Investigation of case of diarrhea

1.Examination of the stool

a.Presence of WBC in stool is suggestive of intestinal inflammation as a result of a mucosal invasion with bacteria, parasite or toxin and this is also seen in ischaemic colitis and IBD(inflammatory bowel disease)

b. Absence of leucocytes in the stool is suggestive of non- inflammatory, non-invasive process (viral infection, giardiasis, drug related)

c. Occult or gross blood in the stool indicates the following

• Presence of a colonic neoplasm
• An acute ischaemic process
• Radiation enteritis
• Ameobiasis 
• Severe mucosal inflammation

d.Bacteria and parasitic organisms: Fresh stool sample must be examined for the presence of ova and parasites. Organisms that colonise the upper gastrointestinal tract may not be found in stool sample and duodenal or jejunal aspirates or biopsies or the string test may be required.

e. Stool culture will help to determine the bacterial pathogens in most diarrhea cases. Special techniques are necessary. Example for detection of Yersinia, Campylobacter.

2. Sigmoidoscopy or Colonoscopy:

 It is useful in evaluation of

a. Bloody diarrhoea

b. Diarrhoea of uncertain aetiology

c. Inflammatory bowel disease, pseudomembranous colitis, pancreatic disease or laxative abuse (melaenosis coli).