The upper endoscopy examination is limited after the duodenal switch operation to the first part of the three parts of the Duodenum. So the ampulla of vater can not be examined. This is also why an ERCP cannot be performed in patients after the duodenal switch operation.

Lower Endoscopy (Colonoscopy)

Duodenal switch operation does not change the anatomy of the large intestine. The colonoscopy examination can be done as with a patient who has not had the duodenal switch operation. The only consideration should be the bowel preparation. It has been noted that the patients after the duodenal switch operation require a longer than usual time for the bower prep. We recommend patients going on a liquid diet for 4-5 days before the planned procedure. I know it sounds unexpected that we recommend patients after the duodenal switch to be on liquid diet. You may also want the physician doing the colonoscopy be aware that you may need more aggressive and longer bowel prep.

Please see examples of the upper endoscopy here.