You may have signed away any possibility of damages when you signed the release prior to the procedure. I cqan't remember what it said word-for-word, but it seems to me like one of the possible complications included bleeding. The doctor also verbally went over this with me.
The bleeding sometimes cannot be predicted. Cautery might well have been performed and your straining on the commode may have caused it to open up.
Go ahead with a lawsuit if you wish, but it sounds like an uphill battle to me.
Well, so much for tort reform from conservatives, considering the comments on this thread.