The diagnostic principles and practices of Oriental medicine rely heavliy upon detailed questioning, observation, and palpation, but utilize modern laboratory testing and diagnostic imaging when needed.

Classical Oriental Medicine Assessment
The diagnostic procedures used in TOM includes questioning (medical history, lifestyle), observing (posture, facial color, skin, tongue, etc), listening (breathing sounds), smelling (breath, body odors, urine) and palpation (touching, pressing, and pulse-taking). Six or more pulse aspects correlating with body organs/functions are checked on each wrist to determine which organs are deficient or excess in yin, yang, qi, or blood. The tongue also holds clues as to these imbalances. While the importance of the pulse and tongue signs is relatively unique to oriental medicine, they  often only confirm what the patient has already described during the questioning by the practitioner, and are not likely to hold all of the answers. However, skilled practitioners often use the pulses to fine tune the questioning of the patient, and get information that the patient forgot about, or did not think important. In addition, modern laboratory testing and diagnostic imaging can be helpful to differentiate and/or confirm a diagnosis.

Diagnosis
In the practice of Oriental Medical, the diagnosis is intimately tied to the etiology (development) of specific patterns of disharmony caused by imbalances in fundamental substances, dysfunctional organs, invasion by pathogens, imbalanced emotions, inappropriate lifestyle, trauma, pestilence, and other factors. Oriental medicine utilizes a  triage form of diagnosis, first treating the obvious and acute symptoms, and then isolating and treating the root cause. For example, if someone were to be treated for low back pain, the AOM practitioner might note that the individual was prone to low back injuries and pain due to a weakness in their "Kidney" physiology. In this case, the acute pain might be diagnosed and treated as a lumbar sprain/strain and blockage of Qi and Blood in Bladder Channel, and treated with acupuncture, moxa, heat, and manual therapy. Additionally, the Kidney weakness might be addressed with an herbal prescription and exercise recommendations.

Zang-Fu Imbalances
One system of Oriental medicine diagnosis classifies illnesses according to Zang-Fu "organ" imbalances. When an acupuncturist tells you that "Wind is stirring up the Liver," they are describing a specific set of signs and symptons that have traits similar to natural events and forces which everyone can recognize. In this example, the wind moves, changes, and is unsettled, but the "Liver" likes to be soothing and calm. Thus, emotional irritability combined with certain other symptoms are recognized as "Wind stirring up the Liver." Logically, it follows that that treatment would be directed to "disperse the Wind and harmonize the Liver." Certain herbs, acupuncture points, meditation, and breathing exercises might be prescribed to treat this condition, based upon a long history of scientific investigation into what comprises the most successful treatment. Lab testing can help to substantiate a zang-fu diagnosis.

Channel Dysfunctions
Another system of diagnosis In Oriental Medicine attributes, or defines as an interruption of qi or blood in the pathways, or an imbalance between the yin and yang aspects of the organs. These can often manifest as neuromusculoskeletal pain or injury, which is often confirmed by standard orthopedic and neurological examination, palpation, strength testing, and diagnostic imaging.

External Pathogens
Invasion by Wind, Cold, Summer Heat, Damp, Dryness, Fire. Pestilence.

Emotions
Execessive joy, anger, melancholy, medication, grief, fear, and fright.

Diet
Overeating and indulgance; contaminated food; too much raw food, alcohol, fats, or spices; malnourishment.

Activity
Over-exertion, lassitute, excessive sexual activity.

Trauma
Lacerations, punctures, incisions, and abrasions; sprains, strains and fractures; scalds and burns; animal bites and insect stings.

Stagnancy
Circulatory problems, blood clots, pain, hemorrhage, skin eruptions, tumors, stroke, coma.  

There is every reason to believe that Oriental Medical diagnoses will eventually be identifed and confirmed with biochemical and electromagnetic testing. Such testing itself will likely never be as cost-effective or practical as routine observation and assessment, but it can be very useful to fine tune diagnosis and treatment, and perhaps lead to the development of "computerized diagnostic assistants" such as are being used more and more in modern medicine.