One of several different systems of diagnosis in Chinese medicine. This system can be contrasted with Six Channels diagnosis, Four Levels diagnosis, Eight Principles, and Zang Fu diagnosis. San Jiao diagnosis deals with the invasion of the body by damp External Pathogenic Factors. It outlines how a pathogen invades the body from the exterior levels to the deep internal levels, stage by stage, how to diagnose and treat the disease at each stage, and how the natural untreated progression of the disease will eventually lead to death.