url changed in proxy_pass

[John Quaglieri]

I have nginx installed on port 80 and apache is installed on port 81. I 
proxy php to apache and have nginx handle all the static and image content.

On my config I have an if statment similar to this:

if (!-f $request_filename) {
                 break;
                 proxy_pass  http://domain.com:81;
             }

I've noticed that if this is used the url gets rewritten to 
http://domain.com:81/file

Is there a way to have it not add in :81 into the url?

Thanks

John Quaglieri