What are the potential causes and recommended evaluation for a 3.5cm long testicle, and what treatment options are available?

Assessment of a 3.5cm Testicular Length

A testicular length of 3.5cm corresponds to a volume of approximately 10-12ml, which falls at or just below the critical 12ml threshold that defines testicular atrophy and warrants comprehensive evaluation for impaired spermatogenesis, increased cancer risk, and potential underlying pathology. 1

Understanding the Clinical Significance

Testicular volumes below 12ml are definitively considered atrophic and associated with significant pathology, including:

• Impaired spermatogenesis with reduced total sperm count and sperm concentration 1
• Increased risk of intratubular germ cell neoplasia (TIN), particularly in high-risk populations 1
• Potential infertility due to compromised testicular function 1

The American Urological Association indicates that a 4cm testicular length corresponds to approximately 15-18ml volume, meaning your 3.5cm measurement represents a borderline-small to atrophic testis requiring further investigation. 1

Immediate Evaluation Required

Physical Examination Priorities

Perform a focused scrotal examination assessing for: 2

• Testicular consistency (firm vs. soft, which may indicate different pathologies) 2
• Bilateral testicular size comparison - size discrepancy >2ml or 20% warrants ultrasound to exclude pathology 1
• Presence of varicocele (more prominent when standing, less when supine) 2
• Epididymal abnormalities or enlargement 1
• Vas deferens patency 1

Critical History Elements

Obtain detailed history focusing on: 1

• History of cryptorchidism (undescended testicle) - this substantially increases cancer risk and is associated with smaller testicular volumes 2, 1
• Infertility concerns or difficulty conceiving 1
• Family history of testicular cancer 1
• Prior testicular trauma or surgery 1
• Age - men under 30-40 years with volume <12ml have significantly elevated cancer risk 1

Diagnostic Workup Algorithm

Step 1: Scrotal Ultrasound with Doppler

Order high-frequency (>10 MHz) scrotal ultrasound immediately to: 1

• Confirm accurate testicular volume using the Lambert formula (Length × Width × Height × 0.71) 1
• Identify any intratesticular masses - any solid intratesticular mass must be managed as malignant until proven otherwise 3
• Assess for structural abnormalities including varicocele, epididymal pathology, or hydrocele 1
• Compare bilateral testicular measurements precisely 1

Common pitfall to avoid: The traditional ellipsoid formula (0.52 coefficient) systematically underestimates testicular volume by 20-30% and should not be used for clinical decision-making. 1

Step 2: Hormonal Evaluation

Obtain comprehensive hormonal panel: 1

• FSH (Follicle-Stimulating Hormone) - elevated FSH with small testes indicates primary testicular failure 1
• LH (Luteinizing Hormone) - helps distinguish primary vs. secondary hypogonadism 1
• Total testosterone - assess for hypogonadism 1
• Consider SHBG to calculate free testosterone for more accurate assessment 1

The pattern of gonadotropins distinguishes primary testicular dysfunction (elevated FSH/LH with low testosterone) from secondary causes (low FSH/LH with low testosterone). 1

Step 3: Semen Analysis (If Fertility Relevant)

Perform semen analysis to assess: 1

• Sperm concentration - testicular volume strongly correlates with total sperm count 1
• Motility and morphology 1
• If severe oligospermia (<5 million/ml) or azoospermia is present, obtain karyotype testing as chromosomal abnormalities occur in 10% of these patients 1

Risk Stratification and Management

HIGH-RISK Scenarios Requiring Urgent Urology Referral

Refer immediately to urology if ANY of the following are present: 1

1. Age <30-40 years with testicular volume <12ml - carries ≥34% risk of intratubular germ cell neoplasia if testicular cancer develops in the contralateral testis 1

2. History of cryptorchidism - substantially increases cancer risk and mandates closer surveillance 1

3. Any palpable or ultrasound-detected testicular mass - requires radical inguinal orchiectomy, not scrotal biopsy 3

4. Bilateral small testes (<12ml) with infertility - may require testicular biopsy to screen for TIN 1

5. Rapid testicular atrophy or progressive size decrease 1

Moderate-Risk Scenarios

For patients with borderline volumes (10-12ml) without high-risk features: 1

• Repeat semen analysis every 6 months to detect early decline in sperm parameters 1
• Teach testicular self-examination given increased cancer risk with smaller volumes 1
• Monitor hormonal parameters annually (FSH, LH, testosterone) 1
• Consider fertility preservation counseling including sperm banking if planning future fertility 1

Special Considerations

If Testicular Cancer Risk is Identified

Before any surgical intervention: 3

• Draw serum tumor markers (AFP, β-HCG, LDH) - essential for diagnosis, staging, and monitoring 3
• Discuss fertility preservation and offer sperm banking in reproductive-age men 3
• Proceed with radical inguinal orchiectomy if intratesticular mass confirmed - never perform scrotal biopsy or scrotal incision for suspected malignancy 3

If History of Cryptorchidism is Present

The combination of cryptorchidism history and testicular atrophy (<12ml) warrants testicular biopsy to screen for intratubular germ cell neoplasia, as untreated TIN develops into invasive testicular tumor in 70% of cases within 7 years. 1

Primary care providers should refer infants with cryptorchidism who do not have spontaneous testicular descent by six months (corrected for gestational age) to surgical specialists, as testes remaining undescended are unlikely to descend spontaneously and suffer continued damage. 2

Long-Term Monitoring

Establish surveillance protocol: 1

• Clinical examination every 6-12 months depending on risk factors 1
• Annual hormonal evaluation if baseline abnormalities present 1
• Repeat ultrasound if clinical changes occur (new mass, pain, rapid size change) 1
• Lifelong testicular self-examination education 3

Critical pitfall: Never assume a small testis is simply "normal variation" without completing the full diagnostic workup, as this measurement represents a clinically significant finding requiring systematic evaluation to exclude serious pathology. 1