Orchitis is an inflammation of the testis, usually acute. It is caused by bacteria or viruses. When the inflammation involves only the epididymis (which is a tubular structure close to the testis, where the spermatozoa pass through), it is called epididymitis. The inflammation of both structures (epididymitis-orchitis) is not rare.
Often the onset is acute, with scrotum swelling, enlarged and hard testis, and local pain, sometimes with fever and/or nausea.
The infection affects often men younger than 35. Also older patients with urinary infections or indwelling catheter are at risk. The inflammation is due to ascending infection from the urethra or the prostate, along the sperm cord, to contaminate the testis and/or epididymis. Common urinary bacteria, like Escherichia Coli, Streptococcus, Staphylococcus, Enterococcus, Proteus, Klebsiella, are involved. Seldom Gonococcus urethritis can be complicated by an orchitis. In western countries tuberculous orchitis is rare.
Viral orchitis during mumps parotitis may impair fertility in postpuberal men.
The diagnosis is based upon clinical presentation, and in any case of doubt on scrotal ultrasound. Before starting antibiotic therapy, it can be useful a culture of urine, urethral secrete, and semen, to identify the responsible bacteria and to choose a specific antibiotic. The therapy should be continued for 10 days. Testis enlargement can last for weeks.
Recurrent infection may cause chronic epididymitis, with permanently enlarged and hard epididymis.