FIT Information for Patients


Why has my doctor requested a faecal immunochemical test (FIT)?

The symptoms of a wide range of gastroenterological (digestive system) disorders are very common and often overlap. Thus, differentiating between patients with serious bowel disease, from those with benign functional or diet related conditions, such as Irritable Bowel Syndrome (IBS), and minor colorectal disease such as haemorrhoids, hyperplastic polyps and simple diverticular disease, can be very challenging.

Doctors may therefore request the simple non-invasive FIT as a first step for patients presenting in with lower abdominal symptoms.

Understanding FIT – Looking for microscopic traces of blood in the poo

In a healthy bowel, there should be no reason for blood to appear in the poo. With some bowel conditions however, lesions can appear in the lining of the bowel, and these lesions can allow the passage of blood into the bowel. As digested matter is passed through the bowel, it may come in contact with the lesion(s), and this can result in blood being transferred to the digested matter.

FIT looks for microscopic traces of blood in the poo, which may indicate if there is damage to the lining of the bowel. The FIT will not specify where in the bowel the bleeding has come from, or the nature of the affected area, but it will indicate to the clinician that there is a pathology in need of further investigation.

You may be referred for a FIT if you:

  • Have unexplained abdominal symptoms
  • Experience a change in bowel habit lasting longer than 3 weeks
  • Have unexplained weight loss
  • Have pain or lump in the stomach area or back passage
  • Are enrolled in a national screening programme

Previously, most people with one or more of the above conditions would be referred for an endoscopy. These procedures are unpleasant and not without risk, they are also costly for the NHS and patients may be subject to long waiting lists. FIT is a fast, non-invasive and cost-effective method to help triage patients and determine the appropriate patient pathway for further investigation to diagnose the problem.

Find out more about symptoms from Bowel Cancer UK

Faecal Haemoglobin Levels

The presence of haemoglobin (blood) in the poo could be indicative of a number of conditions, ranging from non-threatening conditions (such as haemorrhoids) to functional disorders and genetic conditions, to significant colorectal disease (including cancer). The purpose of faecal immunochemical testing (FIT) is to identify how much blood is present in the poo sample, allowing the clinician to investigate and treat patients according to their symptoms.

After your test, your doctor will contact you to discuss your results, and advise on the next steps. Your FIT result depends on a multitude of factors, including:

  • Age
  • Sex
  • Lifestyle risk factors
  • Genetic risk factors
  • Other gastro-intestinal conditions
  • Iron deficiency anaemia

PLEASE NOTE: The information on this site is primarily designed for use by healthcare professionals rather than the general public. Similarly the products are not suitable for personal purchase.  If you have any concerns about Faecal Immunochemical Testing and related conditions, please speak to your GP.