"Investigator assessment of rectal and sigmoid mucosa up to 40 cm from anal verge" -- okay, that's nearly 16 inches.

It's not hard to understand why someone might want to refuse the end-of-trial sigmoidoscopy, as I think one or two patients did. After feeling much better, the ones who honored their agreement to have the endpoint test were very brave. They might have been taking a chance on having their disease flare up again, with the aggravation from the instrument.