Laboratory and Microbiological Tests
Stool Tests
Stool tests can help detect gastrointestinal bleeding, intestinal inflammation, bacterial, viral or parasitic infections and other digestive system disorders. To ensure reliable results, it is important to collect the sample according to the instructions provided by the laboratory.
a) Faecal Immunochemical Test (FIT/iFOBT)
What is it?
FIT, or the faecal immunochemical test, is used in colorectal cancer screening programmes and in other situations where bleeding from the lower gastrointestinal tract is suspected.
How should you prepare?
- A special diet or stopping medicines is not usually required.
- Collect the sample according to the instructions supplied with the test kit.
- Store the sample and deliver it to the laboratory under the specified conditions.
- It is advisable to postpone the test during menstruation or if haemorrhoids are actively bleeding.
b) Faecal Calprotectin
What is it?
Calprotectin is a protein whose elevated level in the stool indicates intestinal inflammation. The test helps distinguish inflammatory bowel disease, such as Crohn’s disease and ulcerative colitis, from functional disorders such as irritable bowel syndrome. It can also be used to monitor disease activity and the effectiveness of treatment.
How should you prepare?
- No special diet is required.
- Collect the sample in a clean container intended for this purpose.
- Make sure that the sample does not come into contact with urine or toilet water.
- It is best to deliver the sample to the laboratory on the same day. If this is not possible, keep it refrigerated at 2–8 °C and deliver it according to the laboratory’s instructions.
- If you are due to have a colonoscopy, collect the sample before starting bowel preparation.
- Tell your doctor if you take non-steroidal anti-inflammatory drugs, such as ibuprofen, naproxen or diclofenac, as these medicines can sometimes increase the calprotectin level.
c) Microbiological and Parasitological Tests
What are they?
These tests are used to detect bacterial, viral or parasitic intestinal infections. Where necessary, the laboratory may perform a bacterial culture or test for toxins, viruses or parasites.
How should you prepare?
- Collect the sample in a sterile container supplied or recommended by the laboratory.
- Make sure that it does not come into contact with urine or toilet water.
- It is best to deliver the freshest possible sample to the laboratory or follow the specific laboratory’s instructions regarding storage and transport.
- Detecting certain parasites may require 2–3 samples collected on different days because parasites or their eggs are not passed continuously.
- If possible, avoid taking antibiotics, bismuth preparations, laxatives or antidiarrhoeal medicines before the test unless your doctor has instructed you otherwise.
d) Faecal Pancreatic Elastase
What is it?
Pancreatic elastase is an enzyme whose level in the stool helps assess exocrine pancreatic function, meaning whether the pancreas produces enough digestive enzymes. The test is important when chronic pancreatitis, exocrine pancreatic insufficiency or digestive problems caused by certain other conditions are suspected.
How should you prepare?
- No special diet is required.
- Collect the sample in a clean container intended for this purpose.
- Make sure that the sample does not come into contact with urine or toilet water.
- It is advisable to deliver the sample to the laboratory as soon as possible or store it according to the laboratory’s instructions.
- Pancreatic enzyme preparations, such as pancreatin, do not need to be stopped before the test because they do not affect the result.
- It is best to perform the test using a formed stool sample because very watery stools may produce a falsely low elastase level.