STOOL COLLECTION & TESTING

Ira Shah
Consultant Pediatrician – B.J.Wadia Hospital for Children
Editor - Pediatric Oncall

Why is stool needed for testing?
Most of the time, stool is needed for testing in patients with diarrhea. Stool can be tested to check for bacteria (such as E. coli, shigella, cholera), viruses (such as rotavirus, adenovirus) and even parasites (amoeba, giardia, cryptosporidia). In patients suspected to have worms in the tummy stool can be tested to look for eggs of various worms such as roundworms, hookworms, pinworms and tapeworms.

In patients with chronic diarrhea, stool can be tested to look for fat, reducing substance and pH. Normally stools contain no fat, no reducing substance and are alkaline. Presence of fat in stool may suggest malabsorption, presence of reducing substance and acidic stools may suggest lactose intolerance and intolerance to milk. Blood in stools may occur with dysentery, amoebic infection or ulcers and even a bleeding problem or liver problem. Occasionally, in patients suspected to have polio, stool may be tested to look for poliovirus.

How is the stool collection done?
Stool should be collected in a clean, dry plastic jar with screw cap / lids. These jars can be obtained from the hospital or laboratory. One can also use any clean similar container from the home. The stool should be collected directly into the container and not by fishing out of the toilet or from a pan. Make sure no urine contaminates the stool sample.

How soon should the stool be sent to the laboratory?
The stool should be sent to the laboratory right away. If it is not possible, it should be refrigerated.

Why do doctors sometimes ask for 3 stool samples to be tested?
Normally one stool sample may identify most of the problems one is looking for. However in cases of certain parasites or worms, one may need to look at three samples taken on 3 consecutive days to get a better yield. This is because complete intestinal clearance of stool may take 72 hours and parasites may be present in any of the 3 stool samples and not necessarily in the first one.

Last updated on 24^th December 2009