Summary
Three hundred and thirty patients having had previous colonoscopic polypectomy of
adenomas were recalled for follow-up and submitted to all available diagnostic methods:
occult blood testing, digital examination, rigid proctosigmoidoscopy, fibre-optic
sigmoidoscopy, total colonoscopy and double contrast barium enema. Polyps up to 7 mm
diameter were electtro-coagulated during diagnostic endoscopy but larger polyps were
left in situ for barium enema before polypectomy at a later date. Disparities between
endoscopy and X-ray were rechecked by one or both procedures.
Occult blood testing, digital examination and rigid proctosigmoidoscopy were found
to be inaccurate or ineffective in diagnosis of the 37 % of patients with further
adenomas or carcinomas. Double contrast barium enema demonstrated 71 % of larger lesions
compared to the 92 % shown by colonoscopy. The commonest sites of X-ray inaccuracy
were in the sigmoid colon and caecum. Colonoscopy permits immediate electrocoagulation
or snare polypectomy of any lesions seen, as well as being the more accurate investigation
and is, therefore, the procedure of choice in post polypectomy follow-up.
The mean time taken for diagnostic total colonoscopy in this series was 15.3 minutes,
comparable to the time taken for barium enema. Postal questionnaire showed both procedures
to be equally well tolerated by the patients. Thirty per cent of colonoscopies were,
however, considered technically difficult by the endoscopist, and for these patients
it is suggested that follow-up should be by the combination of fibre-sigmoidoscopy
using carbon dioxide insufflation and immediate double contrast barium enema. Should
this combination indicate a need for total colonoscopy, then almost all adenomas and
cancers would be detected. Total examination of the colon by one or other means is
essential, over half the patients with adenomas and three of the five patients with
carcinoma showing no pathology in the territory of fibresigmoidoscopy or limited colonoscopy.
Key words:
Colonoscopic polypectomy - Double contrast enema - Follow-up - Polyp detection
