That is something the doctor who told you that should be held accountable for. May I recommend you call and ask to speak to the head of the hospital where the surgeon operated and tell them this situation? Or if you have documented evidence of what you were told, present it to the medical license board. We don't need doctors giving out false information to patients!
Also, I recommend you find yourself a new and competent gastroenterologist for dietary advice and regular follow up appointments.
I assume that you had a sigmoid colectomy for your diverticular disease. One can think of diverticulae as little hernias along the colon since they are where the lining (mucosa) pooches out through the muscle layer. Since stool is the most firm in the left side of the colon this is generally where the worst diverticulosis is found. People who have had a bout of diverticulitis have approximately a one in three chance of having another. After two bouts the odds double and after three, they exceed 75%. any bout can present as a colon perforation requiring emergency surgery and, in many cases, a temporary colostomy. For reasons that are explainable by the configuration of the longitudinal muscle of the colon, diverticulae are not found in the rectum. So the only way to bring the chance of recurrent diverticulitis down to zero is to perform an abdominal colectomy with ileoproctostomy. This removes all of the colon down to the rectum and attaches the small intestine to the rectum. This was traditionally done for familial polyposis and typically results in 5 or 6 stools daily. What has been a much better compromise has been to remove the sigmoid colon when this has been the focus of the diverticulitis. Although there is still a chance of future diverticulitis the chance is reduced by approximately 90%. it sounds like what your surgeon was saying was that, at that time, all of your diverticulae were in the area that was taken out. This does not mean that you can't develop more upstream however. I say that this is a good compromise because it gives a very substantial reduction in risk without a significant lifestyle change in stool frequency. It is unfortunate that you have gone on to have a recurrent bout of diverticulitis but about one in ten patients that had the surgery that you had will. I appreciate the vigilante advice above but it is misdirected. The procedure that you underwent is the standard one that I would have recommended.
I was not objecting to the choice of procedure, but at the patient being told she would not get diverticulitis anymore after the operation.
She did get diverticulitis again after the operation and you outlined above chances of recurrence. The surgeon, if indeed they made the blanket statement the patient asserts, was wrong to have done so, in my opinion. Ninety percent reduction in chance of getting it again does not equate one hundred percent.