I can't count the number of times I've heard a patient say: "I didn't receive my lab results, and 'no news' is 'good news' so they must have been normal." Wrong. There are so many steps between ordering the labs and getting the results to you that results can go missing and important health information can be lost.
I became aware of this initially at my first job out of residency: I was covering for a colleague while he was out of town. I reviewed his patient's chart before seeing him and noticed that a skin cancer had been removed 6 months before. I walked in to see the patient for an unrelated problem, and, when examining him, I asked to see where his skin cancer was. He said, "I have skin cancer?" He had no idea since my colleague, for whatever reason, hadn't notified him. Because of this, I started a new process of notifying all of my patients of their results by mail. It was time intensive to print out all of these letters (usually every weekend), but I wanted to ensure that patients always received their lab results. I instructed them when ordering their labs (or procedure) that no news was NOT good news, and that they should call me for results if they hadn't heard anything in two weeks.