Hi Imanni
If they are checking his large intestine, they are probably trying to ensure he hasn't got a problem with his appendix ..if it is they will remove it.
If it's not, they know to look elsewhere, so to check this area is not a bad thing.
Please let us know any outcome, and keep us posted.
If you need to know more, please get back to us
Take care (the both of you)
Ginger