Diagnostic Methods in TCM TCM diagnosis includes diagnostic methods and differentiation of syndromes.

Diagnostic methods consist of interrogation, inspection, auscultation and olfaction, pulse-feeling and palpation. All these methods aim mainly at providing objective basis for differentiation of syndromes by collecting and signs from the patient.
As one of these methods, interrogation is to ask the patient or his companion about the history of the disease, the history of the patient's life and his family, as well as his own feeling symptoms.
Inspection is to observe, with the doctor's own eyes the patient's vitality, complexion, physical condition and behavior, picture of the tongue, secretion, excrement and so on.
Auscultation is to judge pathological changes in the interior of the patient's body by listening to his voices, while olfaction is to differentiate the internal conditions of the disease by smelling the odors emitted from the patient.

Pulse-feeling is applied to find out the prosperity or decline of the zang-organs, qi and blood by feeling the patient's pulse. On the other hand, palpation means detecting disease conditions by touching or pressing some part of the patient's body by hand.

Differentiation of syndromes refers to the process in which analysis and inference are made on the basis of clinical materials acquired through various diagnostic to determine the type of a disease.
Such modes of logical thinking as concept, inference and judgment are adopted in the differentiation of syndromes. The type of a disease is drawn from a large amount of perceptual materials.

As a pathological generalization of a disease in its certain stage, syndromes in TCM reflect the law and nature of a disease, serving as a basis for TCM treatment. Therefore, they differ from symptoms.

The techniques of differentiation of syndromes consist of the methods to differentiate pathological conditions in accordance with the eight principal syndromes, to differentiate syndromes according to the state of qi and blood, to differentiate syndromes according to pathological changes of the viscera and their interrelations, to differentiate syndromes of a febrile disease in accordance with the theory of the six channels, and to differentiate the development of an epidemic febrile disease by analyzing and studying conditions of the four syndromes, namely, wei, qi, ying and xue systems.

To differentiate pathological conditions in accordance with the eight principal syndromes is to induce and generalize a disease in guidance with such ideas as exterior and interior, excess and deficiency, coldness and heat, yin and yang to identify the location, the degree of seriousness and nature of a diseases, as well as the conditions of the vital qi in conflict with pathogenic factors. This method provides  the guiding principle for the  other methods mentioned above and reflects the common characteristics of all these methods. Therefore, it is applicable to the differentiation of the syndromes of diseases in every clinical branch of medicine. Differentiation of syndromes according to the state of qi and blood, and differentiation of syndromes according to pathological changes of the viscera and their interrelations are mainly applied to analyze and distinguish miscellaneous diseases due to disorder of the internal organs. These two methods are often used in combination with the first technique.

To differentiate syndromes of a febrile disease in accordance with the theory of the six channels, and to differentiate the development of an epidemic febrile disease by analyzing and studying the conditions of the four syndromes (wei,qi,ying and xue systems) are diagnosis for diagnosis of exopathic febrile diseases.

In TCM, some names of diseases are defined according to their cause, such as sunstroke and indigestion; some are termed according to their locations, such as boil of the tongue, acute appendicitis; some are called according to their symptoms, for instance, vomiting, diarrhea.   
 The fundamentals of TCM Diagnosis TCM diagnosis depends merely on the doctor's sense organs to acquire clinical materials, then to analyze, generalize and infer through logical thinking without resorting to any apparatus. The reason why a doctor can diagnose internal pathological changes merely by observation and analysis of external signs when he is unable to inspect the pathological changes in the interior directly is that the human body is an  organic whole, with its parts intimately and inseparately connected with each other by the channels and collaterals. The internal is related with the external, and the exterior with the interior. So pathological changes inside of the human body are inevitably shown outwardly as abnormities in complexion, spirit, picture of the tongue and the pulse. It is, therefore, possible to judge internal pathological changes by inspecting these external changes. This fundamental known as "determining the internal disturbance by observing external signs" is explained in the biological holographic treatment invented by Associate Professor Zhang Yingqing working at Shandong University. In 1973, Mr. Zhang found a new group of acupuncture points arranged in order on the side of the second metacarpal bone of man. Corresponding to each part of the viscera and limbs, they are distributed in such a way that they look like an epitome of the whole human body. When certain pathological changes occur in one of the viscera, or one part of  a man's body, there will appear a tender point in the corresponding acupoint. Moreover, if we can find out the tender point by pressing, we may infer which internal organ, or which part of the body has been involved in pathological changes. 

The rate of accuracy in diagnosis reaches more than 90 percent. Mr. Zhang also think that, in every limb, there is the same distribution law of acupoint as that of the acupoint group on the side of the second metacarpal bone. Every part of each limb corresponds with each organ and each part of the whole body. Therefore, pathological changes of the viscera may be identified from any one of the limbs. He defines such a kind of diagnosis as "biological holographic diagnostic method". In this sense, the fundamentals of the observations of the face, tongue, eyes, ears, and pulse-feeling in TCM can be explained by this theory.    The Principles of TCM Diagnosis   1. Observing Diseases by Taking the Human Body as a  Whole  Taking the human body as a whole in observing diseases has two implications. On the one hand, the human body should be taken as an organic whole while special attention is paid to the interrelation and interaction between local pathological changes and the maladjustment of the whole body. Local pathological changes may affect the whole body and pathological changes of the whole body, in turn, may be reflected in a certain part. While external diseases may penetrate into the interior, diseases of the viscera may have external manifestations. For example, dryness of the eyes is usually due to deficiency of the liver-yin, or due to deficiency of the liver-blood. Conjunctival congestion indicates heat in the liver channel, or excessive heat in the lung. So it is difficult to make a correct diagnosis merely by observing local symptoms without regarding the whole body as a whole.