IBS in Primary Care: A Practical Approach to Diagnosis and Management

Podcast Transcript

Dr. Brateanu:

Welcome to today’s episode. Today, we are discussing irritable bowel syndrome, or IBS, with Dr. Ari Garber.

Ridhima Kaul:

Let’s start with case 1. We have a 31-year-old female patient presenting to her primary care physician with a 4-month history of diarrhea and abdominal cramping. She usually has 4 non-bloody bowel movements per day with liquid consistency. Her abdominal pain improves with bowel movements. She has no nocturnal symptoms. She started a new job around 6 months ago, has been more stressed than usual, and has lost 2 pounds during that time. She tries to follow a Mediterranean diet. She has only tried Tylenol for abdominal discomfort, which has not helped. She has no relevant past medical or surgical history, no relevant family history, no recent antibiotic use, and does not take any daily medications. Based on this presentation, what would be your differential diagnosis?

Dr. Ari Garber:

The differential diagnosis includes IBS-D, celiac disease, inflammatory bowel disease, infection, exocrine pancreatic insufficiency, dietary intolerance, and small intestinal bacterial overgrowth. Infection is less likely given the chronic time course and lack of nocturnal symptoms, and dietary intolerance is less likely if symptoms are not clearly related to food intake.

IBS is a chronic and often debilitating disorder of gut-brain interaction characterized by recurrent abdominal pain and disordered defecation. Patients with IBS should report abdominal pain at least once weekly, on average, associated with a change in stool frequency, a change in stool form, and/or relief or worsening of pain related to defecation. IBS can be categorized as IBS with diarrhea, IBS with constipation, mixed IBS, or undefined IBS.

Ridhima Kaul:

Having this differential diagnosis in mind, what is the usual workup that you order in this case?

Dr. Ari Garber:

I would start with a limited, targeted workup. This includes baseline laboratory testing to look for anemia or signs of infection, celiac serologies, and fecal calprotectin. If there is recent antibiotic use or infectious exposure risk, such as farm exposure, then additional stool testing may be appropriate.

I also ask about a history of sexual, physical, or verbal abuse, because a significant proportion of patients with new-onset IBS may have a history of trauma or abuse.

Ridhima Kaul:

Can you comment on the cost-effectiveness of different tests? What strategies would you suggest to reach the correct diagnosis while reducing healthcare utilization? When would you proceed with more extensive testing such as colonoscopy or CT enterography?

Dr. Ari Garber:

The 2021 ACG guidelines support a positive diagnostic strategy rather than using IBS purely as a diagnosis of exclusion. In a young, otherwise healthy patient without alarm features, a limited evaluation is usually appropriate.

In the absence of significant anemia, nocturnal symptoms, unintentional weight loss, and with normal celiac serologies and fecal calprotectin, I usually do not pursue endoscopic evaluation. Colonoscopy or cross-sectional imaging would be more appropriate if warning signs are present or if the clinical picture does not fit IBS.

Ridhima Kaul:

Historically, IBS was considered a “diagnosis of exclusion” or “functional” in nature, in contrast to “organic” conditions. Newer guidelines refer to a positive diagnostic strategy instead of a diagnosis of exclusion. More recently, there has also been a shift in perspective and nomenclature toward “disorders of gut-brain interaction.” Can you elaborate on that topic and its practical implications?

Dr. Ari Garber:

The term disorder of gut-brain interaction, or DGBI, is now preferred because it better reflects the biology of these conditions and avoids the stigma associated with the older term “functional.” These disorders are not “less real.” Rather, symptoms can arise from combinations of motility disturbance, visceral hypersensitivity, altered mucosal and immune function, altered gut microbiota, and altered central nervous system processing.

This framework matters clinically because it helps explain why IBS symptoms can be influenced by stress, trauma, diet, gut microbiome changes, and central pain processing. It also explains why neuromodulators can be helpful. We are not using antidepressants because we think the patient is simply depressed; we use them because neurotransmitters in the gut and brain overlap, and these medications can modulate gut pain signaling.

Ridhima Kaul:

Going back to the case, the workup is unremarkable and you diagnose the patient with IBS-D. How would you manage the patient’s symptoms, including pharmacologic and non-pharmacologic interventions?

Dr. Ari Garber:

I usually start with a simple approach. For diarrhea, loperamide can be used, such as 2 tablets in the morning and 1 additional tablet after each diarrheal episode, up to 8 tablets per day. For pain, I would consider a tricyclic antidepressant, again for neuromodulation rather than for depression.

Non-pharmacologic therapy is also important. I would discuss a low-FODMAP diet or Mediterranean-style diet, stress reduction, and education about IBS. If screening for physical, verbal, or sexual abuse is positive, referral for GI psychology or cognitive behavioral therapy can be very helpful.

If symptoms do not improve, I would consider other contributors such as bile acid diarrhea or small intestinal bacterial overgrowth. Breath testing can be considered when SIBO is suspected, and rifaximin may be considered in appropriate patients.

Ridhima Kaul:

Now let’s move to case 2. We have a 42-year-old female patient presenting with constipation. She usually has 1 bowel movement every 3 days, and her abdominal pain improves after passing a bowel movement. She describes her stools as pebble-like. She needs to strain and sometimes needs to squat to pass stool. She also describes a feeling of incomplete evacuation. She has tried over-the-counter Miralax, which helps. She has had 4 vaginal deliveries. She has obesity and has been on a GLP-1 medication for the past year. She has no other relevant past medical or surgical history. For this case, it seems like we are looking at the other side of the spectrum. What would be the suggested workup?

Dr. Ari Garber:

The differential includes IBS-C, medication-induced constipation from the GLP-1 medication, and possible dyssynergic defecation or pelvic floor dysfunction. I would consider basic laboratory evaluation, including thyroid testing and assessment for anemia.

Ridhima Kaul:

Is there any role for testing for pelvic floor dysfunction?

Dr. Ari Garber:

Yes. If the symptoms suggest pelvic floor dysfunction or if constipation is refractory to standard therapy, anorectal manometry can be helpful. If testing is positive, I would refer the patient for pelvic floor physical therapy.

Ridhima Kaul:

We previously talked about treatment of abdominal pain in IBS-D. Are the guidelines for abdominal pain treatment similar in IBS-C? What is your therapeutic approach for the constipation component?

Dr. Ari Garber:

For IBS-C, I usually start with medications that treat constipation and global IBS-C symptoms, such as linaclotide, plecanatide, lubiprostone, prucalopride, or tenapanor, depending on the patient and insurance coverage.

Neuromodulators can also be used for pain. However, because tricyclic antidepressants can worsen constipation, I may choose nortriptyline rather than amitriptyline, or consider other options depending on the patient. I also screen for abuse and pelvic floor dysfunction, and I avoid narcotic analgesics because they worsen constipation.

Ridhima Kaul:

As mentioned earlier, like many of our patients, this patient has been taking a GLP-1 medication. What has been your experience with GI side effects related to GLP-1 therapy, and what is your strategy for dealing with them?

Dr. Ari Garber:

GLP-1 medications can cause gastrointestinal symptoms, including nausea, constipation, and sometimes delayed gastric emptying or gastroparesis-like symptoms. If the symptoms are intolerable, stopping or switching the medication should be considered.

If symptoms are tolerable, we may treat the constipation supportively. However, in general, I prefer not to add multiple medications solely to treat side effects from another medication unless the GLP-1 is providing major medical or quality-of-life benefit.

Ridhima Kaul:

Anecdotally, many patients mention that eliminating certain food groups helps their GI symptoms, whether IBS-C or IBS-D. Is there data to support dietary modification in IBS?

Dr. Ari Garber: 

A low-FODMAP diet can be helpful in both IBS-D and IBS-C. I usually suggest a limited trial for about 4 to 6 weeks. It is important to remember that this diet is restrictive, so the goal is not permanent elimination of all FODMAP foods, but rather reintroduction and personalization based on symptoms.

A Mediterranean-style diet may also be reasonable and easier for some patients to sustain. I generally avoid broad food allergy or food sensitivity testing in IBS unless there are reproducible symptoms with a specific food exposure.

Ridhima Kaul:

What are some future directions in IBS management? Is there a role for probiotics, fecal microbiota transplant, or hypnotherapy?

Dr. Ari Garber:

Fecal microbiota transplant is not standard of care for IBS. Some studies show possible benefit, but the data are not robust enough yet, and this remains an area of ongoing research.

The evidence for probiotics is also limited. There is no clearly preferred formulation and no strong data supporting routine probiotic use for all patients with IBS. That said, if a patient is already taking a probiotic and feels it helps, that is reasonable to acknowledge.

Gut-directed psychotherapy, including cognitive behavioral therapy and hypnotherapy, can be helpful for selected patients, especially as part of a multidisciplinary approach.

Ridhima Kaul:

What is the natural history and prognosis of patients with IBS? What is the role of multidisciplinary care?

Dr. Ari Garber:

IBS does not increase the risk of cancer. Many patients do well with education, frequent follow-up, symptom-directed medications, and attention to psychosocial factors such as trauma or stress.

Multidisciplinary care can be very helpful. This may include GI clinicians, advanced practice providers, GI psychology or psychotherapy, dietitians, and pelvic floor physical therapy when appropriate.

Ridhima Kaul:

For our primary care audience, when is a good time to refer a patient with IBS symptoms to GI?

Dr. Ari Garber:

Many patients can be managed in the primary care or internal medicine clinic, but IBS often requires a multidisciplinary effort. Referral to GI is appropriate for refractory symptoms, anemia, unintentional weight loss, nocturnal symptoms, or other features that do not fit Rome IV criteria or suggest an alternative diagnosis.

Dr. Brateanu:

Thank you, Dr. Ari Garber, and thank you to our listeners for joining us for this discussion on irritable bowel syndrome.