According to a flyer from a Los Angeles chiropractor:

Live Blood Analysis is a simple procedure for obtaining a quick and accurate assessment of your blood.

With only a sample, taken virtually without pain from your finger, [the test] is able to provide a composite of over 25 aspects from your live blood.

Darkfield microscopy now allows us to observe multiple vitamin and mineral deficiencies, toxicity, tendencies toward allergic reaction, excess fat circulation, liver weakness and arteriosclerosis.