The Prometheus test for IBD looks at the levels of several different antibodies in your bloodstream, antibodies that are specific to Crohn's or UC. It's not a genetic test.
Prometheus does have another test, this one is genetic, that tests for a person's ability to metabolize Imuran or 6-MP. This test is called the TPMT Genotype.
The pediatrician probably ordered the first, or possibly just ordered tests for ESR and CRP, two tests that look for inflammation markers.