From the Guidelines
Epididymo-orchitis is an inflammatory condition involving the epididymis and testis, primarily resulting from bacterial infection, with the most recent evidence suggesting that retrograde ascent of pathogens from the urethra or bladder into the epididymis and subsequently the testis is the primary pathophysiological mechanism 1. The pathophysiology of epididymo-orchitis involves:
- Retrograde ascent of pathogens, such as Neisseria gonorrhoeae and Chlamydia trachomatis, from the urethra or bladder into the epididymis and subsequently the testis
- Inflammatory cascade with neutrophil infiltration, edema, and increased blood flow to the affected tissues
- Characteristic symptoms of pain, swelling, and tenderness
- Potential complications, such as abscess formation, testicular infarction, or chronic epididymitis, if left untreated Non-infectious causes, including trauma, autoimmune reactions, or chemical irritation from urine reflux, can also trigger inflammatory responses without bacterial presence. The close anatomical connection between the epididymis and testis explains why inflammation often affects both structures simultaneously, as noted in the most recent guidelines 1. Key points to consider in the diagnosis and treatment of epididymo-orchitis include:
- Urgent surgical exploration if torsion is suspected
- Antibiotic treatment, such as ceftriaxone and a course of an antibiotic active against Chlamydia trachomatis, for suspected epididymitis
- Scrotal ultrasound examination and clinical assessment to guide diagnosis and treatment
- Consideration of parenteral therapy if severe infection is present, as recommended in the European Association of Urology guidelines 1.
From the Research
Pathophysiology of Epididymo-Orchitis
The pathophysiology of epididymo-orchitis involves the inflammation of the epididymis and testis, which can be caused by various factors, including:
- Sexually transmitted infections, such as Chlamydia trachomatis and Neisseria gonorrhoeae, which are common in men under 35 years old 2, 3, 4, 5
- Enteric organisms, such as E. coli, which can cause epididymo-orchitis in men over 35 years old, often associated with functional bladder outlet problems 2, 4, 6
- Reflux of urine into the ejaculatory ducts, which can lead to epididymitis in children and men with bladder outlet obstruction 4, 6
- Blood-borne dissemination, which can cause orchitis, particularly in cases of viral infections such as mumps 3
Routes of Infection
The routes of infection for epididymo-orchitis include:
- Retrograde ascent of pathogens, which is the usual route of infection for epididymitis 3
- Hematogenous spread, which can cause orchitis, particularly in cases of viral infections 3
- Lymphatic spread, which can also contribute to the development of epididymo-orchitis 6
Risk Factors
Risk factors for epididymo-orchitis include:
- Age, with men under 35 years old being more likely to develop sexually transmitted epididymitis, and men over 35 years old being more likely to develop epididymitis caused by enteric organisms 2, 4
- Sexual activity, with sexually active men being at higher risk of developing epididymo-orchitis caused by sexually transmitted infections 2, 4, 5
- Underlying urologic abnormalities, such as bladder outlet obstruction, which can increase the risk of developing epididymo-orchitis 2, 4, 6