Hospitals are organization with the highest information density. This means that information is highly wrapped-up in the business process, or what is about the same: the business is organized by computers or information systems.
This is the example.
In a traditional hospital the patient will be cured and consecutively be cared for a while before he gets fired. To do this a doctor or medical specialist will have to visit the patient, check whether all is ok and authorize him to leave.
In an information-dense hospital this procedure is more or less the same, but there is one difference and this is make clear by answering the question: when does the patient leave? When the doctor has visited him or when he is cured.
This seems like the chicken-or-egg problem, but there is indeed a difference.
A information system may control the time the patient has spend at the hospital and may program a planning for doctors to visit patients that are likely to have cured. In this case, the process is optimized by the client (patient) needs and not by the availability of the specialist.
As said this is only one example. The uniqueness of the hospital complexity is not so much the different kinds of specializations that are required to cure patients, but the interaction between these specialists and between computer systems and medical equipment.
Information systems in hospitals are more complex than other information systems and require a special training or degree to build them. Yet the types of information systems that are required in a hospital are no different than systems in normal organizations. There are a few categories and the integration between them is the biggest challenge.