I thought I answered your original questions in the original post since there was no additional question after my last response.
I am typing this in a hurry, so I hope my question reads clearly. I am new to surgical coding and my providers have communicated that they always have another provider standing by when they do deliveries (OB/GYN) but they don't document in their op note if that person is called in to help what...
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I am interpreting what you are asking here differently than your original post.
FIRST PARAGRAPH:
I am interpreting Dr. A does a CS independently and provides pre-post delivery care. Then, Dr. B who is not part of Dr. A's group, comes in and does a salpingectomy, along with assist Dr. C. I would have to wonder why Dr. A is not doing the salpingectomy. It probably takes Dr. B longer to scrub than for Dr. A to remove the tubes.
If my interpretation is correct,
Dr A bills 59510.
Dr. B - IF the salpingectomy is done for disease process, using 58700 is 100% accurate. IF the salpingectomy is done solely for sterilization, we then hit a snag. The correct code should be 58611. However, since it is an add on, the carrier may deny since Dr. B is not billing another base code. In absence of official guidance for this, I would recommend billing the 58611, being fully aware you will likely need to appeal the claim along with records and explanation that a different physician performed the CS.
Dr. C would bill the assist for however Dr. B is billing, so either 58700-80 if disease process or 58611-80 if sterilization.
Another way to interpret your question is Dr A does a global CS independently. Dr. A then also removes the tubes, along with Dr. B assisting.
In that scenario,
Dr. A bills 59510. Again, knowing whether the salpingectomy is for sterilization or disease process is key. If sterilization, Dr. A also bills 58611. If disease process, then 58700.
Dr. B bills the assist for either 58611-80 (if salpingectomy for sterilization) OR 58700-80 (if salpingectomy for disease process).
SECOND PARAGRAPH:
You are asking about using -80 vs -81. There are various scenarios where one or the other is correct. If the assist is present during the entire procedure, AND the code allows for an assist, then -80 would be correct. If the assist is only present for a short period, AND the code allows for an assist, that is a perfect example of -81. You would need to make a judgment call if for example, the assist is there for 75% of the procedure.
Here is an old, but good previous posting regarding 80 vs 81 providing a reference from CPT assistant.
You also seem to be asking about what documentation is required to bill any assist. CMS basically states the op note must indicate who the assist was, and what was performed by the assistant. If the primary surgeon needs an assist, and the documentation of this exists in the op note, then I would not question the medical necessity of this. The documentation in the op note stating an assistant was required and what they did establishes the medical necessity for me. I also wouldn't question why or why not a clinician prescribes medication for a patient with high cholesterol.
In terms of coding, if the code permits an assist, and the documentation is there, then that is what you code.
You only need to establish more definitive medical necessity for surgery codes that have an indicator requiring this. For those procedures, the op note should indicate why an assist was required. In your original post, you reference a note stating patient was hypotensive and hemorrhaging. That would clearly indicate a medical necessity for another surgeon to assist.
My summary:
For codes that do not permit an assist under any circumstances, even if one was present, you would not code for the assist.
For codes that do permit an assist, the op note must indicate it was needed, who it was and what they did. You would code for the assist.
For codes that sometimes permit an assist, if the op note must indicate why, who and what, code for the assist.
Just like with any service, if the documentation is insufficient, query the provider. If the ultimate outcome is lack of documentation, then you should not code the service.
If this does not answer what you are asking, please clarify your question(s). I hope this helps!