When searching for tests, note that if the "Common" box at left is checked, as shown below, you will only see a limited list of common tests. If you uncheck the box, this will (after a short delay) reveal all of the available tests.
Another way of searching for a test is by section, which reveals the major groups of tests, as shown below.
A third way is to search by category, which is quicker if you know which laboratory/imaging service performs the type of test you are looking for.
If you know the name of the test, you can simply type part of the name, or the common abbreviation, into the "Name" search box at right.