Information has many ways of falling through the cracks in hospitals and medical practices.
The wrong test may be mistakenly ordered by the doctor. The ward secretary may order the wrong test. The lab may perform the wrong test, or rarely perform it on the wrong person. The result may not be available until after the patient leaves the hospital, and then gets lost in cyberspace; or it reaches the chart after the doctor has dictated the discharge summary and is never seen.
Usually more than one doctor takes care of each patient, but each may not be aware of everything the other has done, or which tests were ordered and are still pending.
A simple fix would be to require that all electronic medical records systems must be linked to the laboratory and radiology departments, and must be able to generate a list of all tests ordered; their results; and those tests whose results are still pending. At the end of a hospitalization, each doctor would have to sign off on the list, to ensure all tests had been considered.
We currently have a hodge-podge of hundreds of proprietary EMR systems that do not communicate with each other throughout the US, and the system I use does not have this capability.
Electronic medical records are a wonderful idea in theory. In practice, they are fraught with difficulties and potentially may be accessed or "hacked" by unauthorized individuals, making a mockery of patient confidentiality. The problem of confidentiality is central to getting a working EMR system in place throughout the nation, through which doctors and patients can communicate; yet it requires cybersecurity resources beyond the financial resources of hospitals and medical practices in the private sector. This is why the development and maintenance of such a system must be federalized.