Digestive EndoscopyEndoscopic findings in the upper gastrointestinal tract of faecal occult blood-positive, colonoscopy-negative patients
Introduction
Detection of faecal occult blood (FOB) by means of guaiac-based tests, followed by colonoscopy, is recommended for colorectal cancer screening in average risk populations [1]. However, approximately 60% of screened subjects do not have any cause found in the colon to account for the occult blood loss [2], [3]. There is no general consensus regarding the further management of these ‘FOB-positive, colonoscopy-negative’ individuals. Whilst false-positive FOBs may arise due to the peroxidase activity of ingested foods [4], it has also been demonstrated that small amounts of blood loss from the upper gastrointestinal tract (UGIT) can be detected by guaiac-based FOB tests [5]. Some previous studies have suggested that there is a high prevalence of UGIT pathology, including cancer, in FOB-positive, colonoscopy-negative individuals [6], [7], [8], [9]. However, as the upper gastrointestinal endoscopy (UGIE) was performed at variable or unspecified times after the colonoscopy in these studies, it is possible that the UGIT pathology may have changed in the time between the two endoscopic procedures. Same-day UGIE and colonoscopy, referred to as ‘bi-directional endoscopy’, would overcome this problem. We have reviewed our own experience of bi-directional endoscopy in order to determine the prevalence of UGIT pathology in FOB-positive, colonoscopy-negative patients.
Section snippets
Methods
A retrospective audit was conducted of all patients who underwent same-day UGIE and colonoscopy in the endoscopy unit at our institution between January 2000 and December 2001. Patients were identified from the endoscopy record books; case notes and endoscopy reports were retrieved for data extraction. Information was collected on FOB status, blood haemoglobin level, symptoms, medication (aspirin, non-steroidal anti-inflammatory drugs [NSAIDs], anticoagulants) and the endoscopic findings. The
Results
A total of 292 patients were identified who underwent bi-directional endoscopy during the 2-year study period. Of these, 193 patients were excluded: 94 – FOB status not recorded, 59 – negative FOB test, 28 – incomplete colonoscopy, 12 – acute gastrointestinal haemorrhage or known pathology to account for a positive FOB. The demographic details, including primary indications for colonoscopy, of the remaining 99 patients are shown in Table 1.
The colonoscopy findings are shown in Table 2. The
Discussion
The management of FOB-positive, colonoscopy-negative individuals poses a clinical dilemma; it is uncertain how extensively these subjects should be investigated in order to identify a cause for the occult blood loss. We found that approximately two-thirds of our FOB-positive patients had no colonic source of blood loss identified, a similar proportion to that reported from previous studies [2], [3]. Endoscopic examination of the UGIT revealed significant pathology in approximately one-third of
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