Clinical meaning
Orchitis is inflammation of the testis, most commonly caused by viral or bacterial infection. Viral orchitis is most often associated with the mumps virus - mumps orchitis typically develops 4-8 days after parotid gland swelling and affects post-pubertal males. Bacterial orchitis usually occurs as an extension of epididymitis (epididymo-orchitis) caused by urinary tract pathogens or sexually transmitted organisms. The infection and resulting inflammation cause testicular swelling, pain, warmth, and erythema. Inflammation can damage the seminiferous tubules where sperm are produced, potentially leading to testicular atrophy and infertility. It is critical to differentiate orchitis from testicular torsion - torsion is a SURGICAL EMERGENCY where the spermatic cord twists, cutting off blood supply to the testis. Torsion presents with sudden onset severe pain, whereas orchitis typically has a more gradual onset with fever.
Exam relevance
Risk factors: - Mumps infection (especially in unvaccinated post-pubertal males) - Sexually transmitted infections (gonorrhea, chlamydia) - Urinary tract infections - Epididymitis - Immunosuppression - Lack of MMR vaccination - Urinary catheterization or instrumentation