Hospitals and other healthcare providers are different from other businesses in the way they show the people who use their services (patients) a lot of individual detail.
Each service that a hospital does is billed separately, at a fixed amount. So, a patient might come in for a series of tests. The tests are all itemized separately and the bill shows the charges associated with each test. For example, a visit to the emergency room might result in a bill like:
Emergency room charge $400
Lab test $100
Chest X-Ray $200
The patient will then receive a total bill of $700 in billed charges, which the hospital recognizes as gross revenue.