Histopathological assessment of bleeding from polyps of the colon and rectum.

One hundred and twenty seven colorectal polyps were examined to assess histopathological evidence of recent and old haemorrhage to test the usefulness of faecal occult blood tests in detecting colorectal neoplasia, in particular premalignant adenomas. Evidence of haemorrhage was consistently found in adenomas but was rare in non-neoplastic polyps. Haemorrhage within adenomas was predominantly stromal and associated with dilated, congested vessels. Factors associated with more severe haemorrhage were size, pedunculation, and villous growth; the degree of epithelial dysplasia and the age and sex of the patient were not associated factors. Proximal polyps showed more old haemorrhage than rectal polyps, but there was no such difference for recent haemorrhage.