Usually a complication called sepsis which is due to organ failure. Pretty rare to happen after minor surgery, but possible. I'm sure there are other reasons as well.
please tell me what can cause a heathy person to go into a coma after tonsil operation? jk
Was the coma induced by Doctors as sedation to be put onto life support? or was the coma caused by the surgery?
David, so sorry to hear of you wife's problems. Unfortunately, we are not doctors here so we can't really give you medical advice, just some possibilities to ask your doctor about. You can try posting on the expert forum, they are doctors and may be able to help.
Having said that, she may have developed sepsis, or basically an increased level of toxins in her blood due to infection or some other cause. It is too common especially with surgery on the digestive system. You should ask your doctor about that, there are things they can do to reverse it.
Good luck to you and your wife, I hope this helps. Perhaps it's a place to start.
Jon