AI tools are helping hospitals bill patients for more severe diagnoses—even when actual care hasn't changed, reversing expectations that AI would cut healthcare costs.

What happened: A PwC report found that AI note-taking tools are documenting more granular details about patient diagnoses and complications, allowing hospitals to assign higher-severity billing codes to patients. One Blue Cross Blue Shield analysis showed the billing code for acute posthemorrhagic anemia in new mothers jumped from 4% to 12.3% of maternity admissions between 2022 and 2025, yet the number of blood transfusions barely increased. An audit found fewer than 20% of cases actually met clinical criteria for the diagnosis, and this rise in billing intensity added $22 million（約35億円） to maternity spending at the hospitals studied in three years.

Why it matters: AI is ranked by PwC as one of five potential drivers pushing healthcare costs up to 9% in 2027—matching this year's rate, the highest since 2010–11. Rather than trimming waste as AI is often pitched to do, hospitals appear to be using it to optimize billing in their favor, turning a technology meant for efficiency into a tool for higher charges even when the care itself remains unchanged.

What to watch: While AI is the report's top-ranked new cost pressure, older drivers like labor and supply costs still account for more of the overall increase. The report's authors note that AI tools could eventually push costs downward by automating hospital administrative work or catching diagnoses earlier—but so far, the primary impact has been upward pressure on patient bills.