroenterologists as criteria that you would use to diagnose IBS. The question would be whether or not physicians are using them in their practices on a day-to-day basis.

Peter Salgo MD: Are they?

Lin Chang MD: I'm not sure that they are. I think some are, I think others are just diagnosing IBS if they see chronic pain or recurrent pain or discomfort associated with disturbed bowel function and are not necessarily asking, "Do you have 12 weeks in the past 12 months associated with these several other features?"

Peter Salgo MD: How does the ACG Task Force classify these patients?

Lawrence Schiller MD: I think they're the same categories that we see in all the others. That is, irritable bowel syndrome with constipation, irritable bowel with diarrhea and irritable bowel with alternating bowel habits.

Peter Salgo MD: Is this, to the uninitiated doctor, a distinction without a difference or is it really important to try to parse this out this way, Joe?

Joseph Sweeting MD: I think that's a useful way to approach it, because the diagnostic approach and, obviously, the therapy are going to vary quite a bit, depending on whether you're dealing with a patient with constipation or diarrhea or someone who's going back and forth between the two. People do move from one group to the other in a way that I don't think anybody has ever really explained very well. But we see patients who have diarrhea for years and then they wind up with constipation and vice-versa.

The people with diarrhea often need quick evaluation and treatment to try to control that. Some of the patients have incontinence, which adds greatly to their discomfort, and one has to approach the treatment of that very quickly. Constipation can be approached with slower trials. But these distinctions, these differences really lead us in the direction of management.

The diagnosis still depends, I think, largely on the history that we get from the patient and the essential physical and laboratory data that we acquire.

Peter Salgo MD: When you're doing this, of course, what you need to establish is a differential. Not everything that looks like and sounds like IBS is IBS. So what are the parts of the differential diagnosis, Joe?

Joseph Sweeting MD: Well, the age factor becomes paramount there. In the younger patient - let's say under 40 - where the patient has pain and some diarrhea, there are a number of other diseases that have to be considered. Celiac disease is one and I think we've learned that there is more celiac disease in the environment than we used to think. Screening for that in that group of patients, screening with blood tests, antibody markers and so forth, is probably appropriate. But it's not really appropriate in the older patient, particularly.

In the older patient, rather, we have to rule out things like neoplasia. We look for tumors in the bowel, particularly in the large bowel. We look for inflammatory bowel disease, which, of course, can occur both in the younger and the older group.

In people with chronic diarrhea, the infectious type of diarrhea, if it's really been going on for a long period of time, we don't think so much in terms of a bacterial infection, since that doesn't really persist, but more in terms of parasites. I happen to work in New York City, where we see quite a few patients from the Caribbean area, and we have a rather surprisingly high yield of things like Strongyloides and certainly Giardia.

The other form of the irritable bowel syndrome presents with constipation. Here the differential is quite different. In the older patient, of course, the main differential is with mechanical obstruction, either from a mass, or from some pre-existing stricture. This requires a thorough evaluation of the GI tract. In the younger patient, the differential involves such things as excessive laxative use, excessive weight loss, often from an anorexia syndrome in the early years, which frequently manifests as constipation later in life. And pelvic floor dysfunction in the multiparous patient.

Peter Salgo MD: I don't want to leave this segment without touching on the alarm symptoms once more, because that's really critically important here. You don't want to carry somebody with irritable bowel who really has something far more dire. So, Lin, for the last time, could you run down why we call these alarm symptoms and what they are and just lay out what we're looking for? We're talking about neoplasia here; we're talking about cancer, right?

Lin Chang MD: It's not only cancer, but the alarm symptoms are important to know, because they may signify organic disease and not functional bowel disease, such as irritable bowel syndrome. They include blood in the stool, significant weight loss, for example, ten pounds of weight; refractory diarrhea, anemia, recurring fever. Those will all be symptoms suggesting the patient may have an organic illness, such as colon cancer or inflammatory bowel disease.