Every day, patients across America crack open envelopes with bad news. Yet another health insurer has decided not to pay for a treatment that their doctor has recommended. Sometimes it’s a no for an MRI for a high school wrestler with a strained back. Sometimes for a cancer procedure that will help a grandmother with a throat tumor. Sometimes for a heart scan for a truck driver feeling short of breath.

But the insurance companies don’t always make these decisions. Instead, they often outsource medical reviews to a largely hidden industry that makes money by turning down doctors’ requests for payments, known as prior authorizations. Call it the denials for dollars business.