[A study on evolution of the term impotence and its classification and diagnosis].

Called "bu qi" (unable to erect) in the pre-Qin period, it was called "yin wei" (yin flabbiness) during Qin-Han to Jin-yuan dynasties, and called "yang wei" (yang flabbiness) since the Ming dynasty, though a few books called it Yin-flabbiness, but both Yang- and Yin- flabbiness didn't appear simultaneously in the same work. It was categorized under seven-injuries, kidney disorders, consumptive diseases, five non-masculine and sexual diseases before the Tang dynasty, and categorized under miscellaneous diseases since Jin dynasty. It was typed into bu ju (non erected), bu jian (non hardened) and bu jiu (non persistent). Some classified on the basis of etiology. It was pointed out that this disorder refers to inability to errect though the patient has a desire to erect, instead of unwilling to erect. The changes of the idea reflect the different levels of recognition in different historical periods.