Description
Orchitis refers to the inflammation of one or both testes, often due to an infection. The condition often presents with unilateral testicular pain, swelling, fever and malaise. While the infection can be bacterial in nature, viral orchitis is also common, particularly due to the mumps virus.
Pathogenesis
Orchitis is typically caused by the spread of a bacterial or viral infection from the epididymis (epididymo-orchitis), the most common cause being viral mumps orchitis. In bacterial orchitis, sexually transmitted bacteria, such as Neisseria gonorrhoeae and Chlamydia trachomatis, are usually the causative agents in sexually active men, while Escherichia coli and other typical urinary pathogens are more commonly seen in older or uncircumcised men. Bacterial orchitis usually arises secondary to epididymitis, prostatitis, or urinary tract infections.
Epidemiology, Risk Factors & Associations
- Orchitis predominantly affects adult men, with mumps orchitis being most common in post-pubertal males (20-30% of post-pubertal males with mumps will develop orchitis).
- Risk factors include unprotected sexual intercourse (for bacterial orchitis), lack of vaccination against mumps, recurrent urinary tract infections, and anatomical abnormalities of the urinary tract.
Clinical Features
- Patients often present with acute scrotal pain and swelling, which may be accompanied by systemic symptoms such as fever and malaise.
- In cases of mumps orchitis, parotitis often precedes the onset of orchitis by about a week.
Complications
- Possible complications of orchitis include testicular atrophy, infertility (particularly with bilateral involvement), and rarely, abscess formation.
Pathological Features
Histopathology
- Orchitis shows diffuse or focal testicular inflammation, with an infiltrate that can include neutrophils, lymphocytes and plasma cells, depending on the causative agent. In severe cases, abscess formation can occur.
Serology
- In bacterial orchitis, cultures and gram stains of urine or urethral discharges can be helpful.
Radiological Features
Ultrasound
- Ultrasound is the most commonly used imaging modality for orchitis. It shows enlarged and hypoechoic testes, often with increased blood flow on Doppler imaging.
- In the early stage of the disease, the affected testicle might appear normal or slightly enlarged with increased vascularity.
- As the disease progresses, the echotexture becomes heterogeneous, and areas of necrosis may be seen.
- Hydrocele or pyocele can also be identified if present.
Differential Diagnosis
- Testicular torsion: Acute onset of severe testicular pain. The “bell clapper” deformity may be seen on ultrasound.
- Epididymitis: Inflammation is seen primarily in the epididymis on ultrasound.
- Testicular tumour: Presents with a painless testicular mass, often with areas of calcification on ultrasound.
Management
- Management of orchitis depends on the causative agent. Antibiotics are prescribed for bacterial orchitis, often alongside analgesics for pain control. Bed rest, scrotal elevation, and cold compresses may also be recommended.
- For mumps orchitis, treatment is primarily supportive as there is no specific antiviral treatment available.
- In cases of severe pain or complications such as abscess formation, surgical intervention may be needed.