The misuse of the faecal occult blood test under the lower gastrointestinal two week wait rule

To find the proportion of patients with a faecal occult blood (FOB) performed as part of the referral for the lower gastrointestinal two week wait (2WW) referral system, and whether this correlates with the cancer status.

All patients referred to the colorectal cancer service using the 2WW referral criteria, between August 2005 and August 2007, were identified using the hospital's cancer audit database. Faecal occult bloods and cancer status were recorded for each patient.

Two thousand one hundred and fifty-nine patients (1177 female: 903 male; median age 58; age range 18-98) were referred by general practitioners. The FOBT was only performed on three samples in all cases. In total, 172 of 2159 patients (7.9%) had an FOB performed prior to their referral, with 55 of 172 patients (31.9%) as part of the referral for 2WW. Sixteen of 172 patients (9.3%) had an FOB performed in the presence of overt rectal bleeding. In only 2 of 172 patients (1.1%) the FOB correlated with a colorectal cancer. Unnecessary testing for FOB costs has cost pound4072.96 in total.

A significant number of faecal occult bloods are being performed and the detection rate, even in this symptomatic group of patients, is very low. It is evident that the test is being performed in the community on three samples and not six. This, combined with the high false positive rate, leads to patients not only undergoing unnecessary psycho-social consequences but could potentially lead to significant risks from unnecessary invasive investigation as well as the added financial burden of test itself.