Orchitis

Orchitis is inflammation of the testis without prominent involvement of the epididymis. The commonest cause is viral, mainly the mumps virus. Bacterial orchitis usually accompanies epididymitis.

Mumps orchitis develops in about 15 to 30% of postpubertal males with mumps, usually 4 to 8 days after the onset of parotitis, though it can occur without parotitis. It is unilateral in about 70 to 80% of cases and bilateral in the rest.

Pathophysiology. Viral invasion and immune mediated injury cause interstitial oedema and inflammation. Swelling inside the tight tunica albuginea raises pressure and can cause ischaemic injury to the seminiferous tubules.

Other causes:

• Viral: coxsackie B, echovirus, Epstein-Barr virus, varicella, parvovirus B19, HIV and SARS-CoV-2.
• Bacterial and other infection: syphilis, brucellosis, tuberculosis and fungal infection.
• Granulomatous orchitis, sarcoidosis and autoimmune orchitis.
• Vasculitis (polyarteritis nodosa, Henoch-Schonlein purpura, Behçet disease).

Late effects: atrophy in about 30 to 50% of affected testes, reduced sperm count in a proportion of men, and rarely infertility, particularly with bilateral disease.

Sudden testicular pain and swelling, fever, rigors, headache, malaise and nausea. The testis is large, tender and firm, the scrotal skin is red and warm, and a reactive hydrocele may be present. Parotitis, or contact with mumps, supports a viral cause. Torsion must be excluded when onset is abrupt.

• Doppler ultrasound: an enlarged, hypoechoic or heterogeneous testis with increased flow. It also excludes torsion, abscess and tumour.
• Mumps: serum IgM, and polymerase chain reaction on saliva, throat or urine, ideally within 5 days of onset.
• Full blood count (leucopenia with lymphocytosis suggests a viral cause), C-reactive protein, urinalysis and culture, and first void urine nucleic acid test for Chlamydia trachomatis and Neisseria gonorrhoeae.
• Syphilis, HIV and brucella serology, and tuberculosis testing when suggested.
• Semen analysis at 3 months in adults, particularly after bilateral disease. Morning testosterone and FSH for bilateral disease.

Differential diagnosis.

• Testicular torsion
• Epididymo orchitis
• Testicular tumour or lymphoma
• Testicular infarction
• Testicular abscess
• Vasculitis
• Granulomatous orchitis
• Trauma

• Viral orchitis: supportive care with rest, scrotal elevation and support, ice, ibuprofen 400 mg orally every 8 hours with food (maximum 2.4 g daily) and paracetamol 1 g every 6 hours (maximum 4 g daily). Morphine 2 to 5 mg intravenously for severe pain. A spermatic cord block with lidocaine 1% may relieve severe pain.
• Corticosteroids and interferon alfa have been used with weak evidence, and are not routine.
• Bacterial orchitis: antibiotic choice depends on the likely organism. Likely sexually transmitted: ceftriaxone 1 g intramuscularly once plus doxycycline 100 mg orally twice daily for 10 to 14 days. Likely enteric: ciprofloxacin 500 mg orally twice daily for 10 to 14 days, with the dose reduced when eGFR is under 50.
• Tuberculous orchitis: isoniazid 5 mg/kg (maximum 300 mg), rifampicin 10 mg/kg (maximum 600 mg), pyrazinamide 25 mg/kg and ethambutol 15 mg/kg for 2 months, then isoniazid and rifampicin for 4 months, with pyridoxine 10 to 25 mg daily.
• Brucellosis: doxycycline 100 mg twice daily plus rifampicin 600 to 900 mg once daily for 6 weeks. Syphilis: benzathine benzylpenicillin 2.4 million units intramuscularly weekly for 3 weeks for late disease, and once for early disease.
• Vasculitis and autoimmune orchitis: treat the cause, usually with prednisolone 0.5 to 1 mg/kg orally once daily and specialist review.
• Surgery: testicular fasciotomy (incision of the tunica albuginea) for refractory pain with raised intratesticular pressure, and exploration for abscess, infarction or diagnostic doubt.
• Prevention of mumps orchitis: two doses of measles, mumps and rubella vaccine. Isolate until 5 days after parotitis onset.
• Cryopreserve semen when bilateral disease occurs in a man wanting children.

Monitoring. Review at 48 to 72 hours, at 2 weeks, and at 6 weeks. Ultrasound for testicular size at 3 months. Semen analysis at 3 and 6 months, and testosterone in bilateral disease.

Referral and escalation. Refer to urology for diagnostic doubt, abscess, bilateral disease or persisting pain. Urgent referral for suspected torsion.