check constraints

I have little experience with postgres' check constraint features and was hoping to get some guidance. We have a table which houses links to various user files. The PK of this table is fi_pk. There are several tables in which a foreign key (fi_fk) to this field exist. We are implementing a feature which will allow users to remove old files from their repositories. It would be nice to have a check that goes out to all tables that have this fi_fk field and checks to see if the fi_pk for their particular record exists and would then not allow the deletion if a link occurs somewhere.
I realize that I can do this with specific SQL in the code but was wondering if it's possible to implement a sort of general database wide check of this nature. That way if future tables are added with this FK field then the code would not have to be altered.
Thanks.
Jodi Kanter