I've had both a flexible (that was straightforward) and rigid (a disaster). The flexible cysto was to check for a bladder tumour following blood in urine. It was done at outpatients under local anaesthetic. Helped that I could see on a screen the probe revealing inside of my bladder! Consultant could find no trace of a tumour.
Unfortunately an MRI scan subsequently 'revealed' a tumour 30x38mm, so decision was taken to do a rigid cysto.
Rigid was was under general anaesthetic. This also failed to find a tumour but the invasive procedure left me with urinary incontinence that was considerably worse than it had been immediately beforehand. Prior to the procedure I leaked c.20ml/day (itself the fall-out from a prostatectomy and external beam radiotherapy ten years earlier). But from the moment I stepped out of the hospital following the rigid cysto three years ago to this very day my leakage has been consistently ten times worse, anything up to 600ml or more a day.
At first the consultant insisted there was no way the cycstoscopy could have triggered the problem, but eventually he accepted the possibility the procedure might have disturbed tissues previously damaged by the RP and EBRT I'd had ten years prior.
A friend has since told me her urologist warned her that a rigid cystoscopy was akin to the rape of the bladder! I have also read that rigid cystos are statistically more likely than flexibles to lead to complications, paerhaps because a flexible will be for less serious conditions but the suggestion was also made that when the patient is under general anaesthetic the surgeon is under less scrutiny.
Make of that what you will!