Catheter is for stoma of the K/BRIC type pouch. The catheter is inserted into the stoma in order to eliminate. these types of pouches are internal capture, in contrast to an exterior bag/appliance that goes over a stoma. One would consider both types of stomas as an ostomy.
The first post in this thread refers to using a catheter with a J pouch. It would be best to get clarification from Ellie85. It sounds like they’re using the catheter to eliminate from the anus.
If you have a J pouch, then you probably don’t need to worry about this. I’m sure you’ve got enough other things to worry about! hope this helps. Stay well, Jan