Note: I've spent on the order of 30 hours on the phone over the past couple months trying to get things sorted out between my doctor, my insurance, and the provider of the drug that I need for my vision. The folks at the insurance can't always help, but they've always been willing to discuss things and see what they _can_ do.
What should have happened is that they should do the ultrasound right there, on the spot. But, the dr's office can't do ultrasounds. That has to go to the imaging department, which had to be scheduled 4 weeks out. Sigh... I won't keep going, but this whole situation is stupid and engineered to extract as much money as possible.
The next time something like this comes up, if you're feeling up to it, try pushing back. If you have the time to throw at it, the worst outcome of trying is usually just staying where you started.
At the end of my many hours on multiple phone calls getting everyone to agree to pay for treatment I need... the company in charge of making it called to let me know they've been retasked to making COVID vaccine and won't be making the drug I need for at least 3 months. So no treatment for at least that long. So that's fun.
I work close enough to healthcare that I can say that while insurers do take cost of treatment into account they are looking to minimize ongoing treatment costs - if there is a 5$ pill and a 500$ pill available for treatment the insurer may prefer to trial you initially on the 5$ pill if it's been proven effective for a good proportion of patients, but they do use calculations to minimize those ongoing costs that includes costs from condition escalation (i.e. if you have a boil you're absolutely going to get antibiotics covered since dealing with a septic boil is an emergency room visit.