Epididymo-Orchitis

Epididymo orchitis is inflammation of the epididymis with involvement of the testis, found in about 20 to 40% of those with epididymitis. It is the commonest cause of acute scrotal pain in adult men, and presents over 1 to 3 days.

It is mostly bacterial. The likely organism depends on age and sexual history, and treatment is started before the culture result.

Pathophysiology. Organisms ascend from the urethra or bladder through the vas to the epididymis. Venous congestion from swelling can compromise testicular blood flow.

Causes by group:

• Under 35 or sexually active: Chlamydia trachomatis and Neisseria gonorrhoeae, and less often Mycoplasma genitalium.
• Over 35, after instrumentation, with bladder outlet obstruction, catheters or urinary tract anomalies: Escherichia coli, other Enterobacterales, Pseudomonas and Enterococcus.
• Men practising insertive anal sex: enteric organisms.
• Less common: tuberculosis, brucellosis, mumps (testis predominant), fungal infection in the immunosuppressed, and BCG after intravesical therapy.
• Non-infective: amiodarone (dose related, usually 200 mg daily or more), Behçet disease, vasculitis and IgG4-related disease.

Complications: abscess, testicular infarction, chronic epididymitis and pain, and reduced fertility.

Gradual onset of unilateral scrotal pain and swelling, with fever, urethral discharge, dysuria and frequency. The epididymis is tender and swollen, usually starting at the tail, with a reactive hydrocele and erythema of the scrotal skin. Elevation of the testis may relieve pain, but this is unreliable.

Sudden onset in a young man under 25 means torsion until excluded. Fever with rigors, spreading erythema, crepitus or severe pain suggests abscess or necrotising infection.

• First void urine or urethral swab nucleic acid test for Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma genitalium. Urethral Gram stain showing 5 or more polymorphs in each high power field suggests urethritis.
• Midstream urine culture and urinalysis.
• Full blood count, C-reactive protein, creatinine, blood cultures if febrile, and HIV and syphilis serology.
• Doppler ultrasound when torsion cannot be excluded, or when abscess, tumour or an unusual course is suspected: an enlarged hyperaemic epididymis and testis with a reactive hydrocele, and increased flow.
• When sterile pyuria is present: urine for acid fast bacilli and culture. Brucella serology after livestock or unpasteurised milk exposure. Amiodarone history.

Differential diagnosis.

• Testicular torsion
• Torsion of the appendix testis
• Testicular tumour
• Inguinal hernia
• Trauma with haematocele
• Henoch-Schonlein purpura
• Idiopathic scrotal oedema
• Mumps orchitis
• Epididymal cyst or spermatocele with infection

• Take samples first, then start antibiotics at once.
• Likely sexually transmitted: ceftriaxone 1 g intramuscularly as a single dose plus doxycycline 100 mg orally twice daily for 10 to 14 days. If Mycoplasma genitalium is detected, base treatment on resistance testing: doxycycline 100 mg twice daily for 7 days followed by moxifloxacin 400 mg orally once daily for 7 days is a common regimen.
• Likely enteric or urinary: ciprofloxacin 500 mg orally twice daily for 10 to 14 days, with the dose reduced to 250 to 500 mg every 12 hours when eGFR is 30 to 50, and every 24 hours when eGFR is under 30. Fluoroquinolone cautions: tendon rupture, QT prolongation, dysglycaemia, aortic aneurysm and neuropsychiatric effects. Alternative when the organism is susceptible: co-trimoxazole 960 mg orally twice daily for 14 days (halved when eGFR is 15 to 30, avoided when under 15).
• Admission for sepsis, severe pain, abscess, vomiting or immunosuppression: ceftriaxone 2 g intravenously once daily, with culture directed changes, then oral treatment to complete 10 to 14 days. Add metronidazole 500 mg intravenously every 8 hours if anaerobes or abscess are suspected.
• Symptom care: bed rest for 1 to 2 days, scrotal 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.
• Partners of men with a sexually transmitted cause are tested and treated, and sex is avoided until both have completed treatment and symptoms settle (at least 7 days). Offer HIV and syphilis testing and vaccination as needed.
• Mumps: supportive care only. Tuberculosis: a 6-month regimen of 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.
• Amiodarone: reduce the dose or change the drug with the cardiologist, and avoid antibiotics unless infection is shown.
• Abscess, infarction or failure to improve in 48 to 72 hours: surgical exploration, drainage, and orchidectomy if the testis is non-viable.
• Chronic epididymitis (symptoms over 3 months): culture directed antibiotics for 4 to 6 weeks when infection is found, then analgesia, neuropathic agents (amitriptyline 10 mg at night, titrated to 50 mg) and pelvic floor therapy.

Special groups. Boys and men with a first episode and no sexual risk need urine culture and ultrasound of the urinary tract for an anomaly. Men with HIV and diabetes need longer follow up for abscess.

Monitoring. Review at 48 to 72 hours for response. Review again at 2 weeks. Swelling may take 4 to 6 weeks to settle. An indurated mass persisting over 6 weeks needs ultrasound to exclude tumour.

Referral and escalation. Refer to urology if there is no improvement in 72 hours, recurrent or chronic disease, or suspected tuberculosis. Urgent referral for suspected torsion, abscess, sepsis or necrotising infection.