BCBS Denying Inpatient After Appendectomy, Help Requested

tl;dr Received notice from BCBS that they did not approve my inpatient stay as it did not appear to be medically necessary. Need advice on what documentation to submit to appeal.

I recently needed to have an appendectomy after being in pain for more than a few months. We’re likely looking at a diagnosis of chronic appendicitis, as the pain has totally resolved.

I went into the ER and was taken up to surgery hours later. I remember that after surgery I was wheeled into a shared room for recovery. Upon waking up, I had horrible nausea – I could barely speak or look at my phone, refused to eat, etc. There is not a lot I remember from that first day as I was always in-between IV pain meds or a ton of IV anti-nausea medications. I remember that they initially wanted me to go home that night, but after I worsened (described below), that was never discussed again. They had me on IV fluids (Lactated Ringers) all day, and they kept me overnight.

I was able to pee once after surgery, but then stopped being able to. I would try and nothing would happen. Sometime in the early morning of the second day they had to place a catheter. A few hours later they did a blood test and my hemoglobin and RBC were concerningly low. My stomach felt like it was on fire. Later that afternoon, I had been able to eat a little and another blood test showed improvement. My nausea also subsided and I was finally able to pee on my own. We got the pain under control. I was discharged that day.

I am concerned about what I can submit to appeal the stay not being approved. There’s no possible way I could have been sent home provided my symptoms (above). To be frank, that was not an option given to me. I can see bits and pieces of this recollected in the nurses notes from the stay, and I can see the repeated orders for all of the nausea medication (Ondansetron and Prochlorperazine). I would appreciate any guidance folks may have on what I ought to try to submit in response to the denial.