Investigations

The preferred investigations for rectal carcinoma are:

• full blood count
• blood film: test for iron-deficiency anaemia
• rectal examination: palpable mass in less than 50% of cases
• rigid sigmoidoscopy and proctoscopy: performed at the initial consultation - reveals tumours in sigmoid region and enables positive evidence by biopsy to be obtained
• flexible sigmoidoscopy
• stool sample: test for occult blood
• colonoscopy: enables inspection and biopsy of the higher reaches of the colon. Gives high sensitivity if used by an experienced operator. Requires a full bowel preparation.
• barium enema: usually reveals the tumour as a stricture or filling defect. But negative results are not uncommon, so if this occurs when the condition is suspected, repeat the investigations after a few weeks.
• IVU: a useful preoperative investigation if there is a risk of ureteric involvement.

A barium enema and other invasive tests can be particularly distressing and should not be undertaken lightly.