Fecal occult blood test

A faecal occult blood test is mainly done to screen for colon cancer in people over the age of 50 or to those who have a family history of this cancer.

It is also used to diagnose gastrointestinal conditions that may cause tissue damage and leakage of blood. 

Blood in stool may occur due to the following conditions:

• Gastric ulcers 
• Inflammation of the lower rectum
• Rectal tumour
• Inflammatory bowel disease (IBD)
• An adverse effect of medications such as NSAIDs
• Vigorous exercising 

A faecal occult blood test may also be ordered if your doctor suspects that you have anaemia and show the following symptoms:

• Fatigue
• Weight loss
• Lightheadedness
• Abdominal pain

Your doctor will ask you about your family history, to determine the cause of your symptoms. The purpose of the test and the need to collect the stool sample will be explained to you. 

You will be instructed not to eat any red meat for at least three days before the test. Tell your doctor if you are taking any medicine with or without prescription or any supplementation as some medicines can interfere with the results of this test. Bleeding cannot be detected in one stool sample; therefore, multiple stool samples should be collected on different days to increase the chances of obtaining accurate results.

You’ll be provided with a home kit to collect the sample. Follow all the information stated on the kit to avoid sample contamination. Several stool samples are collected at different days to get optimum results. After collection, the samples are tested in the laboratory. The procedure of collection varies for the two types of faecal occult blood test:

Immunochemical faecal occult blood test

• For this test, you will be provided with a container to collect the stool sample. Submit the sample to the lab as soon as you collect it. 

Guaiac-based test

• For this test, you’ll be provided with a test card with three sections for collecting stool samples on different days
• Smear the sample with the help of the application stick provided in the kit
• Once the sample is dry, return it to the doctor by mail or in person.

Normal results:

• The normal results of this test are written as negative. They mean that no blood was detected in the given stool sample.

Abnormal results:

Abnormal results are written as positive, indicating the presence of blood in the given stool sample. The following could be the possible meaning of abnormal values:

• Gastrointestinal tract cancer: colon, anus, rectum 
• IBD: ulcerative colitis, Crohn’s disease
• Inflammation of the stomach lining (gastritis)
• Piles (swollen veins in the rectum)
• Peptic ulcer
• Hernia

If you get abnormal results in this test, your doctor will suggest further tests such as colonoscopy to find the affected area. 

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.