Guideline sources The following summarized guidelines for the evaluation and management of irritable bowel syndrome are prepared by our editorial team based on guidelines from the United European Gastroenterology (UEG/ESPEN 2023), the American Gastroenterological Association (AGA 2022; 2020; 2012), the American College of Gastroenterology (ACG 2021), the British Society of Gastroenterology (BSG 2021), and the Canadian Association of Gastroenterologists (CAG 2019). 1 2 3 4 5 6 7 8 9 10 10 11 12 12 13 Definition IBS is a functional gastrointestinal disorder characterized by recurrent abdominal pain and altered bowel habits (constipation, diarrhea or both), often with associated bloating. 10 Epidemiology https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 1/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway The etiology of IBS is poorly understood. Potential etiological mechanisms include genetic factors (most notably an identified mutation of SCN5A); post-infectious changes, chronic infections and disturbances in the intestinal microbiota; low-grade mucosal inflammation, immune activation, and altered intestinal permeability; disordered bile salt metabolism (in 10-20% of patients with diarrhea); abnormalities in serotonin metabolism; and alterations in brain function. 10 Pathophysiology In the United States, the incidence of IBS is estimated at 196 cases per 100,000 person-years, with an estimated prevalence of 5-12% based on Rome II criteria. 11 Disease course Key clinical manifestations include abdominal pain or discomfort, bloating, diarrhea, and constipation. 12 Prognosis and risk of recurrence There is no evidence that IBS is associated with an increased risk of mortality. However, patients with IBS exhibit a poorer quality of life and utilize the healthcare system to a greater degree than patients without the diagnosis. 12 13 Guidelines 1. Screening and diagnosis Diagnosis: As per ACG 2021 guidelines: Adopt a positive diagnostic strategy over diagnostic strategy of exclusion to improve cost- effectiveness in patients with symptoms of IBS. A Consider adopting a positive diagnostic strategy over diagnostic strategy of exclusion to improve time to initiate appropriate therapy in patients with symptoms of IBS. E As per BSG 2021 guidelines: Consider using the NICE definition of IBS (abdominal pain or discomfort, in association with altered bowel habit, for at least 6 months, in the absence of alarm symptoms or signs) in primary care than diagnostic criteria derived from patients in secondary care, such as the Rome IV criteria. C Make a positive diagnosis of IBS based on symptoms, in the absence of alarm symptoms or signs, and abnormalities on simple blood and stool tests. B 2. Classification and risk stratification Classification: https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 2/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway Consider categorizing patients based on an accurate IBS subtype to improve patient therapy: Situation Guidance > 25% of bowel movements with Bristol stool scale types 1-2 and < 25% with types 6-7 IBS-C > 25% of bowel movements with Bristol stool scale types 6-7 and < 25% with types 1-2 IBS-D > 25% of bowel movements with Bristol stool scale types 1-2 and > 25% with types 6-7 IBS-M Meets diagnostic criteria for IBS but bowel habits not accurately categorized in any of the subtypes. E IBS-U Recognize that Bristol stool scale categorizes stool appearance into the following types: Situation Guidance Separate hard lumps, like nuts (hard to pass) Type 1 Sausage-shaped but lumpy Type 2 Like a sausage but with cracks on its surface Type 3 Like a sausage or snake, smooth and soft Type 4 Soft blobs with clear cut edges (passed easily) Type 5 Fluffy pieces with ragged edges, a mushy stool Type 6 Watery, no solid pieces (entirely liquid). Type 7 3. Diagnostic investigations Laboratory tests: As per ACG 2021 guidelines, consider obtaining CRP to rule out IBD in patients with suspected IBS and diarrhea symptoms without alarm features. B Show 3 more https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 3/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway As per BSG 2021 guidelines: Obtain the following laboratory tests in all patients presenting with symptoms of IBS for the first time in primary care: CBC CRP or ESR celiac serology fecal calprotectin (in patients < 45 years of age with diarrhea) to exclude IBD. B Follow local and national guidelines for colorectal and ovarian cancer screening, where indicated. B As per CAG 2019 guidelines, do not obtain CRP in patients with IBS to exclude inflammatory disorders. D Show 2 more Food allergy testing: As per ACG 2021 guidelines, do not obtain testing for food allergies and food sensitivities in all patients with IBS unless there are reproducible symptoms concerning food allergy. D As per CAG 2019 guidelines, do not obtain food allergy testing to identify triggers of IBS symptoms in patients with IBS. D Breath testing: As per BSG 2021 guidelines, do not obtain hydrogen breath testing to rule out SIBO or carbohydrate intolerance in patients with typical IBS symptoms. D As per CAG 2019 guidelines, do not obtain routine lactose or glucose hydrogen breath testing in the evaluation of patients with IBS. D Diagnostic imaging: avoid obtaining repeated CT in patients with functional abdominal pain unless there is a major change in clinical findings or symptoms. D Evaluation for bile acid diarrhea: consider obtaining SeHCAT scanning or serum 7alpha- hydroxy-4-cholesten-3-one to exclude bile acid diarrhea in patients with symptoms suggestive of IBS-D, but with atypical features such as nocturnal diarrhea, or a prior cholecystectomy. B Evaluation for pancreatic insufficiency: do not obtain evaluation for exocrine pancreatic insufficiency in patients with typical IBS symptoms. D 4. Diagnostic procedures Colonoscopy: As per ACG 2021 guidelines, do not perform routine colonoscopy in < 45 years old patients with symptoms of IBS without warning signs. D As per BSG 2021 guidelines, do not perform colonoscopy in patients with IBS unless in the presence of alarm symptoms or signs, or symptoms suggestive of IBS-D with atypical features and/or relevant risk factors increasing the likelihood of microscopic colitis (female gender, age https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 4/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway 50 years, coexistent autoimmune disease, nocturnal or severe, watery diarrhea, duration of diarrhea < 12 months, weight loss or use of potential precipitating drugs including NSAIDs, PPIs). D As per CAG 2019 guidelines, do not perform routine colonoscopy in < 50 years old patients with IBS without alarm features to exclude alternative diagnoses. D Show 2 more Anorectal physiology testing: As per ACG 2021 guidelines, consider performing anorectal physiology testing in patients with IBS and symptoms suggestive of a pelvic floor disorder and/or refractory constipation not responsive to standard medical therapy. E As per BSG 2021 guidelines, consider obtaining anorectal physiology tests, where available, in patients with IBS and coexisting symptoms suggestive of a defecatory disorder or fecal incontinence, to select patients potentially to benefit from biofeedback. C 5. Medical management Antispasmodics: As per AGA 2022 guidelines, consider offering antispasmodics in patients with IBS. C As per ACG 2021 guidelines, do not use antispasmodics to improve global symptoms in patients with IBS. D As per BSG 2021 guidelines, consider offering certain antispasmodics for global symptoms and abdominal pain in patients with IBS. Recognize that dry mouth, visual disturbance and dizziness are common side effects. C As per CAG 2019 guidelines, consider offering certain antispasmodics (such as dicyclomine, hyoscine, pinaverium) to improve symptoms in patients with IBS. C Antidepressants, TCAs: As per AGA 2022 guidelines, consider offering TCAs in patients with IBS. C As per ACG 2021 guidelines, offer TCAs to improve global symptoms in patients with IBS. B As per BSG 2021 guidelines, offer TCAs (at a low dose, such as 10 mg amitriptyline once daily, and titrated slowly to a maximum of 30-50 mg once daily) as second-line therapy, initiated in primary or secondary care, for global symptoms and abdominal pain in patients with IBS. Provide patients with a careful explanation to the rationale for their use and counsel about their side effect profile. B As per CAG 2019 guidelines, offer low-dose TCAs to improve symptoms in patients with IBS. A Antidepressants, SSRIs: As per AGA 2022 guidelines, consider offering SSRIs in patients with IBS. C As per BSG 2021 guidelines, consider offering SSRIs as second-line therapy, initiated in primary or secondary care, for global symptoms in patients with IBS. Provide patients with a careful explanation to the rationale for their use and counsel about their side effect profile. C https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 5/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway As per CAG 2019 guidelines, consider offering SSRIs to improve symptoms in patients with IBS. C Probiotics: As per ACG 2021 guidelines, consider avoiding the use of probiotics to improve global symptoms in patients with IBS. D As per BSG 2021 guidelines, consider offering probiotics for up to 12 weeks for global symptoms and abdominal pain in patients with IBS. Discontinue if there is no improvement in symptoms after 12 weeks. Insufficient evidence to recommend a specific species or strain of probiotics. C As per AGA 2020 guidelines, insufficient evidence to support the use of probiotics in symptomatic adult and pediatric patients with IBS. Use probiotics only in the context of a clinical trial. I As per CAG 2019 guidelines, consider offering probiotics to improve symptoms in patients with IBS. C Management of diarrhea, eluxadoline: As per AGA 2022 guidelines, consider offering eluxadoline in patients with IBS-D. C As per ACG 2021 guidelines, consider offering mixed opioid agonists/antagonists (eluxadoline) to improve global symptoms in patients with IBS-D. C As per BSG 2021 guidelines: Offer eluxadoline, a mixed opioid receptor drug, as second-line therapy in patients with IBS-D in secondary care. B Do not use eluxadoline in patients with a history of sphincter of Oddi problems or cholecystectomy, alcohol dependence, pancreatitis, or severe liver impairment. D As per CAG 2019 guidelines, consider offering eluxadoline to improve symptoms in patients with IBS-D. C Management of diarrhea, rifaximin: As per AGA 2022 guidelines: Consider offering rifaximin in patients with IBS-D. C Consider re-offering rifaximin in patients with IBS-D with an initial response to rifaximin developing recurrent symptoms. C As per ACG 2021 guidelines, offer rifaximin to improve global symptoms in patients with IBS-D. B As per BSG 2021 guidelines, offer rifaximin, a non-absorbable antibiotic, as second-line therapy in patients with IBS-D in secondary care. B Management of diarrhea, 5-HT3 antagonists: As per AGA 2022 guidelines, consider offering alosetron in patients with IBS-D. C As per ACG 2021 guidelines, offer alosetron in female patients with severe IBS-D failed conventional therapy. B https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 6/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway As per BSG 2021 guidelines, offer 5-HT receptor antagonists as second-line therapy in patients with IBS-D in secondary care. Recognize that alosetron and ramosetron are unavailable in many countries; consider using ondansetron titrated from a dose of 4 mg once daily to a maximum of 8 mg TID as a reasonable alternative. Recognize that constipation is the most common side effect. B Management of diarrhea, loperamide: As per AGA 2022 guidelines, consider offering loperamide in patients with IBS-D. C As per BSG 2021 guidelines, consider offering loperamide as first-line therapy for diarrhea in patients with IBS. Recognize that abdominal pain, bloating, nausea and constipation are common, and may limit tolerability. Titrate the dose carefully to avoid this. B As per CAG 2019 guidelines, consider avoiding the use of continuous loperamide to improve symptoms in patients with IBS-D. D Management of diarrhea, bile acid sequestrants: As per ACG 2021 guidelines, consider avoiding the use of bile acid sequestrants to improve global symptoms in patients with IBS-D. D As per CAG 2019 guidelines, consider avoiding the use of cholestyramine to improve symptoms in patients with IBS-D. D Management of constipation: As per PEG 2022 guidelines, consider offering polyethylene glycol laxatives in patients with IBS- C. C As per PEG 2021 guidelines, consider avoiding the use of polyethylene glycol products to improve global symptoms in patients with IBS-C. D As per PEG 2021 guidelines, consider offering polyethylene glycol for constipation in patients with IBS. Recognize that abdominal pain is a common side effect. C As per PEG 2019 guidelines, consider avoiding the use of osmotic laxatives (polyethylene glycol) to improve overall symptoms in patients with IBS-C. D Management of constipation, 5-HT4 agonists: As per AGA 2022 guidelines, consider offering tegaserod in patients with IBS-C. C As per ACG 2021 guidelines, consider offering tegaserod in < 65 years old female patients with IBS-C and 1 cardiovascular risk factor not adequately responding to secretagogues. C As per BSG 2021 guidelines, offer tegaserod, a 5-HT4 receptor agonist, as second-line therapy in patients with IBS-C in secondary care. Recognize that diarrhea is a common side effect. B As per CAG 2019 guidelines, consider avoiding the use of prucalopride to improve overall symptoms in patients with IBS-C. D Management of constipation, guanylate cyclase activators: As per ACG 2021 guidelines, offer guanylate cyclase activators (linaclotide and plecanatide) to improve global symptoms in patients with IBS-C. A https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 7/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway As per BSG 2021 guidelines, offer linaclotide or plecanatide, guanylate cyclase-C agonists, as second-line therapy in patients with IBS-C in secondary care. Recognize that diarrhea is a common side effect. A As per AGA 2020 guidelines, offer linaclotide in patients with IBS-C. A As per CAG 2019 guidelines, offer linaclotide to improve symptoms in patients with IBS-C. A Management of constipation, lubiprostone: As per ACG 2021 guidelines, offer chloride channel activators (lubiprostone) to improve global symptoms in patients with IBS-C. B As per BSG 2021 guidelines, offer lubiprostone, a chloride channel activator, as second-line therapy in patients with IBS-C in secondary care. Recognize that nausea is a common side effect. B As per AGA 2020 guidelines, consider offering lubiprostone in patients with IBS-C. C As per CAG 2019 guidelines, consider offering lubiprostone to improve symptoms in patients with IBS-C. C Management of constipation, tenapanor: As per AGA 2022 guidelines, consider offering tenapanor in patients with IBS-C. C As per BSG 2021 guidelines, offer tenapanor, a sodium-hydrogen exchange inhibitor, is an efficacious second-line therapy in patients with IBS-C in secondary care. Recognize that diarrhea is a common side effect. A 6. Nonpharmacologic interventions Exercise: advise all patients with IBS to take regular exercise. B Dietary modifications: As per AGA 2022 guidelines, offer dietary advice in patients with IBS having insight into their meal-related gastrointestinal symptoms and motivated to make the necessary changes. B Show 9 more As per ACG 2021 guidelines: Advise a limited trial of a low FODMAP diet to improve global symptoms in patients with IBS. B Consider advising consumption of soluble but not insoluble fiber to improve global symptoms in patients with IBS. B As per BSG 2021 guidelines, provide first-line dietary advice in all patients with IBS. B Show 4 more As per CAG 2019 guidelines, consider offering a low FODMAP diet to improve symptoms in patients with IBS. C Show 3 more Peppermint oil: https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 8/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway As per ACG 2021 guidelines, consider offering peppermint to improve global symptoms in patients with IBS. C As per BSG 2021 guidelines, consider offering peppermint oil for global symptoms and abdominal pain in patients with IBS. Recognize that gastrooesophageal reflux is a common side effect. C As per CAG 2019 guidelines, consider offering peppermint oil to improve symptoms in patients with IBS. C Psychotherapy: As per ACG 2021 guidelines, consider offering gut-directed psychotherapies to improve global symptoms in patients with IBS. C As per BSG 2021 guidelines: Consider offering psychological therapies when symptoms have not improved after 12 months of drug treatment. Consider referring at an earlier stage, if accessible locally, and based on patient preference. B Consider offering IBS-specific CBT or gut-directed hypnotherapy for global symptoms in patients with IBS. B As per CAG 2019 guidelines, consider offering CBT and hypnotherapy to improve symptoms in patients with IBS. C Herbal products: consider avoiding the use of herbal products to improve symptoms in patients with IBS. D Acupuncture: do not offer acupuncture to improve symptoms in patients with IBS. D 7. Therapeutic procedures Fecal microbiota transplantation: do not perform fecal transplantation to improve global symptoms in patients with IBS. D 8. Specific circumstances Patients with obesity: obtain an assessment of nutritional status (for malnutrition, sarcopenia, overweight, obesity) at the time of diagnosis and regularly thereafter (at least once a year) in patients with IBS. B Show 8 more 9. Patient education General counseling: educate patients about the diagnosis of IBS, its underlying pathophysiology and the natural history of the condition, including common symptom triggers. Introduce the concept of IBS as a disorder of gut-brain interaction, together with a simple account of the gut- https://web.pathway.md/diseases/recCvQdWQ2ZNIFCwL 9/12 6/24/23, 2:34 PM Irritable bowel syndrome Pathway brain axis and how this is impacted by diet, stress, cognitive, behavioral and emotional responses to symptoms, and postinfectious changes. B Show 2 more 10. Follow-up and surveillance Indications for referral: refer to gastroenterology in secondary care in case of diagnostic doubt, in patients with severe or refractory to first-line therapy symptoms, or if the patient requests a specialist opinion. B Management of refractory disease: review the diagnosis in patients with severe or refractory IBS symptoms and consider obtaining further targeted investigations. B Show 3 more Likelihood Ratios Pertinent positives The following findings increase the probability of irritable bowel syndrome in adults. -1 Finding LR+ Value Positive Kruis score ( 44) 7 Positive Rome I criteria 4.7 Positive Manning criteria 2.8 History of looser stools at onset of pain 2.1 (1.4-3.0) Show 4 more Pertinent negatives The following findings decrease the probability of irritable bowel syndrome in adults. -1 Finding LR- Value No history of lower abdominal pain 0.29 (0.12-0.72) Negative Manning criteria 0.3 Negative Kruis score (< 44) 0.3 Negative Rome I criteria 0.3 Show 4 more References 1. Brian E Lacy, Mark Pimentel, Darren M Brenner et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021 Jan 1;116 1 17 44. Open 2. Dipesh H Vasant, Peter A Paine, Christopher J Black et al. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. Gut. 2021 Jul;70 7 1214 1240. 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