the doctors order the antepartum rhig based on the patients blood type that comes with our regular prenatal work-up.
for post partum, OB calls the lab with information on every new birth they have, which includes baby's name, time of birth, mom's name, mom's DOB and blood type. All Rh negative moms gets a blood draw w/in 2 hrs post-delivery for possible rhogam work-up after we get cord blood samples to be tested for ABO/Rh and DAT.
It's the labs responsibility to order a post-partum rhogam work-up if the baby's blood type is positive.