I to have had this question and wrote to ACOG and here is the response that I got copied and pasted. I have a hard time billing for something that was not done but I have saved the email for that reason. Hope this helps.
This is in response to your e-mail of May 30, 2008. You asked about coding for obstetric care when the physician was not present for the delivery. The answer depends on the relationship between the primary obstetrician and the other physician.
ACOG's coding committee has stated that if the physician misses the actual delivery, but is present to deliver the placenta and perform the episiotomy, then it is acceptable to report the global obstetric code. In the case you described, however, the other physician delivered the placenta. In this case, you should report the appropriate antepartum care only code (59425 or 59426) and the postpartum care only code 59430. Any postpartum services provided in the hospital should be reported using E/M codes.
If, however, the other physician has a covering agreement with your physician, then you might be able to report the global code. Attached is a document that describes coding in these circumstances.
Please let us know if we can be of further assistance.
ACOG Coding Staff
The American College of Obstetricians &
Gynecologists (ACOG)