I. Mandatory examination for each person: examination of the whole body and genitalia (testes, epididymis, vas deferens, spermatic veins, penis, prepuce and urethra, etc.). Semen routine: mainly sperm density, motility and morphology, applicable to each patient; Serum sex hormones: mainly T, FSH, LH, PRL; Anti-seminal antibodies: mainly anti-seminal antibodies on the surface of seminal plasma and sperm, applicable to poor sperm vitality, more sperm agglutination, or unexplained infertility; Chromosome analysis: including autosomal and Y chromosome microdeletion, applicable to azoospermia, extreme oligospermia, protozoospermia For azoospermia, extreme oligospermia, primary small testes, and unexplained miscarriage and fetal abortion in female; VI. Biochemical analysis of seminal plasma: a-glycosidase and fructose, reflecting the function and patency of epididymis and seminal vesicles respectively, for suspected sperm duct obstruction; VII. vesiculography: for suspected ejaculatory duct or vas deferens obstruction and ready for surgical treatment; ix. testicular biopsy (puncture or incision): for azoospermia, especially for those with normal testicular volume, FSH not significantly elevated, and ready for IVF.