The Faecal Occult Blood Test (FOBT) is a diagnostic tool that plays a significant role in the detection and diagnosis of gastrointestinal disorders. This test, which is non-invasive and relatively simple to perform, is designed to detect hidden, or ‘occult’, blood in the stool. The presence of occult blood can be an early indicator of several gastrointestinal conditions, including colorectal cancer, gastric ulcers, diverticulosis, and inflammatory bowel disease.
The Faecal Occult Blood Test is often used as a screening tool for colorectal cancer, one of the most common types of cancer worldwide. Colorectal cancer often begins as small, noncancerous clumps of cells called polyps. Over time, these polyps can become cancerous. Detecting these polyps early through regular screening can significantly reduce the risk of developing colorectal cancer.
The FOBT works by detecting tiny amounts of blood in the stool that may not be visible to the naked eye. This blood can originate from anywhere in the digestive tract, from the mouth to the anus. The test involves collecting small samples from different parts of the stool on three separate occasions. These samples are then analysed in a laboratory for traces of blood.
There are two main types of FOBT: guaiac-based FOBT (gFOBT) and immunochemical FOBT (iFOBT or FIT). The gFOBT uses a chemical reaction to detect the presence of blood, while the iFOBT uses antibodies to detect human haemoglobin protein in the stool. Both tests are effective at detecting occult blood; however, iFOBT is considered more sensitive and specific for detecting lower gastrointestinal bleeding.
It’s important to note that a positive FOBT result does not necessarily mean that a person has cancer or another serious gastrointestinal disorder. Other conditions such as haemorrhoids, anal fissures, or certain medications and foods can also cause blood in the stool. Therefore, a positive FOBT result is usually followed by further diagnostic tests, such as a colonoscopy or sigmoidoscopy, to determine the source of the bleeding.
Despite its effectiveness, the FOBT has some limitations. It may not always detect blood in the stool, especially if bleeding is intermittent or if the blood is coming from higher up in the digestive tract. Furthermore, it cannot distinguish between blood from different sources within the gastrointestinal tract. Therefore, while it is a valuable tool for initial screening, it should not be used as a standalone diagnostic test.
In conclusion, the Faecal Occult Blood Test plays a crucial role in the early detection and diagnosis of various gastrointestinal disorders. It serves as an effective screening tool for colorectal cancer and can help identify other conditions that cause bleeding in the digestive tract. However, like all diagnostic tests, it should be used in conjunction with other tests and clinical information to ensure accurate diagnosis and appropriate treatment.