A retrospective analysis of 640 patients who underwent 681 colonoscopi
c examinations between March 1984 and April 1996 was undertaken, The m
ajor indications were rectal bleeding (32.8%), change in bowel habit (
24.7%), abdominal pain (20.1%), abnormal barium enema (9.8%) and iron
deficiency anaemia (4.8%). Total colonoscopy was performed in 79.3% of
cases, The colonoscopic finding was normal in 49.8% of patients, Most
of the lesions were benign, Polyps and carcinoma were found in 9.2% a
nd 7% of patients respectively. 91.3% of the lesions were located dist
al to the splenic flexure and of the remaining proximal lesions, polyp
s and carcinoma accounted for only 2.2%. Rectal bleeding produced the
highest diagnostic yield (70%) followed by iron deficiency anaemia (61
.3%), change in bowel habit (48.1%) and abnormal barium enema (47.6%),
Lower yields were found in patients with abdominal mass (33.3%), foll
ow up colonoscopy (28.6%) and abdominal pain (26.9%). However, the dia
gnostic yield of clinically significant pathology varied widely among
the different indications, Therefore, selection of patients for colono
scopy based on the diagnostic yield of each indication may not be prac
tical, Sigmoidoscopy is suggested as the first line of investigation f
or patients suspected to have colonic diseases, particularly where the
re is limited trained manpower and facility, Total colonoscopy should
be reserved for sigmoidoscopy negative patients with persistent sympto
ms and high risk cases for malignancy.