PANCE Blueprint GI and Nutrition (8%)

Patient will present as → a 40-year-old woman who comes to your office with a several-year history of lower abdominal pain associated with constipation (one hard bowel movement every 3 days) and frequent mucus discharge. She states that her abdominal pain is better after a bowel movement. She has never passed blood per rectum. She describes no fever, chills, weight loss or gain, jaundice, or any other symptoms. There is no relationship between the abdominal pain and specific food intake. On physical examination, the abdomen is scaphoid, and no hepatosplenomegaly or masses are palpated. There is a mild generalized abdominal tenderness, but it does not localize.

Irritable bowel syndrome is a chronic disorder of gut–brain interaction (a functional gastrointestinal disorder) characterized by recurrent abdominal pain associated with altered bowel habits, made as a positive clinical diagnosis using the Rome criteria when there are no alarm features and limited testing is normal — it is not a diagnosis of exclusion.

IBS subtypes are based on the predominant stool form on days with abnormal bowel movements (Bristol Stool Form Scale):

• IBS with predominant constipation (IBS-C): more than 25% of bowel movements are hard or lumpy (Bristol types 1–2)
• IBS with predominant diarrhea (IBS-D): more than 25% of bowel movements are loose or watery (Bristol types 6–7)
• Mixed IBS (IBS-M): more than 25% hard or lumpy and more than 25% loose or watery
• Unclassified IBS (IBS-U): Patients who meet diagnostic criteria for IBS but cannot be accurately categorized into one of the other three subtypes

IBS is a disorder of gut–brain interaction: altered gut motility, visceral hypersensitivity, changes after an episode of gastroenteritis (post-infectious IBS), shifts in the gut microbiome, and stress all contribute

• Bloating, gas, and mucus in the stool are common
• Pain is related to defecation (usually eased, sometimes worsened, by a bowel movement)
• Bowel movements are irregular and vary from constipation to diarrhea

The diagnosis of IBS can reasonably be made using the Rome criteria as long as patients have no red flag (alarm) findings, such as symptom onset at age 45 or older, rectal bleeding, nocturnal diarrhea, progressive pain, unexplained weight loss, iron deficiency anemia, elevated inflammatory markers, or a family history of inflammatory bowel disease (IBD), colorectal cancer, or celiac disease. IBS is a positive diagnosis, not a diagnosis of exclusion.

• Patients with a red flag finding need further evaluation, usually colonoscopy
• Testing is limited: Complete blood count (CBC) and age-appropriate colorectal cancer screening for everyone; with diarrhea, add fecal calprotectin (or lactoferrin), a Giardia stool test, and celiac serology (tissue transglutaminase IgA). Results are normal in IBS

Treat the dominant symptom. Start with education, reassurance, and diet, then add medication.

• Everyone: regular exercise and stress management, soluble fiber (psyllium) — not insoluble fiber like wheat bran, which worsens bloating — and a time-limited low-FODMAP diet trial with planned food reintroduction
• Pain and cramping: peppermint oil, antispasmodics (dicyclomine, hyoscyamine), or a low-dose tricyclic antidepressant (nortriptyline, amitriptyline); gut-directed psychotherapy (cognitive behavioral therapy, hypnotherapy) also helps
• IBS-C: polyethylene glycol (PEG) eases constipation but not pain → secretagogues: linaclotide or plecanatide (guanylate cyclase-C agonists), lubiprostone (chloride-channel activator), or tenapanor
• IBS-D: loperamide (firms stools but does not help pain), rifaximin (nonabsorbable antibiotic for bloating and global symptoms), eluxadoline (avoid after cholecystectomy, with heavy alcohol use, or with prior pancreatitis), and alosetron (only for women with severe, refractory IBS-D — risk of ischemic colitis)
• Not recommended: probiotics (inconsistent benefit), SSRIs as primary therapy (use only for coexisting anxiety or depression), and tegaserod (withdrawn from the US market)