Epididymitis is a common male disease, many people do not understand the epididymis, the epididymis is a necessary route for sperm, or the organ that breeds sperm, so once the epididymis has a problem, it may cause male infertility, epididymitis will have scrotal swelling and pain, sinking feeling, the following look at what causes epididymitis. 1. Acute non-specific testicular epididymitis: Acute non-specific testicular epididymitis occurs mostly in patients with urethritis, cystitis, prostatitis, prostate enlargement after resection and long-term indwelling catheterized testicular epididymitis. The infection spreads to the epididymis via lymph or vas deferens and causes epididymitis. The common causative agents are Escherichia coli, Proteus mirabilis, Staphylococcus and Pseudomonas aeruginosa. The bacteria can spread to the testis via bloodstream and cause simple testicular epididymitis. However, the testis is rich in blood flow and has strong resistance to infection, so this is less common. 2. Acute mumps orchitis: Mumps is the most common cause of testicular epididymitis, and about 20% of mumps patients have testicular epididymitis as a complication. It is mostly seen in late adolescence. The testes are highly enlarged and purplish-blue to the naked eye. When the testis is incised, the testicular tubules cannot be extruded due to interstitial reaction and edema. Histological observation shows edema with vasodilatation, massive inflammatory cell infiltration, and varying degrees of degeneration of the spermatogenic tubules. In the healing of orchitis, the testes become smaller and softer. It can also be caused by mycobacteria, spirochetes, parasitic infections, such as testicular syphilis, and granulomatous testicular epididymitis can occur in those with previous testicular trauma. Local or systemic radioisotope phosphorus irradiation of the testes can also occur as testicular inflammation and destruction of testicular tissue.