What are the causes of penile edema?

Causes of Penile Edema

Penile edema results from infectious, traumatic, vascular, or idiopathic etiologies, with infectious causes (particularly epididymo-orchitis and sexually transmitted infections) being most common and requiring immediate evaluation to exclude surgical emergencies.

Infectious Causes

Sexually Transmitted Infections

• Gonococcal and chlamydial infections are the most common infectious causes in sexually active men under 35 years, often presenting with associated urethritis and penile edema 1, 2
• Penile edema occurs in approximately 1.7 per 1,000 male visits to STD clinics, with 40% having coexisting gonococcal urethritis 3
• Genital herpes (12%) and genital scabies (12%) are significantly associated with penile edema 3
• Infected penile lesions coexist in 36% of cases with penile edema 3

Epididymo-Orchitis

• Chlamydia trachomatis and Neisseria gonorrhoeae are the predominant organisms in men under 35 years 1
• Enteric organisms cause epididymitis in older men or those with urinary tract abnormalities 2
• In immunosuppressed patients, fungi and mycobacteria become more likely causative organisms 1

Necrotizing Infections

• Fournier gangrene involves the scrotum and penis with insidious or explosive onset, mean age 50 years, most commonly in diabetic patients 4
• Mixed aerobic and anaerobic flora including staphylococci and Pseudomonas species cause most cases 4
• The infection extends along fascial planes from perianal, retroperitoneal, or urinary tract sources 4

Traumatic Causes

Friction-Related Edema

• Penis friction edema results from vigorous sexual activity causing traumatic lymphatic drainage disruption 5
• This manifests as local or total penile edema or cordlike congestion of lymphatic vessels 5
• The condition is self-limited and resolves with temporary abstinence from sexual intercourse 5

Vascular Trauma

• Superficial penile dorsal vein rupture occurs during manipulation of the erect penis, presenting with acute penile edema and ecchymosis 6
• Penile fracture and pelvic fractures can cause secondary penile edema 4

Vascular and Lymphatic Causes

Venous Obstruction

• Deep venous thrombosis can cause secondary genital edema through venous congestion 2
• Lymphatic involvement appears to be the final common pathway in many cases of penile edema 3

Structural Abnormalities

• Phimosis can contribute to penile edema through impaired lymphatic drainage 4
• Post-surgical complications following hydrocelectomy may present with persistent swelling 7

Idiopathic Causes

• Transient idiopathic primary penoscrotal edema occurs in infants, resolving spontaneously over 3 months without apparent explanation 8
• Acute erysipelatous edema of unknown etiology can affect the scrotum and penis in young men 9

Critical Diagnostic Approach

Immediate Evaluation Required

• Ultrasound with Doppler is the first-line imaging modality to distinguish between etiologies, assess testicular perfusion, and identify complications 2, 7
• Both grayscale and color Doppler must be performed to evaluate for abscess, hematoma, fluid reaccumulation, or underlying testicular mass 7

Red Flags Requiring Urgent Intervention

• Failure to improve within 3 days requires reevaluation of diagnosis and therapy 2, 7
• Persistent symptoms after antimicrobial therapy warrant comprehensive evaluation for tumor, abscess, infarction, testicular cancer, or tuberculous/fungal infection 2
• Delay beyond 6-8 hours in torsion-related cases significantly increases risk of testicular loss 2

Associated Findings to Assess

• Inguinal adenopathy is present in 52% of cases with penile edema 3
• Coexisting urethritis occurs in 36% of infectious cases 3
• Systemic signs including fever, tachycardia, and diaphoresis suggest necrotizing infection requiring immediate surgical consultation 4

Common Pitfalls

• Do not dismiss penile edema as purely venereal without excluding infectious penile lesions, urethritis, and systemic infections 3
• False-negative Doppler evaluations can occur in partial torsion or spontaneous detorsion 2
• Hydroceles can mask testicular cancer, leading to delayed presentation of metastatic disease 7
• Early presentation may not show classic symptoms of serious underlying pathology 2