When Kristy Uddin, 49, went in for her annual mammogram in Washington state last year, she assumed she would not incur a bill because the test is one of the many preventive measures guaranteed to be free to patients under the 2010 Affordable Care Act. The ACA's provision made medical and economic sense, encouraging Americans to use screening tools that could nip medical problems in the bud and keep patients healthy.

So when a bill for $236 arrived, Uddin — an occupational therapist familiar with the health care industry's workings — complained to her insurer and the hospital. She even requested an independent review.

"I'm like, 'Tell me why am I getting this bill?'" Uddin recalled in an interview. The unsatisfying explanation: The mammogram itself was covered, per the ACA's rules, but the fee for the equipment and the facility was not.