Pelvic Floor and Anorectal Disorders

• 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.
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What this chapter covers

• Section 16.1: Chronic constipation: definitions and empiric management

  Chronic constipation is a diagnosis built on symptoms rather than on stool frequency alone, because the population that complains of constipation is dominated by patients who pass stool more than three times a week and still report straining, hard stools, incomplete evacuation, and dependence on manual maneuvers.

• Section 16.2: Prescription therapies for refractory CIC

  Prescription therapy in chronic idiopathic constipation begins when fiber, polyethylene glycol, and stimulant laxatives have failed to produce a satisfactory response, and the choice among the available drugs is mechanism-driven.

• Section 16.3: Defecation disorders and biofeedback

  Defecatory disorders are the diagnoses to consider when a constipation patient has failed empiric therapy, because the mechanism is mechanical rather than transit-related and the right intervention is biofeedback rather than additional laxatives.

• Section 16.4: Slow-transit constipation

  Slow transit constipation is the diagnosis that emerges after a defecatory disorder has been excluded and the patient still has infrequent bowel movements and refractory symptoms.

• Section 16.5: Opioid-induced constipation and PAMORA

  Opioid-induced constipation is mechanistically distinct from chronic idiopathic constipation, and that distinction matters because the right drug class differs.

• Section 16.6: Fecal incontinence

  Fecal incontinence is the involuntary loss of solid or liquid stool, distinct from anal incontinence (which includes flatus) and from seepage (passage of small amounts of stool residue, typically in patients with internal sphincter dysfunction or perianal soiling).

• Section 16.7: Hemorrhoids, anal fissure, and pruritus ani

  The benign anorectal disorders that bring patients to clinic are anatomically distinguished by their relationship to the dentate line, and the differential should be anchored to that anatomic landmark before reaching for a diagnosis.

Podcast episodes

1. 01

   Chronic Constipation Pharmacology and OIC

   Episode one of the Pelvic Floor and Anorectal Disorders chapter works through chronic constipation as a symptom-defined syndrome, the empiric laxative sequence that resolves most patients, and the prescription drugs for refractory disease mapped to four molecular targets. The organizing idea: match the drug to the mechanism, and keep opioid-induced constipation separate because the enteric receptor never develops tolerance. Definitions, alarm features, secondary causes, secretagogues, prucalopride, and the peripherally acting opioid antagonists throughout, all framed around the exam stem that names the mechanism.

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2. 02

   Transit Constipation

   Episode two covers the constipation phenotypes that need more than pharmacology: defecatory disorders diagnosed on anorectal manometry and balloon expulsion and treated with biofeedback, and slow-transit constipation documented on a marker or capsule study. The organizing discipline is to decide the mechanism before the next drug, because escalating laxatives in unrecognized outlet dysfunction produces overflow and urgency without relief. The central pitfall runs the whole episode: unrecognized outlet dysfunction falsifies the transit study and sends the wrong patient to colectomy, so check the outlet before you cut the colon. Testing thresholds, the two-of-three diagnostic rule, and precise colectomy criteria throughout.

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3. 03

   Fecal Incontinence and Benign Anorectal Disorders

   Episode three covers fecal incontinence managed in a fixed sequence and the benign anorectal disorders anchored to the dentate line. Incontinence rarely fails for a single reason, so the workup canvasses the whole continence stack and the treatment runs from optimizing the modifiable factor through loperamide and biofeedback to sacral neuromodulation, which has displaced sphincteroplasty as first-line surgery for refractory disease. The benign disorders follow the anatomy: above the dentate line means painless bleeding, below it means sharp pain, and that landmark predicts management for hemorrhoids, anal fissure, and pruritus ani. Manometry, endoanal ultrasound, the seventy-two-hour rule, and the atypical-fissure workup throughout.

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Key topics

• ·Symptom-defined diagnosis of chronic constipation
• ·Three mechanistic subtypes: normal-transit, slow-transit, defecatory
• ·Alarm features and secondary causes
• ·Empiric sequence: diet, fiber, osmotic, stimulant laxatives
• ·Prescription secretagogues and their four targets
• ·Prucalopride as the serotonin-4 prokinetic
• ·Opioid-induced constipation and tolerance asymmetry
• ·Peripherally acting opioid antagonists and the obstruction contraindication
• ·Deciding phenotype before the next drug
• ·Dyssynergic defecation mechanism and rectal exam clue
• ·Balloon expulsion screening test
• ·Anorectal manometry parameters and the rectoanal inhibitory reflex
• ·Defecography and structural lesions
• ·Two-of-three diagnostic rule and biofeedback
• ·Slow-transit constipation and transit studies
• ·Subtotal colectomy indications and disqualifiers
• ·The continence stack and multifactorial failure
• ·Etiologic grid: sphincter, rectal, neurologic, consistency, overflow
• ·History and targeted testing with manometry and endoanal ultrasound
• ·Fixed treatment sequence from modifiable factors to loperamide and biofeedback
• ·Sacral neuromodulation versus sphincteroplasty
• ·Internal and external hemorrhoids and the dentate line
• ·Anal fissure mechanism and atypical-location workup
• ·Pruritus ani as a symptom, not a diagnosis