I am a 30‑year‑old male with progressive testicular shrinkage, normal testosterone, normal sperm concentration, normal follicle‑stimulating hormone, a subclinical varicocele, no pain, and scrotal ultrasound showing small testicular volume (~9 mL bilaterally); is this likely benign and unrelated to the varicocele?

Testicular Volume of 9 mL Bilaterally with Normal Sperm Parameters: Assessment and Implications

Your ultrasound measurement of 9 mL bilaterally is almost certainly a technical error, given your normal testosterone (30 nmol/L), normal sperm concentration (46 million/mL), and normal FSH (9.5 IU/L). 1

Why the 9 mL Measurement is Likely Incorrect

Technical errors in ultrasound caliper placement are extremely common and can underestimate testicular volume by 20–30%, particularly when the width dimension is measured incorrectly. 1 True bilateral testicular atrophy of 9 mL would be incompatible with your hormone and fertility profile for several reasons:

• Testicular volumes below 12 mL are definitively considered atrophic and strongly correlate with impaired spermatogenesis, reduced total sperm count, and decreased sperm concentration. 1
• Men with true testicular atrophy typically present with elevated FSH (>7.6 IU/L, often much higher), yet your FSH of 9.5 IU/L is only mildly elevated and within the normal reference range of 1–12.4 IU/L. 1, 2
• A sperm concentration of 46 million/mL far exceeds the WHO lower reference limit of 16 million/mL, which is inconsistent with severe bilateral testicular atrophy. 2
• True biological change in testicular size over 4 weeks is extremely unlikely in adults unless there is acute pathology such as torsion, infection, or trauma. 1

Request a Repeat Ultrasound with Proper Technique

You should obtain a repeat scrotal ultrasound with explicit instructions to the sonographer to use high-frequency probes (>10 MHz) and measure three perpendicular dimensions (length, width, height) on axial slices, then calculate volume using the Lambert formula: Length × Width × Height × 0.71. 1 The traditional ellipsoid formula (0.52 coefficient) systematically underestimates testicular volume by 20–30% and should not be used for clinical decision-making. 1

Common technical pitfalls that lead to underestimation include:

• Measuring width on a non-maximal axial slice (the most common error). 1
• Placing calipers at the edge of the tunica albuginea rather than at the true outer border of testicular parenchyma. 1
• Using the wrong formula coefficient (0.52 instead of 0.71). 1

Your Subclinical Varicocele is Unlikely to Cause Atrophy

Subclinical varicoceles detected only on ultrasound do not require treatment and are not associated with clinically significant testicular damage. 3 Only palpable (clinical) varicoceles—grade 2 or 3 on standing examination—are associated with progressive testicular dysfunction and warrant consideration for repair. 1, 4

The evidence on varicocele and hormonal changes shows:

• Varicocele is associated with higher FSH and LH levels and lower inhibin B, but these changes are most pronounced in men with palpable varicoceles and abnormal semen parameters. 4, 5
• In a large European study of 7,035 young men, even grade 1 varicoceles were associated with poorer semen quality, but your sperm concentration of 46 million/mL argues against clinically significant varicocele-related damage. 5
• Varicocelectomy improves testosterone levels primarily in hypogonadal men (testosterone <280 ng/dL or ~10 nmol/L), but your testosterone of 30 nmol/L is well above this threshold. 6

Your subclinical varicocele does not explain the ultrasound finding of 9 mL testes, and treatment is not indicated given your normal fertility parameters. 1, 3

What Your Normal Parameters Tell Us

Your hormone and semen profile is reassuring:

• Testosterone 30 nmol/L is in the high-normal range (normal reference ~10–30 nmol/L), making primary testicular failure extremely unlikely. 2
• FSH 9.5 IU/L is mildly elevated but within the normal reference range (1–12.4 IU/L). FSH >7.6 IU/L suggests some degree of testicular stress, but your level is far below the FSH >35 IU/L threshold that indicates primary testicular failure. 2
• Sperm concentration 46 million/mL is nearly three times the WHO lower reference limit of 16 million/mL, confirming normal spermatogenesis. 2

The combination of mildly elevated FSH with normal testosterone and excellent sperm production indicates reduced testicular reserve—meaning your testes are working harder to maintain normal output—but this does not equate to atrophy. 1, 2

Possible Explanations for Perceived Shrinkage

If you genuinely perceive testicular shrinkage, consider these reversible causes:

• Weight gain or increased scrotal fat can make the testes appear smaller relative to the scrotum. 1
• Cremasteric reflex hyperactivity can cause the testes to retract higher into the scrotum, making them feel smaller. 7
• Comparison bias: Many men overestimate their baseline testicular size, and normal age-related changes in scrotal skin laxity can alter the perceived size. 1

What You Should Do Next

1. Obtain a repeat scrotal ultrasound with explicit instructions to use the Lambert formula (0.71 coefficient) and measure on maximal axial slices. 1
2. Measure LH and calculate free testosterone (using SHBG) to fully characterize your hypothalamic-pituitary-testicular axis. 1, 2
3. Repeat semen analysis in 3–6 months to confirm stability of your sperm parameters, as single analyses can be misleading due to natural variability. 1, 2
4. Avoid exogenous testosterone or anabolic steroids completely, as these will suppress FSH and LH through negative feedback, causing azoospermia that can take months to years to recover. 2

When to Worry

Urgent urology referral is indicated if you develop:

• A palpable testicular mass. 1
• Rapid testicular atrophy (confirmed on repeat ultrasound with proper technique). 1
• Severe oligospermia (<5 million/mL) on repeat semen analysis. 1

Your current profile—normal testosterone, normal sperm count, mildly elevated FSH, and subclinical varicocele—does not warrant urgent intervention, but the ultrasound measurement of 9 mL bilaterally is almost certainly incorrect and should be repeated with proper technique. 1