Some information obtained from American Academy of Pediatrics: 99464 cannot be reported with 99465; physical presence of the provider has to be requested by the delivering MD AND have a newborn who may require immediate intervention; medical records must include request for attendance; any medically necessary procedures provided in delivery room may be reported separately; may be reported with 99460, 99221-99223, 99477, 99468, 99291-99292; oxygen and CPAP are included with 99464; CANNOT be used if presence of the provider is a hospital mandate; cannot be billed with 99360.
I hope this helps some with additional information available about the code. I could look further into particular denials if you provide some more information. What codes was it billed with, what state are you in and what insurance carrier(s) is it?