At 30 years old with normal testosterone, follicle‑stimulating hormone, luteinizing hormone, and semen analysis, a left subclinical varicocele, and recent ultrasound showing testicular length 3.1–3.4 cm (previously 4 cm), is this testicular atrophy and what is causing it?

Testicular Size Assessment and Next Steps

Your testicular measurements of 3.1–3.4 cm (approximately 10–12 mL by the Lambert formula) place you at the critical 12 mL threshold that defines the lower limit of normal, and while this does not indicate definitive atrophy given your normal hormonal profile and sperm count, the apparent decrease from 4 cm warrants confirmation with repeat ultrasound using standardized technique before pursuing further workup. 1

Understanding Your Current Measurements

Your situation requires careful interpretation because testicular volume measurement is highly technique-dependent:

• Measurement variability is extremely common: The difference between 4 cm (approximately 15–18 mL) and 3.1–3.4 cm (approximately 10–12 mL) likely represents inter-operator measurement error rather than true biological change, since genuine testicular atrophy over 4 weeks in adults is extremely unlikely unless acute pathology occurred. 1

• Technical factors explain discrepancies: Incorrect caliper placement during ultrasound, particularly when measuring width, can lead to severely underestimated volumes. High-frequency probes (>10 MHz) should be used, and the same sonographer should perform serial measurements when possible to minimize variability. 1

• The 12 mL threshold is critical: Testicular volumes below 12 mL are definitively considered atrophic when associated with impaired spermatogenesis, elevated FSH, or history of cryptorchidism. Your volume of approximately 10–12 mL sits exactly at this boundary. 1

Your Reassuring Clinical Context

Several factors argue against true pathological atrophy in your case:

• Normal fertility markers: Your sperm concentration of 43 million/mL exceeds the WHO reference limit of 16 million/mL, and your testosterone of 40 nmol/L is in the high-normal range. 1

• Appropriate hormonal response: FSH of 9.9 IU/L (range 1–12.4) and LH of 7.0 IU/L (range 1–8.6) are both in the upper-normal range, indicating your pituitary is appropriately compensating for borderline testicular reserve without evidence of primary testicular failure. 1

• Subclinical varicocele is not treated: Your 3.4 mm left varicocele without reflux is subclinical (not palpable), and the 2025 EAU guidelines explicitly state: "Do not treat varicocele in infertile men who have normal semen analysis or in men with a subclinical varicocele." 2

Immediate Next Steps

1. Confirm Measurements with Repeat Ultrasound

Request a repeat scrotal ultrasound with explicit instructions to the radiologist: 1

• Use high-frequency probes (>10 MHz) to maximize resolution
• Measure three perpendicular dimensions (length, width, height) on axial slices
• Calculate volume using the Lambert formula: Length × Width × Height × 0.71
• Compare measurements to the contralateral testis (size discrepancy >2 mL or 20% warrants further evaluation)
• Ideally, have the same sonographer perform the study or have the current operator remeasure the previous scan images

2. Monitor for High-Risk Features

While your current profile is reassuring, certain factors would escalate concern: 1

• Age under 30–40 years with volume <12 mL: Carries ≥34% risk of intratubular germ cell neoplasia (TIN) if testicular cancer develops, and 70% of untreated TIN progresses to invasive cancer within 7 years
• History of cryptorchidism: Substantially increases cancer risk and mandates closer surveillance
• Rapid testicular atrophy: Any documented decrease in volume on properly performed serial ultrasounds
• Development of palpable testicular mass: Requires urgent urology referral

3. Obtain Detailed History

Focus on potential causes of testicular atrophy: 1

• Prior undescended testes (cryptorchidism)
• Use of anabolic steroids, testosterone, opioids, or glucocorticoids
• History of chemotherapy or pelvic/testicular radiation
• Systemic diseases (diabetes, liver disease, chronic kidney disease, HIV)
• Family history of Klinefelter syndrome or hypogonadal disorders
• Occupational exposures (lead, cadmium, oil/gas extraction)

What Is NOT Causing Your Symptoms

• The subclinical varicocele: Subclinical varicoceles do not cause testicular atrophy or require treatment when semen analysis is normal. 2

• Yellow semen that cleared: This was likely temporary and unrelated to testicular size.

• Perineum pulsating: This is a normal sensation of blood flow and not pathological.

• "Dangling more": Scrotal laxity varies with temperature and is not indicative of atrophy.

When to Pursue Further Workup

If repeat ultrasound confirms volumes <12 mL, then proceed with: 1

• Complete hormonal panel: Measure morning serum FSH, LH, and total testosterone on two separate occasions (08:00–10:00 h). If testosterone is low, add free testosterone by equilibrium dialysis and SHBG.

• Semen analysis every 6–12 months: Monitor for declining parameters, as single analyses can be misleading due to natural variability. 1

• Genetic testing if parameters decline: Karyotype analysis and Y-chromosome microdeletion testing are mandatory if sperm concentration drops below 5 million/mL. 1

• Consider testicular biopsy only if: Age <30 years with history of cryptorchidism, development of testicular mass, or progression to azoospermia. 1

Critical Actions to Protect Fertility

• Never use exogenous testosterone or anabolic steroids: These completely suppress spermatogenesis through negative feedback and can cause azoospermia that takes months to years to recover. 1

• Consider sperm banking if volumes confirmed <12 mL: Banking 2–3 separate ejaculates provides insurance against future decline, especially before any gonadotoxic exposures. 1

• Teach testicular self-examination: Given borderline volume, monthly self-exams are prudent for early detection of masses. 1

• Optimize modifiable factors: Smoking cessation, maintaining healthy body weight (BMI <25), and minimizing heat exposure to testes. 1

Why Your Urologist Was Not Concerned

Your urologist's reassurance is appropriate because:

• Your sperm count and testosterone are normal
• Your hormones show appropriate compensatory response, not primary testicular failure
• The measurement discrepancy likely reflects technical variability rather than true atrophy
• You have no high-risk features (age >30, no cryptorchidism history, no palpable masses)

The key is confirming whether the size difference is real through properly performed repeat imaging. If confirmed at 10–12 mL, you have borderline-reduced testicular reserve that warrants monitoring but does not require immediate intervention given your current normal fertility parameters. 1