IBS and Functional Bowel

• Audio chapter
  Single-voice audio, listen on the commute.
• ABIM-format MCQs
  5-option vignettes with full wrong-answer teaching.
• Study guide
  Tables, decision trees, primary sources.
• AI tutor
  Chapter-grounded, answers the question you're stuck on.

What this chapter covers

• Section 13.1: Definition and Rome IV diagnosis

  Irritable bowel syndrome is a positive clinical diagnosis built on a stereotyped symptom pattern, not a diagnosis of exclusion that emerges only after every organic possibility has been chased to ground.

• Section 13.2: Pathophysiology

  IBS is a disorder of brain-gut interaction, and the pathophysiology is easiest to hold if it is split along the two halves of the definition.

• Section 13.3: IBS-C treatment

  IBS-C treatment is layered, and the layers correspond to escalating mechanism-targeted intervention.

• Section 13.4: IBS-D treatment

  IBS-D treatment, like IBS-C, is layered, but the mechanisms targeted are different and several of the drugs carry important safety restrictions.

• Section 13.5: All-subtype treatments

  Several therapies work across IBS subtypes because they target shared mechanisms (visceral hypersensitivity, central pain processing, gut-brain signaling) that are not subtype-specific.

• Section 13.6: Bloating and pharmacology summary

  Bloating is the symptom IBS patients report as most bothersome, and it has two distinct mechanisms.

Podcast episodes

1. 01

   IBS and Functional Bowel: Constipation Subtype

   Irritable bowel syndrome with constipation is a positive diagnosis made from the symptom pattern, and one 34-year-old woman carries the case from first visit to treatment. The episode starts with the Rome IV criteria and then assigns the subtype from Bristol stool form on abnormal days. Next it checks alarm features and decides that no testing is needed without them, while screening for pelvic floor dyssynergia. It then explains her pain and constipation through visceral hypersensitivity and slow colonic transit. Treatment follows in steps: explanation, stopping constipating drugs, psyllium, polyethylene glycol, secretagogues, prucalopride, and pain-directed therapy.

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2. 02

   IBS and Functional Bowel: Diarrhea and Bloating

   Irritable bowel is a positive diagnosis, and treatment follows the mechanism that drives the symptoms. The episode starts with a young man with diarrhea-predominant disease: Rome IV diagnosis, subtype by Bristol form, alarm features, a narrow screen, and the treatable mimics that slip past it. Treatment then runs through loperamide, rifaximin, bile acid sequestrants, eluxadoline, alosetron, and low-dose tricyclics. The second patient has mixed-subtype IBS with fibromyalgia and migraines, so pain is treated through the gut and the brain, with peppermint oil, neuromodulators, and behavioral therapy. Bloating is worked up from the lumen outward, ending with abdomino-phrenic dyssynergia.

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Key topics

• ·Rome IV criteria
• ·Irritable bowel versus chronic constipation
• ·Subtyping by Bristol stool form
• ·Alarm features
• ·Testing in constipation-predominant disease
• ·Pelvic floor dyssynergia
• ·Visceral hypersensitivity and slow transit
• ·Fiber and polyethylene glycol
• ·Secretagogues
• ·Prucalopride and pain-directed therapy
• ·Rome IV diagnosis and subtype
• ·Alarm features and the narrow screen
• ·Mimics of diarrhea-predominant IBS
• ·Post-infectious IBS and C. difficile retesting
• ·Drugs for diarrhea-predominant IBS
• ·Eluxadoline and alosetron limits
• ·Visceral hypersensitivity and central pain
• ·Peppermint oil and neuromodulators
• ·CBT and gut-directed hypnotherapy
• ·Bloating workup and low-FODMAP diet
• ·Abdomino-phrenic dyssynergia