The use of faecal haemoglobin in deciding which patients presenting to primary care require further investigation (and how quickly) – the FIT approach

Patients presenting to general practitioners (GPs) with new bowel symptoms can be difficult to assess since symptoms are poor predictors of pathology. National Institute for Health and Care Excellence referral guidelines highlight features that may suggest colorectal cancer (CRC) including rectal bleeding, palpable mass, iron deficiency anaemia, but also non-specific symptoms such as weight loss. In those patients referred for investigation on the basis of symptoms alone the yield of CRC is low (2-3%). Faecal immunochemical tests (FIT) quantify faecal haemoglobin (f-Hb) and are widely used in bowel screening programmes. A number of groups have now studied the utility of FIT in patients attending primary care with new bowel symptoms. Studies have concluded that if the FIT is negative and clinical assessment and full blood count normal then the risk of underlying significant bowel disease (SBD) is extremely small. Furthermore, patients with f-Hb ≥400 μgHb/g faeces have >50% risk of SBD and should be investigated urgently. Thus, a single f-Hb requested by GPs provides both a reliable prediction of the absence of SBD, and an objective assessment of the need and urgency of further investigation.