There are several alternatives available to a flexible sigmoidoscopy. These will vary slightly depending on your situation and you may have already had some of them done.

The tests usually start from the simplest, such as

a rectal exam done with the doctor's finger

testing stool for blood

abdominal x-ray

barium enema x-ray

blood work

and proceed to more complicated tests, like

Cat Scan, CT or MRI

Colonoscopy

If you have questions about your particular situation, you should discuss the different alternatives with your doctor and decide which one, if any, is appropriate for you.