By all accounts it does not show up on a credit report. But like Bill said, I suspect that when you sign that mortgage paperwork, you are affirming that all of your outstanding debts have been disclosed.
When we refinanced our home this year, we had to supple 90 days of bank statements. So, if you are financing your purchase it will show up on those bank statements when it goes to an underwriter.
Borrowers are required to disclose all debt. If you read the loan application (form 1003) you will see that it is considered loan fraud if you fail to disclose.