Irritable Bowel Syndrome

Female pt with h/o functional abdominal pain presents with acute on chronic abdominal pain x6 months. Cramping pain has occurred ≥3 days per month during the past 2-3 months (see notes) and is associated with change in frequency/consistency of stools. Pain improves with defecation, but pt often experiences sensation of incomplete evacuation. Mucous sometimes present in stool, but no hard/bloody/tarry stools. Denies fever, unintentional weight loss, dysphagia/dysphagia, vomiting, back pain, dysuria. No family h/o Celiac disease, IBD. Afebrile and appears anxious on exam.

  • Consider CBC, TSH, CRP, ESR

  • Rule out Celiac disease: Consider anti-tissue transglutaminase IgA

  • Rule out GI bleed/alternative diarrhea etiologies: Consider FOBT and/or fecal ova/parasite testing

  • Consider abdominal x-ray

  • Pain persisting for >1 year: Consider referral for EGD

Treatment for Pediatric and Adult Patients

  • Recommend exercise and CBT

  • Diarrhea-predominant symptoms

    • Hydrolyzed guar gum 5g qd

    • Peppermint oil capsules TID

    • Probiotics: Recommended Kefir PO

    • Refractory symptoms

      • Consider loperamide 0.25-0.5 mg/kg/day in 2 divided doses

      • Consider rifaximin 600mg

  • Constipation predominant symptoms: See pediatric functional constipation

  • Counseling for parents of pediatric patients

    • Parents advised to validate symptoms but avoid reinforcing symptoms with secondary gain, e.g. missing school

    • Parents counseled that symptoms generally resolve over the course of several months

Additional Treatment Options for Adults

  • Diarrhea and/or constipation predominant symptoms

    • Antidepressant: Fluoxetine 20 mg qd; increased to 40 mg qd for refractory symptoms

    • Antispasmotic: Dicyclomine (Bentyl) 20 mg 4 times daily x7 days; after 1 week, increase to 40 mg 4 times daily if necessary

  • Constipation predominant symptoms

    • Neomycin 4g qd

    • Lubiprostone (Amitiza): Start 8 mcg BID and increase to 24 mcg BID for severe, refractory symptoms

Notes

  • Peak onset occurs between 20 and 40 years old

  • 1.5 times more common in females

  • Diagnosis

    • Based on Rome Criteria that include

      • Recurrent abdominal pain + two or more symptoms at least 1 day per week during the past 3 months

      • Additional symptoms include pain with defecation, change in stool frequency/form, etc.

    • Pediatric patients: Only 2 months of symptoms required vs. 3 months in adults

    • Describe stools using the Bristol Stool Scale

    • Most labs are not useful in diagnosis and should only be considered if history suggests an alternate etiology