Elective surgery's surprise medical bill risk

The study found that 20.5% of elective surgeries — procedures like hysterectomies and knee replacements — performed at in-network facilities and by in-network primary surgeons resulted in an out-of-network bill.

• These bills came from providers who patients usually have no hand in choosing, like surgical assistants, anesthesiologists and radiologists.

Details: These bills ranged, on average, from less than $100 to several thousand dollars, depending on the specialty and the procedure.

• The average potential balance bill was $2,011.
• The largest potential bills tended to be from surgical assistants and anesthesiologists, which also were the most frequent sources of out-of-network bills.
• The South and Northwest had particularly high rates of these bills.

Go deeper: We all pay for surprise emergency room bills