The value of epididymal protease inhibitor in differential diagnosis between obstructive azoospermia and non-obstructive azoospermia

There are no efficient and noninvasive clinical tests to distinguish between obstructive azoospermia (OA) and non-obstructive azoospermia (NOA). Epididymal protease inhibitor (Eppin) protein is secreted specifically by testes and epididymides in male reproductive system. It does not exist in seminal plasma of patients with OA in theory. The seminal plasma from 40 normal men and 46 azoospermic patients was detected via Western blot for investigating the presence and characteristics of Eppin protein to distinguish between OA and NOA. The cases were diagnosed as NOA whether Eppin in seminal plasma was positive via Western blot analysis. The cases were diagnosed as OA when samples were Eppin-negative. Additionally, percutaneous epididymal sperm aspiration (PESA) and percutaneous testicular sperm aspiration (PTSA) were performed on these patients at the same time as the diagnostic criteria to compare with Western blot analysis. Eppin detection in seminal plasma showed similar effectivity with PESA/PTSA in differential diagnosis between OA and NOA. Compared with PESA/PTSA, Eppin detection is a new, efficient and noninvasive method which has good clinical application.