Epididymo-Orchitis

Definition/diagnostic criteria Epididymo-orchitis is an inflammation of the epididymis and testis. It is predominantly a bacterial infection, commonly due to sexually transmitted infections (STIs) in men under 35 (typically Chlamydia trachomatis and Neisseria gonorrhoeae) and urinary tract pathogens in older men, notably Escherichia coli. The diagnosis is clinical, based on symptoms and physical examination, sometimes supported by laboratory tests.

Epidemiology This condition is relatively common, affecting a broad age range, with a higher prevalence in sexually active young men. In the UK, the exact incidence is unclear due to variations in reporting and diagnostic practices. However, chlamydia and gonorrhoea, significant causative agents, are among the most commonly reported STIs.

Diagnosis
Clinical features: The presentation includes unilateral testicular pain, swelling and erythema, sometimes accompanied by systemic symptoms like fever. The epididymis is often tender and swollen. It is crucial to differentiate it from testicular torsion, which is a surgical emergency – and if in doubt, to refer urgently to secondary care for assessment.

Investigations: Ideally, investigations involve urinalysis and urethral swab for nucleic acid amplification tests (NAATs) to identify causative STIs, although this may not always be possible, or possible immediately, in primary care. Typical laboratory abnormalities include pyuria and bacteriuria in urine tests, and a positive NAAT for chlamydia or gonorrhoea. Ultrasound of the scrotum is useful to rule out torsion and other pathologies in those referred urgently to hospital.

Treatment Treatment involves antibiotics, tailored to likely pathogens based on age and sexual history. For men under 35 or those with high risk of STI, a combination of ceftriaxone and doxycycline (for 10-14 days) is recommended. Oral ofloxacin (for 14 days) is an alternative. These patients should be advised to have follow-up at an STI clinic (if they can’t be seen in an STI clinic immediately). For older men, or those with likely urinary tract infection, ofloxacin (for 14 days)  or levofloxacin (for 10 days) is preferred. Analgesia and scrotal support are important adjuncts. Partners should be tested and treated to prevent reinfection and reduce STI transmission.

Prognosis The prognosis is generally good with prompt and appropriate treatment. Most cases resolve without complications. Chronic epididymitis can develop in a small number of cases. Complications such as abscess formation, infertility, or chronic pain sometimes occur.