The fecal immunochemical test (FIT) is a diagnostic technique that examines stool samples for traces of non-visible blood, which could potentially indicate conditions including

bowel cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel ...

. Symptoms which could be caused by bowel cancer and suggest a FIT include a change in bowel habit,

anaemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availab ...

, unexplained weight loss, and

abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Since the abdomen contains most of the body's vital organs, it can be an indicator of a wide variety of diseases. Given th ...

. By using a

random forest Random forests or random decision forests is an ensemble learning method for statistical classification, classification, regression analysis, regression and other tasks that works by creating a multitude of decision tree learning, decision trees ...

classification model, sensitivity can be increased. Blood in stools does not always mean the presence of bowel or

anal cancer Anal cancer is a cancer which arises from the anus, the distal opening of the gastrointestinal tract. Symptoms may include bleeding from the anus or a lump near the anus. Other symptoms may include pain, itchiness, or discharge from the anus. A ...

, it could be from other bowel diseases such as

ulcerative colitis Ulcerative colitis (UC) is one of the two types of inflammatory bowel disease (IBD), with the other type being Crohn's disease. It is a long-term condition that results in inflammation and ulcers of the colon and rectum. The primary sympto ...

Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the ...

or even

hemorrhoids Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''he ...

. A 2022 UK guideline for patients with signs or symptoms of suspected colorectal cancer recommends the use of a FIT threshold of faecal

haemoglobin Hemoglobin (haemoglobin, Hb or Hgb) is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobi ...

≥10 μg Hb/g to select patients with symptoms for an urgent referral for colorectal cancer investigation.

References

Medical tests Stool tests {{med-diagnostic-stub