Diarrhea Study Guide | Let's Talk Medicine

Diarrhea: Acute, Sub acute, & Chronic

Study guide:

Definition:

It is the passage of loose\watery stool at least 3 times per 24 hours (>200 ml).

Classification based on duration:
- Acute: <2 weeks
- Sub-acute: 2-4 weeks
- Chronic: >4 weeks
Classification based on etiology: mainly for acute
- Community acquired
- Nosocomial/ Hospital-acquired

Acute:

Community acquired:
- Viral:
  - Rotavirus
  - Norovirus
- Bacterial:
  - SEVERE WATERY DIARRHEA:
    1. Mechanism:
      - Fluid loss from the proximal small intestine without cellular injury.
    2. Course:
      - Acute, brief 1-3 days
      - Self limited.
    3. Common microorganisms:

DYSENTERY (BLOODY) DIARRHEA:
1. Primary site for colonization: colon.
2. Characteristics:
  - Diarrhea in smaller volume than in watery diarrhea BUT lasts longer.
  - Diarrhea with BLOOD + PUS.
  - Inflammation and/or distinctive changes in the colonic mucosa.
3. Presents as: fever, abdominal pain and cramps, & tenesmus.
  - Most cases resolve spontaneously in 2-7 days.
4. Common pathogens:

Note: CHESS commonly cause bloody stool: Campylobacter, Hemorrhagic E.coli, E.histolytica, Salmonella, Shigella.

ENTERIC FEVER (TYPHOID FEVER):
1. Salmonella enterica serovar typhi.
2. Presents as: gradual onset of a systemic infection with fever and abdominal pain"(diarrhea is not a constant feature!)

DIARRHEAL DISEASE WITH VOMITING AS A PROMINENT FEATURE:

Nosocomial/ Hospital-acquired:
- Infants:
  - Rotavirus -> winter time, breakouts.
  - Enteropathogenic E.coli (EPEC): infantile diarrhea.
- Adults:
  - Antibiotic associated diarrhea:
    1. S\E of antibiotics (erythromycin, augmentin, cephalexin, Clindamycin)
    2. C.difficile overgrowth (takes 3 days).
  - Non- antibiotic associated diarrhea:
    1. CT contrast.
    2. Laxatives, magnesium, and sorbitol.
    3. Tube feed diarrhea

Sub-acute:

Travelers’ diarrhea: ingestion of fecally contaminated food, water, or ice.

Causes:
1. 80% is bacterial cause.
2. 50% of all cases: Enterotoxigenic E.coli.
3. 10%-20% of cases: Shigella.
4. Other: campylobacter jejuni.

Diagnosis of Acute & Subacute Diarrhea:
- Exclude infection (stool study) GOLD STANDARD for acute diarrhea.
- Checking for: mucus, blood (RBCs), WBCs.
- If negative go for Endoscopy.

Management of Acute & Subacute Diarrhea:

Chronic:

Classified according to the characteristic of stool:
SECRETORY:
1. Mechanism:
  - Derangement of electrolyte and fluid transport across the intestinal epithelium.
  - (Special channels in the walls are disturbed).
2. Etiology:
  - Medication: ethanol, stimulant laxatives.
  - Anatomical defects (bowel resection) and Congenital (chloridorrhea, mucosal defect…).
  - Toxins (e.g. vibrio cholera).
  - Hormones & neuroendocrine tumors (e.g. VIPoma, gastrinoma…).
3. NOT affected by FASTING!

OSMOTIC:
1. Mechanism:
  - Osmotically active solute: driving water into the lumen.
2. Etiology:
  1. Osmotic laxatives (poorly absorbed ions: Mg++, SO4+).
  2. Non-absorbable sugars (artificial sweeteners, lactose intolerance).
3. Gets better with FASTING!

FATTY
- Characteristics: malodourous, bulky stool, difficult to flush
  - Floating is due to gas not fat.
- Mechanism:
  - Mal-absorption:
    - Mucosal diseases (celiac disease)
    - Short bowel syndrome (after surgery)
  - Mal- digestion:
    - Pancreatic insufficiency (chronic pancreatitis)
    - Cholecystectomy:
      - Mechanism: bile will drain directly into small intestine -> exceed the terminal ilium absorptive capacity -> too much bile reaching the colon -> diarrhea
  - Post-mucosal lymphatic obstruction.

INFLAMMATORY
- Presents as: pain, fever, cramps, and bloody diarrhea.
- Etiology:
  1. Inflammatory bowel disease (IBD) -> crohn’s disease, and ulcerative colitis.
  2. Infections (C. diff colitis, Yersinia, TB)
  3. Always exclude infection in inflammatory (bloody) diarrhea, even if you are sure of your diagnosis.

Osmotic Gap 50-100 mosm \ Kg

> 100 Osmotic Diarrhea

normal pH: 7-7.5

pH high

pH low

Ions

Sugar

<50

Secretory Diarrhea

MOTILITY DISORDER
- Etiology:
  1. Diabetic neuropathy à disturbance in symp. / parasymp.
  2. Hyperthyroidism à bowels hyper-motile
  3. Addison’s disease
  4. Irritable Bowel Syndrome (IBS):

A. Mechanism: stress -> hyperactive colon.
B. More in females.
C. Presentation: chronic lower abdominal PAIN+ changes in the bowel habits (diarrhea, constipation, or both).
D. Dx.: Manning and Rome criteria.

Diagnosis of Chronic Diarrhea:
- CBC: looking for leukocytosis.
- Chemistry: looking for electrolyte disturbances.
- Stool: occult blood.
- Fecal leukocyte: suggestive of infections.
- Biopsy for inflammatory bowel disease.
Management of Chronic Diarrhea:
- Treat the underlying cause
- Symptomatic

References:

Kumar P, Clark M. Kumar & Clark's clinical medicine.
Le T, Krause K. First aid for the basic sciences. New York: McGraw-Hill Medical; 2012.
Le T, Bhushan V, Singh Bagga H. First aid for the USMLE step 2 CK. New York: McGraw-Hill Medical; 2010.
Bergin J. Medicine recall. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2008.
Collins P, Fox C. Gastroenterology. Edinburgh: Mosby; 2008.
Fischer C. Master the boards.
Agabegi S, Agabegi E, Ring A. Step-up to medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins; 2013.

Written by: Haifa Al-Issa
Reviewed by: Roaa Amer
Haneen Al-Farhan
Format Editor: Roaa Amer

Website publisher: Salman Alahmed

Bayan Alzomaili