Background: Rectal bleeding is common in the community and in general practice, but few studies have examined the causes of rectal bleeding in patients presenting to general practitioners.
Objective: To determine the frequency of neoplastic conditions in patients with rectal bleeding presenting in general practice and to explain the associations between presenting symptoms and final diagnoses.
Methods: We conducted two studies, the first in 1989, the second in 1991, in which we invited Danish general practitioners to register 3-4 patients aged 40 and over presenting with rectal bleeding.
Results: In Study 1 among 208 patients aged 40 and over and presenting with a first episode of rectal bleeding, colorectal cancer and polyps were present in 15.4 and 7.7%, respectively. In Study 2 among 209 patients aged 40 and over and presenting with overt rectal bleeding, 156 reported a first bleeding episode or a change in their usual bleeding pattern, and in this group colorectal cancer and polyps were diagnosed in 14.1 and 11.5%, respectively. In the group with unchanged bleeding the cancer polyp prevalence was 6.7% (P < 0.05). The patients in both studies were followed through a yearly letter to the GP for at least 32 and 22 months, respectively.
Conclusions: A joint analysis of the two study populations showed that only age and change in bowel habit contributed to differentiating the cancer from the non-cancer patients.