Acute Diarrhea
Ischemic
Infectious
Inflammatory
Non-Bloody
Nausea/Vomiting 
Predominant
Bloody
> 2-3 loose stools/day, > 175-235g/day, > 48 hours, < 14 days
Diarrhea Predominant
• Bacilus cereus
• Staphylococcus aureus
• Crohn’s Ileitis
• Crohn’s Colitis
• Viral
• Bacterial (eg. C. perfringens, 
V. cholerae, E. coli, 
Salmonella, Yersinia)
• Parasitic (eg. Giardia)
• Drugs (Antibiotics, Laxatives, 
Antacids)
• Toxins
• Bacterial (eg. E. coli, C. 
difficile, Salmonella, 
Campylobacter, Shigella)
• Parasitic (eg. E. histolytica)
**C. difficile is under “large bowel” but presents with non-bloody diarrhea 
usually
Ischemic colitis is a self-limiting illness in most (due to vascular network 
from SMA, IMA, iliacs) whereas small bowel ischemia is an abdominal 
catastrophe (only one supply, SMA)
• Ulcerative Colitis
• Crohn’s Colitis
Dietary
Bloody/Pain/Small 
Volume/Urgency 
(Large Bowel)
Watery/Large Volume 
(Small Bowel)