Spanish to English Medical Insurance Medical Invoice

I have 2 medical invoices from Argentina. One is for laboratory tests and the other for emergency room treatment. For both, the charges are split into "honorarios" and "derechos" on each line of the invoice. For the lab tests, the "derechos" are greater than the "honorarios". For the emergency room treatment, the "honorarios" are zero and amounts are only entered for "derechos". Unfortunately, there is no further context. Normally I wouls expect "honorarios" (rather than "derechos") to indicate "medical fees", but Im not sure in this case. Can anyone help with the meaning of "derechos" in this context? Thanks, John