The pouchogram is not painful. All they do is fill your pouch with contrast and take a series of xrays to check for leaks. Sometimes the contrast can flow upwards into the bag and cause a bag leak. They are only telling you to bring extra supplies in the event that you have a leak. Be thankful, most technicians do not tell us this! There are private restrooms near the xray rooms so should you need to change your bag you will have space and time to do it.
Sue