Ep 167: A 23-Year-Old with Abdominal Pain and Diarrhea

This episode reviews the differential diagnosis of abdominal pain in a young woman, along with the classification and treatment of the underlying condition.

Read more on this topic in Harrison.

Harrison's Principles of Internal Medicine, 22nd Edition

Transcript

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[Ms. Heidhausen] This is Katarina Heidhausen, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. 

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[Dr. Handy] Hi, everyone. Welcome back to Harrison's Podclass. We're your co-hosts. I'm Dr. Cathy Handy. 

[Dr. Wiener] And I'm Dr. Charlie Weiner, and we're joining you from the Johns Hopkins School of Medicine. Welcome to Harrison's Podclass. Today's patient is a 23-year-old with abdominal pain and diarrhea. Cathy, today we're seeing a 23-year-old woman who comes to see you for four to five years of abdominal pain and diarrhea that has now worsened since she took a job out of college as a financial analyst. 

[Dr. Handy] Am I the first physician she's seeing about this? 

[Dr. Wiener] No, these symptoms started in college, and she was seen at Student Health. They tested her stool and told her that she did not have an infection. Now that she has a job, she has insurance, and she really wants to solve the problem. Also, she's noted that since starting work, her pain and diarrhea have worsened, sometimes interfering with her work. 

[Dr. Handy] Tell me more about the pain and its precipitants. 

[Dr. Wiener] She reports that on many days she has a dull ache, mostly in her lower abdomen, and then one or two times a week it worsens over the day. The pain may be sharp or dull and typically occurs on her right side, but not always. She gets some relief from a bowel movement, and she does notice that it worsens before and during her menses. Antacids and proton pump inhibitors have not helped. She also tried a gluten-free diet and eliminating dairy products, but neither of those helped either. 

[Dr. Handy] You also mentioned diarrhea. Tell me about that. 

[Dr. Wiener] Yeah, she typically has two to three bowel movements per day that are small and have some mucus. When the pain is bad, she'll have urgency such that if she does not get to the bathroom quickly enough, she'll have some bowel incontinence. She often wears a pad to protect herself at work. 

[Dr. Handy] Any systemic symptoms like fevers and weight loss? And do any of the symptoms that she's describing so far happen at night? 

[Dr. Wiener] She's never had fevers with the abdominal pain, and her weight has been stable for the last four years. Also, she does say that she looks forward to going to sleep after a tough day 'cause the pain and the diarrhea don't wake her. She sleeps well. 

[Dr. Handy] Medications, habits, any family history of cancer? 

[Dr. Wiener] She does not take any medication and currently has no sexual partners. She does not drink alcohol, smoke, or use any illicit drugs. No one in her family has or has had cancer. Her parents and her grandparents are alive and well. She has a brother who's in college, and he's healthy. 

[Dr. Handy] You mentioned stool cultures. Has she had any other tests for this problem? 

[Dr. Wiener] Yes, while in college, she had a right upper quadrant ultrasound that was normal, it did not show any gallstones. 

[Dr. Handy] How about her physical examination? 

[Dr. Wiener] She's well-developed and appears well-nourished. She's 5' 9", weighs 135 lbs, which calculates to a BMI of 20. Her vitals, her cardiac exam, her lungs, all of those are normal. Her abdominal exam is very unremarkable. She reports mild left mid-quadrant pain, but her abdomen is generally soft with good bowel tones. There's no rebound, there's no organomegaly. Her skin, joints, and neurologic exam are also normal. 

[Dr. Handy] Okay, let me just say that I think we have enough information to say that this woman has irritable bowel syndrome. 

[Dr. Wiener] Really? Tell me more. 

[Dr. Handy] Irritable bowel syndrome, or IBS, is a chronic functional bowel disorder characterized by abdominal pain or discomfort and altered bowel habits, and the absence of detectable structural abnormalities. No clear diagnostic markers exist. So the diagnosis of the disorder is based on clinical presentation. It's incredibly common, with up to 10% of adults and adolescents having symptoms consistent with irritable bowel syndrome. 

[Dr. Wiener] If there are no markers, how do you diagnose it? 

[Dr. Handy] It's a clinical diagnosis. The Rome IV diagnostic criteria for irritable bowel syndrome require recurrent abdominal pain, on average at least one day per week in the last three months. And it has to be associated with at least two of the following criteria. So abdominal pain that's related to defecation associated with the change and frequency of stool, associated with a change in form or appearance of stool. And these symptoms have to have been going on for over six months. Painless diarrhea or constipation no longer fulfill the diagnostic criteria to be classified as IBS. Supportive symptoms that are not part of the diagnostic criteria include straining, urgency or a feeling of incomplete defecation, passing mucus, or bloating. 

[Dr. Wiener] So altered bowel habits are the hallmark. Our patient has diarrhea. What about constipation? 

[Dr. Handy] IBS can be classified into IBS with predominant constipation or IBS with predominant diarrhea, and IBS with both mixed constipation and diarrhea. However, bowel pattern subtypes are highly unstable. Many patients change subtypes over time and it's not constant. Patients with IBS, the constipation type, have symptoms of hard stools often with narrow caliber, less than three bowel movements per week, incomplete evacuation, straining, a sensation of anal blockage, and digitalization. On the other hand, those with IBS diarrhea usually have small volumes of loose stools. This is often associated with fecal urgency, the passage of mucus and in some cases incontinence. Diarrhea may be aggravated by emotional stress or eating. 

[Dr. Wiener] Sounds exactly like our patient. 

[Dr. Handy] Yes, and importantly, weight loss, nocturnal symptoms, and bleeding per rectum are not common in patients with IBS. And if those are present, it should warrant evaluation for other causes of the symptoms. 

[Dr. Wiener] Do we understand the underlying mechanism or mechanisms for IBS? 

[Dr. Handy] That will be a no. The pathogenesis of IBS is poorly understood, although roles of abnormal gut, motor, and sensory activity, central neural dysfunction, psychological disturbances, mucosal inflammation, stress, luminal factors such as bile acid, malabsorption, gut dysbiosis, those are all things that have been proposed. 

[Dr. Wiener] The differential has to be huge. Don't you have to rule out lots of things before you come to the diagnosis? 

[Dr. Handy] Yeah, and that's why this can be a burden to the patient and to the healthcare system; but this patient highlights why the approach has to be careful and individualized. 

[Dr. Wiener] What are some factors that would suggest a different diagnosis? 

[Dr. Handy] The appearance of the disorder for the first time in old age, progressive course from time of onset, rectal bleeding, significant weight loss, persistent diarrhea even after a 48-hour fast, and presence of nocturnal diarrhea or steatorrheal stools argue against the diagnosis of IBS. When diarrhea is the major complaint, the possibility of lactase deficiency, laxative abuse, malabsorption, celiac sprue, hyperthyroidism, inflammatory bowel disease, and infectious diarrhea. All of those have to be ruled out. 

[Dr. Wiener] And I'm also sure you have to consider peptic ulcer disease, biliary disease, malignancies, all the other GI disorders, right? 

[Dr. Handy] Absolutely, but that's why this woman's history over many years was so helpful. Few tests are required for patients who have typical IBS symptoms and no alarm features. Unnecessary investigations may be costly and even harmful. The AGA has delineated factors to be considered when determining the aggressiveness of the diagnostic evaluation. These include the duration of symptoms, the change in symptoms over time, the age and sex of the patient, the referral status of the patient, prior diagnostic studies, a family history of colorectal malignancy, and the degree of psychosocial dysfunction. 

[Dr. Wiener] So that's why it's important that in our patient, she's had symptoms for about four years, and on presentation, her weight seemed normal. And she also told you no nocturnal symptoms, that really helped you, didn't it? 

[Dr. Handy] Yeah, a lot of the red flag symptoms that we talked about are not present here. And she also has had significant workup already. By the way, are you going to ask me a question? 

[Dr. Wiener chuckles] Yes. So let's accept that she has IBS. And the question's going to ask, in this patient, all of the following may provide symptomatic relief, except? A. antispasmodics; B. eluxadoline; C. a high FODMAP diet, FODMAP being fermentable oligosaccharides, disaccharides, monosaccharides, and polyols; D. stress management; or E. stool bulking agents. 

[Dr. Handy] I'm going to take them out of order. First, reassurance and careful explanation of what we understand now as a functional nature of the disorder are of primary importance, along with counseling on how to identify triggers for the patient's IBS symptoms. Stress management may be helpful if stress is a trigger. 

[Dr. Wiener] Sounds like it is in her case. What's next? 

[Dr. Handy] Stool bulking agents such as high-fiber diets and fiber supplementation are frequently used in treating IBS. Fiber supplementation with cilium has been shown to reduce perception of rectal distension. That indicates that fiber may have a positive effect on visceral afferent function. I'll also add that IBS constipated patients often improve with osmotic laxatives. 

[Dr. Wiener] Our patient has more diarrheal symptoms. How about the antispasmodics or the antidiarrheals? 

[Dr. Handy] Also true. Peripherally acting opioid-based agents such as loperamide are the initial choice of therapy for IBS diarrhea. Physiologic studies demonstrate increases in segmenting colonic contractions, delays in fecal transit, increases in anal pressures, and reductions in rectal perception with these drugs. Anticholinergic drugs may provide temporary relief for symptoms such as painful cramps related to intestinal spasm. Although controlled clinical trials have produced mixed results, evidence generally supports the beneficial effects of anticholinergic drugs for pain. 

[Dr. Wiener] What about eluxadoline? 

[Dr. Handy] It's a locally acting mixed opioid receptor agonist and antagonist with minimal systemic bioavailability. So it's an antidiarrheal. Eluxadoline is FDA-approved for treating abdominal pain and diarrhea in patients with IBS-D. Just take note that given a small risk of pancreatitis with the drug, it should not be prescribed for patients with prior cholecystectomy or significant alcohol use or prior history of pancreatitis. 

[Dr. Wiener] Okay, that leaves the FODMAP diet. 

[Dr. Handy] Yes, a high FODMAP diet is bad and a low FODMAP diet may be beneficial for these patients, but that means cutting out lots of tasty foods. FODMAPs include things like fructose-rich fruits such as apples, cherries, mangoes, and watermelon; a bunch of vegetables like asparagus, Brussels sprouts, cauliflower, mushrooms, pistachios. So again, an individualized approach is best. 

[Dr. Wiener] Okay, before we close, I have to ask you about probiotics 'cause somebody's going to ask about them. 

[Dr. Handy] Multiple meta-analyses have suggested that probiotics might be an effective strategy in improving global IBS symptoms, including abdominal pain and bloating; but these studies have been limited by relatively small sample sizes and short durations. Because of this, it's unclear which probiotics to recommend for patients with IBS. The American Gastroenterological Association makes no recommendations for use of probiotics in patients with IBS. I'll also add that antibiotic treatment, such as rifaximin, benefits a subset of IBS patients. In two identical double-blind placebo-controlled trials of non-constipated IBS, rifaximin showed symptom improvement and it's approved by the FDA for treatment of IBS-D. 

[Dr. Wiener] So may be useful in our patient. 

[Dr. Handy] Exactly. 

[Dr. Wiener] So the teaching points in this case are that IBS is a clinical diagnosis that relies on a very comprehensive history and the absence of warning signs. Broadly, there are two phenotypes, predominantly diarrheal or constipation, but there's lots of overlap. The mechanism is not fully understood, but there are a variety of psychological, dietary, and pharmacological approaches that may benefit the patients, but these require an individualized and systemic approach. 

[Dr. Handy] You can find this question and other questions like it in Harrison's Self-Review book. And you can read more about this topic in the Harrison's chapter on irritable bowel syndrome. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on AccessMedicine. If you enjoyed this episode, please leave us a review, so we can reach more listeners just like you. Thanks so much for listening. 

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