What are the causes of hydrocele in adults?

Causes of Hydrocele in Adults

Hydroceles in adults result from an imbalance between fluid secretion and reabsorption by the tunica vaginalis, with causes broadly categorized as primary (idiopathic) or secondary to underlying pathology. 1

Primary (Idiopathic) Hydrocele

• The most common type in adults is idiopathic hydrocele, caused by impaired protein outflow from the tunica vaginalis cavity rather than fluid outflow obstruction. 2
• The mechanism involves obstruction of pores in the intercellular cement substance of the seroendothelial membrane, leading to protein and cholesterol retention that increases osmotic pressure and traps fluid within the sac. 2
• Fluid continues to flow at nearly normal rates, but accumulates due to the increased osmotic gradient created by retained proteins. 2

Secondary Hydrocele Causes

Infectious/Inflammatory Etiologies

• Epididymo-orchitis is the most common infectious cause in adults, representing approximately 600,000 cases annually in the United States, and can present with bilateral hydroceles, scrotal wall thickening, and increased vascularity. 3, 4
• In sexually active young adults, Chlamydia trachomatis and Neisseria gonorrhoeae are typical pathogens, while enteric organisms predominate in men over 35 years. 5

Iatrogenic Causes

• Varicocelectomy is the second most common cause of hydrocele in adolescents and young adults, with higher risk in non-artery-sparing procedures or those performed without microsurgical aid. 6
• Any surgery requiring cord dissection increases hydrocele formation risk. 6

Trauma-Induced

• Direct scrotal trauma can disrupt the normal fluid balance mechanisms of the tunica vaginalis. 7

Tumor-Associated

• In adolescents and young adults, "complex hydrocele" on ultrasound warrants high suspicion for underlying testicular malignancy, as infertile males have an 18-fold higher risk of testicular cancer. 4
• Testicular cancer should be included in the differential diagnosis of persistent scrotal pathology after completing antimicrobial treatment. 5

Lymphatic Obstruction

• Acquired hydroceles can result from lymphatic obstruction that impairs protein drainage from the tunica vaginalis. 2
• This mechanism may involve filariasis in endemic regions or other causes of lymphatic compromise. 7

Critical Diagnostic Considerations

• Scrotal ultrasound with Doppler is mandatory to rule out surgical emergencies (testicular torsion, inguinal hernia) and underlying pathology, with sensitivity of 96-100% for confirming normal testicular blood flow. 4
• Physical examination with orchidometer is adequate for routine volume assessment, but ultrasound should be performed for large hydroceles, thickened scrotal skin, or concern for underlying pathology. 4
• Bilateral hydroceles in men of reproductive age require fertility evaluation, as they can contribute to infertility through increased scrotal temperature and testicular dysfunction. 4

Common Pitfalls

• Do not delay evaluation of acute scrotal swelling, as testicular torsion must be ruled out emergently—testicular viability is compromised after 6-8 hours. 4
• Do not confuse hydrocele with inguinal hernia, which requires prompt surgical intervention rather than observation. 4
• In adults with persistent or complex hydroceles, failure to evaluate for underlying malignancy can result in delayed cancer diagnosis. 4