The endoscopically normal colon: when is mapping biopsy histopathologically justifiable?

OBJECTIVE: Mapping biopsy of endoscopically normal colon is a contentious area and generates considerable work for histopathology services. Managing demand for pathological testing is a current healthcare priority. In this retrospective audit, the authors aimed to establish diagnostic yield of mapping biopsy in this specific subgroup and identify situations where practice could be safely streamlined.
DESIGN: Cases were retrieved over a 10-month period. Histopathology results were correlated with relevant endoscopy reports. The data were anonymised and analysed.
SETTING: Department of Cellular Pathology, Southampton General Hospital, UK.
RESULTS: 717 cases were retrieved. 308 (43%) cases were reported as endoscopically normal. 278 (90%) cases with endoscopically normal/near normal mucosa showed normal/near normal histology. 30/308 (9.7%) endoscopically normal cases showed pathological abnormalities. 9/308 (2.9%) cases of microscopic colitis were detected. Of the 30 cases with pathological abnormalities, 20 (66.7%) presented with change in bowel habit and 6 (20%) had a pre-existing diagnosis of inflammatory bowel disease.
CONCLUSIONS: Pathological abnormalities in endoscopically normal colon are found most frequently in those who present with change in bowel habit or a known history of inflammatory bowel disease. The authors support biopsy in these individuals and believe that mapping biopsy of endoscopically normal colon in patients referred for other reasons (eg, bright red rectal bleeding or iron deficiency anaemia) should not be performed routinely as diagnostic yields are very low. Guidelines on appropriate use of mapping biopsy in this setting are limited. Streamlining patients based on reason for referral or presenting symptoms may be a useful step towards more effective management of histopathological demand.