And if you find any issues, you test the whole shipment.
And then you compare the results to the outgoing QA test results.
And if any results can't be explained by failures relating to shipping, then you fire your supplier.
You let them know ahead of time that this is the procedure you'll apply, and then they'll do proper QA testing.
You should probably run with multiple suppliers in the first place, so it's easier to switch between them? Of course, that extra overhead probably will eat into your cost savings.
No major medical company wants to risk recalling defective product by using a disreputable Chinese manufacturer. Unknowingly selling counterfeit product is a pretty bad look to the FDA and consumers.
This is the main reason why many procurement departments have a no China policy.