L/D Triage coding question

I have a question about how a labor and delivery triage should be coded. The provider has coded it as a level 4 emergency department stay for false labor. Stay was under 8 hrs, was not seen by a doctor (but one was consulted over the phone), NST was performed and patient discharged. Dx code submitted was 661.93. Primary insurance carrier accepted claim and paid. Secondary insurance carrier denied and says Dx not appropriate for ER stay. Should the provider initially have billed it using 99212-15 instead of using ER coding?

L/D Triage coding question