Approach to Diarrhea

• Approach to diarrhea

Objectives

• Define chronic diarrhea
• Contrast small and large bowel diarrhea
• Distinguish between osmotic and secretory diarrhea, motility disorders, and malabsorption
• Recognize common illnesses within each pathophysiologic category

Amplification of Surface Area

• The goal in the small intestine is to increase surface area for absorption
• This is achieved through structures like plica circulares, villi, and microvilli to enhance nutrient absorption

Chronic Diarrhea

• Definition is based on frequency versus physical signs
• It's vital to differentiate urgency from incontinence in chronic diarrhea

Diarrhea: Small vs. Large Bowel Origin

• Pathology in the small bowel often results in a larger stool volume compared to large bowel diseases
• Decreased absorption and increased secretion are key factors
• Location of abdominal pain helps determine if the origin is small bowel (midgut-periumbilical) or hindgut/large bowel (suprapubic)

Acute Diarrhea

• Usually infectious and self-limiting in nature
• Anti-infective therapy isn't required in most cases
• Antibiotics are not shown to shorten duration of illness

Chronic Diarrhea

• Has multiple potential mechanisms
• Frequency, pain location, tenesmus, systemic symptoms, and extraintestinal features should be asked about

Diarrhea Types

• Osmotic diarrhea produces bulky, foul-smelling stools and lessens with fasting
• Secretory diarrhea produces watery, continuous stools
• Inflammatory diarrhea produces bloody, mucopurulent, continuous stools
• Motility-related diarrhea

Specific Diarrhea Types and Causes

• Osmotic diarrhea can be caused by lactose intolerance, celiac disease, and chronic pancreatitis
• Secretory diarrhea can be caused by cholera, traveler's diarrhea, and pseudomembranous colitis
• Inflammatory diarrhea can be caused by inflammatory bowel disease and infections
• Motility-related diarrhea can be caused by irritable bowel syndrome

Approach to Diarrhea Diagnosis

• Conduct a detailed history and physical examination
• In the absence of "red flags," always consider Irritable Bowel Syndrome (IBS) as a possibility
• In the presence of "red flags," concentrate on the area of concern and arrange investigations accordingly

Irritable Bowel Syndrome (IBS) - Rome Criteria

• Abdominal discomfort must be present for at least 12 weeks (non-consecutive) in the preceding 12 months
• Pain needs to have at least two of these three features: relieved with defecation, onset associated with a change in stool frequency, onset associated with a change in stool appearance

Irritable Bowel Syndrome (IBS) Symptoms

• Cumulative symptoms supporting an IBS diagnosis include
  • Abnormal stool frequency
  • Abnormal stool form (lumpy/hard or loose/watery)
  • Abnormal stool passage (straining, urgency, or incomplete evacuation)
  • Passage of mucus
  • Bloating or abdominal distension

Irritable Bowel Syndrome (IBS) - Dietary History

• Always take a dietary history
• Identify food intolerances like lactose, fructose, gluten
• Consider also food allergies and fiber deficiency
• Note the use of food substitutes like artificial sweeteners, and drugs like caffeine, nicotine, and prescription drugs

World Prevalence of IBS

• Ranges geographically, with varying percentages of the population affected
• North America: 8-15%
• UK: 14%
• Brazil: 15%
• Spain: 19%
• China: 23%
• New Zealand: 16%
• Other countries: 9%

Prevalence of IBS in North America

• Reaches up to 30% in certain regions
• Subgroups include:
  • Constipation dominant (1/3)
  • Diarrhea dominant (1/3)
  • Alternating (1/3)

FODMAP Diet

• Involves restricting fermentable oligo-, di-, mono-saccharides, and polyols
• High FODMAP foods include:
  • Fructose (many fruits, honey, corn syrup)
  • Lactose, fructans (wheat, onion, garlic)
  • Galactans (beans, lentils, legumes)
  • Polyols (artificial sweeteners, stone fruits)
• The approach involves eliminating all FODMAPs and then reintroducing them one at a time

Gluten Sensitivity

• Gluten itself can trigger gut symptoms and fatigue, independently of celiac disease
• Research indicates gluten can cause gastrointestinal symptoms in people without celiac disease

Probiotics

• Demonstrated only modest benefits in short-duration studies with small subject numbers using varying preparations
• Generalizability is an issue
• Natural probiotic experiments involve intestinal worm infections and fecal enemas

Probiotics - AGA CPG 2020 Guidelines

• Probiotics for patients with CDI, CD, UC, and IBS are only recommended in clinical trials
• Probiotics are not recommended for children with acute infectious gastroenteritis
• An eight-strain combination probiotic is suggested for patients with pouchitis (Lacto, Bifido, Strepto)

Algorithm for Managing IBS

• Involves excluding red flag symptoms then taking a history with clinical examination
• Rule out malignancy if necessary
• Make a positive diagnosis
• Educate patient and reassure them of a therapeutic partnership

IBS Algorithm - Subtypes

• Identify IBS Subtype if possible
• Diarrhea is subtyped to pain or bloating features and treated differently
• Mixed-Subtype IBS
• Constipation Predominant IBS

IBS algorithm - Potential Medical Treatments

• Opiod receptor agonists Loperamide, Eluxadoline
• Prosecretory agents for constipation predominant Linaclotide, Lubiprostone, Prucalopride
• Antibiotics Rifaxamin

Approach to Diarrhea Re-evaluation

• History and physical exam are essential
• If incomplete response to any treatment, reassess patient
• Review drug history for NSAIDs, Metformin, and PPIs
• Conduct tTG and fecal calprotectin tests to check for inflammation, check Neutrophil cytoplasmic protein and CRP

Diverticulosis

• Usually asymptomatic
• Prevalent in industrialized countries
• Common complications include hemorrhage and diverticulitis
• Might also lead to perforation or fistula formation
• Not a part of IBS

Diverticulosis - General Management

• Eat a normal diet
• Don't believe the myth that nuts or seeds are bad for you, they are good for you
• Treatment involves
  • Antibiotics for infections
  • Endoscopy or angiography for bleeding
  • Surgical management

Secretory Diarrhea

• Causes include endocrine (hormone-secreting) tumors
• Infections
• Cholera, travelers diarrhea, PMC
• Bile salt mediation

Treatment of PMC

• Flagyl
• Vancomycin
• Fidaxomycin

Common Causes of Chronic Diarrhea

• IBS
• Celiac disease
• Bile acid diarrhea
• Diet (FODMAP, caffeine, alcohol, licorice)
• Drugs (antibiotics, NSAIDs, Mg supplements, Metformin, gliptins)

Infrequent Causes of Chronic Diarrhea

• SBBO
• Post surgical complications
• Microscopic colitis
• Chronic pancreatitis
• Radiation enteropathy
• Hyperthyroidism
• Diabetes

Rare Causes of Chronic Diarrhea

• Other enteropathies
• Hormone secreting tumors

Approach to IBS Investigation when Management is Suboptimal

• Consider fecal calprotectin
• TTg if not already done (don’t forget IgA)
• If endoscopy is performed, always do biopsies
• During gastroscopy, biopsy the bulb and distal duodenum (minimum 4 samples)
• During colonoscopy, biopsy the right and left colon