Risk Factors for Orchitis
The primary risk factors for orchitis include age under 35 years with sexually transmitted infections (particularly Chlamydia trachomatis and Neisseria gonorrhoeae), age over 35 years with urinary tract infections (particularly E. coli), mumps virus infection, and immunosuppression. 1
Age-Related Risk Factors
Young Adults (Under 35 Years)
- Sexually transmitted infections (STIs) are the predominant cause 2, 1
- Chlamydia trachomatis (most common in this age group) 3
- Neisseria gonorrhoeae
- High-risk sexual behaviors 2
- Multiple sexual partners 2
Older Adults (Over 35 Years)
- Urinary tract infections with enteric organisms 2, 1
- E. coli (most common bacterial cause in this age group) 3
- Urinary tract abnormalities 4
- Bladder outlet obstruction 5
- Benign prostatic hyperplasia 5
- Recent urinary tract instrumentation or procedures 2
Infectious Risk Factors
Viral Causes
- Mumps virus (most common viral cause) 1
- Other viral pathogens 1:
- Coxsackie virus
- Rubella virus
- Epstein-Barr virus
- Varicella zoster virus
Bacterial Causes
- Retrograde spread from epididymitis (most common route for bacterial orchitis) 1
- Hematogenous spread (less common) 6
Other Risk Factors
- HIV infection (increases risk of fungal and mycobacterial orchitis) 2
- Immunosuppression (higher risk of atypical pathogens) 1
- Anatomical abnormalities of the urinary tract 4
- Recent genitourinary procedures 2
- Geographic and demographic factors (higher rates in certain communities) 2
- Socioeconomic factors (poverty, discrimination) 2
Clinical Pearls
- Isolated orchitis is less common than epididymo-orchitis, which typically begins as epididymitis with retrograde spread to the testis 1
- Always consider testicular torsion in the differential diagnosis of acute testicular pain, especially in adolescents, as it requires emergency surgical intervention within 4-6 hours 5
- Mumps orchitis can lead to testicular atrophy and infertility, especially when bilateral 1
- In patients with suspected STI-related orchitis, sexual partners should be evaluated and treated 4
- Patients with severe symptoms or systemic illness should be referred for parenteral therapy 4
Understanding these risk factors can help guide appropriate diagnostic testing and empiric treatment while awaiting culture results, potentially reducing complications such as testicular atrophy, abscess formation, and infertility.