In 2015, a college student in Texas named Elizabeth Moreno had back surgery to correct a painful spinal abnormality. The procedure was a success, and her surgeon followed it with just a short-term prescription for the opioid pain-killer hydrocodone to ease a speedy recovery. Then came a “routine” urine drug test, ostensibly to ensure she didn’t abuse the powerful drug.

A year later, she got the bill for that test. It was $17,850.

She understandably didn’t see it coming, according to report on her case in Kaiser Health News. The surgery was covered by her insurance and she had weaned herself off the painkiller with no problems. When the surgeon’s office asked for the urine test in mid-January 2016: “I didn’t think anything of it,” Moreno told KHN. “I said fine, whatever.”