What is considered the most serious,risky surgery?

It's not the surgery, it's the surgeon. AND the anesthesiologist.

it must be compared to other elective procedures. Bypass is actually pretty safe. The bariatric surgery team at my hospital has never had a perioprative fatality.

I would think anything puncturing the dura mater would be toward the top of the list.

But my opinion? Anything that is done strictly for cosmetic reasons. I don't mean repair of something that's damaged or illformed -- the guy with the "tree root" foot could get around, but it's not a healthy foot. I mean getting your roman nose turned more "pert" or getting bigger boobs -- that sort of thing. I'm not going to let anyone expose me to clots, MRSA, sepsis, adhesions, "whoops, where's the sponge? miss counts" etc., unless my life would be endangered if I didn't.

I've seen people die from something as simple as repairing an umbilical hernia -- no entrapment, the lady just didn't like having an "outie" after she had a child, the surgeon went in to do the repair, nicked the bowel, and she died. For a cute bellybutton.

The obesity is quite a comorbidity. Some end up having respiratory issues. Healing can be a concern based on diet. Anastamotic leaks are awful as well, not to mention bleeding. Our bariatric surgeons are also very good, we've seen less complications over the years, but the patients being the type they are set them up for more issues.