Stool Collection is the process of collecting stools sample in the stool container for laboratory diagnosis purposes. You can not perform Stool Analysis without Collecting of stool sample First, and this performed during pre analytical Phases.
In this article you will learn:
- Introduction of Stool
- Materials for stool collection
- Procedure for Stool collection
Introduction of Stool
- Stool is a waste material excreted from the intestines,
- Stool examination is used to identify parasites causing several infections and infestations.
- The identification of parasites can also assist in the control of local parasitic infection.
Materials Used to Collect Stool Specimen
- Stool Container that have spoon inside.
- Sticker or marker pen for labelling
Collection of Stool Specimen
- For stool examination, a fresh specimen is collected in a clean, dry and leak-proof container.
- The specimen should not be contaminated with urine, so be sure to instruct the patient correctly.
- The collection of several specimens on alternate days may be required to detect parasites.
Give a patient a specimen collection container and a spatula and instruct collect to collect the stool specimen as follows:
You have been asked to collect a stool specimen for laboratory analysis.
- Please wash your hands before beginning the procedure.
- DO NOT pass the specimen into the toilet
- DO NOT pass the specimen directly into the collection vial.
- DO NOT urinate on the specimen or into the collection vial.
- DO NOT allow any water to mix with the specimen.
- Pass the stool specimen into any clean and dry container such as a bedpan, plastic plate, or newspaper.
- Carefully open a specimen collection container.
- Using the wooden spatula, collect small amounts of stool from areas that are slimy, watery, or bloody and place them into a specimen collection container.
- If the stool is hard, collect small amounts from both ends and the middle and place into a specimen collection container.
- Fill the specimen collection container with enough specimen (About 1 spoonful or 10ml if it is a liquid specimen.)
- Obtain a stool sample (in the container) from a patient. Adhere to infection prevention and control standards.
- Write patient’s name, date, & time of collection on the container.
- The specimen must be transported as soon as possible to the lab and must be accompanied by a doctors request form.
- Stool samples must be examined within one hour after collection.
Macroscopic examination of stool sample
- A macroscopic examination reports the physical appearance of a specimen.
This includes a description of:
- colour (yellow, brown or black)
- consistency (formed, semi formed, watery or rice water)
- visible contents (blood, mucus or worms)
- Color of Stool
Normal Stool: Appears brownish due to the presence of stercobilinogen. Stool from infants appear yellow brown or yellow green.
- Colourless Stool: Pale coloured stool is due to the absence of stercobilinogen as a result of obstructive jaundice, abnormal fat absorption in the intestine as that occurs during Giardiasis.
- Brown/Black Stool: Can be a result of iron therapy, gastro intestinal bleeding or hookworm infection.
Consistency of Stool
- Normal Stool: Usually well formed.
- Unformed, Semiformed/Watery Stool: Indicates bacterial or parasitic infection.
- Rice Water Stool: Indicates cholera.
Visible Contents in Stool
- Normal Stool: Usually have no visible abnormal contents.
- Blood in Stool: May be due to certain parasites (e.g. Entamoeba histolytica, Schistosoma mansoni) or to bacteria(Shigella sp. Enterohemorrhagic Escherichia coli) or colonic or rectal malignancies.
- Mucus: Usually due to Entamoeba histolytica, tumour, dysentery or bacterial infection.
- Worms: Worms or segments of worms may be seen when Ascaris, Taenia or Enterobius vermicularis are the causative agents of the infection.
Microscopic Examination of Stool
- Saline and Iodine Preparation of Stool (Wet Mount/Wet Preparation/Saline Mount)
- Routinely stool specimens are examined using the saline and iodine preparation to detect parasites, cysts and cells.
- After the macroscopic examination the stool specimen is prepared as follows:
- Place a drop of saline near one end of a slide and a drop of iodine near the other end.
- Iodine is used to stain the nuclear structure of cysts e.g. that of Entamoeba histolytica(four nuclei) and Entamoeba coli (eight nuclei).
- Using a wooden applicator stick, mix a small amount of specimen with the saline and a similar amount with the iodine to make a smooth thin preparation and cover with a cover glass.
- Examine the slide systematically, first using the 10X objective with the iris sufficiently closed to give good contrast.
- Use 40X objective to examine in greater detail after parasite/cyst/ova is seen.
- Report your findings.
- White blood cells (WBC): Few, moderate or many WBC seen.
- Red blood cell(RBC): Few, moderate or many RBC seen.
- Ova of parasites including Hookworm, Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, Schistosoma mansoni and Taenia: Report number of ova seen.
- Giardia lamblia: Report as Giardia lamblia seen.
- Strongyloides stercoralis larvae: Report as Strongyloides stercoralis seen.
- Entamoeba histolytica cyst: Report as Entamoeba histolytica cyst seen.
- Entamoeba histolytica trophozoites: Report as Entamoeba histolytica trophozoites seen.
- Pus: Increased number of pus cells can be seen in stool from patients suffering from dysentery and other gastrointestinal infections.
WBCs seen in Stool analysis as a wet Preparation: Image source
RBCs seen in Microscope
Interpretation of Results
- White blood cells (WBC): May indicate infection.
- Red blood cell(RBC): Many RBC can indicate infection or bleeding.
- Ova of parasites including: Hookworm Ascaris lumbricoides Trichuris trichiura, Enterobius vermicularis, Schistosoma mansoni and Taenia: Indicates Parasitic infection.
- Giardia lamblia: Giardiasis.
- Entamoeba histolytica cyst or trophozoite: Indicates Dysentry.
- Strongyloides stercoralis larvae: Strongyloidiasis.
- Carter J, Lema.O. (1994) Practical laboratory manual for health centres in Eastern Africa. AMREF.
- Cheesbrough M. (1998). District Laboratory Practice in Tropical Countries. Part 1. Tropical Health Technology, Gapson Papers Ltd, NOIDA, India.
- Cheesbrough M. (2000). District Laboratory Practice in Tropical Countries. Part 2. Tropical Health Technology, Cambridge University Press UK.
- Cheesbrough M. (1987). Medical Laboratory Manual for Tropical Countries. Volume 1 2nd Ed. ELBS Butterworth, Heinemann Ltd, Oxford.