Is a testicle volume of 3.5 x 2.8 x 2, calculated using the 0.71 formula, within the normal range for an adult male?

Testicular Volume Assessment

Your calculated testicular volume of approximately 9.8 mL (using 3.5 × 2.8 × 2 cm with the 0.71 formula) is below the normal adult range and warrants clinical evaluation, as volumes <12 mL are considered small or atrophic and associated with impaired spermatogenesis. 1

Understanding Your Measurement

Using the Lambert equation (Length × Width × Height × 0.71), your dimensions yield approximately 9.8 mL. However, the accuracy of this calculation depends critically on:

• Measurement method: Clinical measurements with a ruler typically overestimate ultrasound volumes by 70-80% in adults due to inclusion of scrotal skin and epididymis 2
• Formula selection: For smaller testes (<18 mL), research suggests the Hansen formula (L × W² × 0.59) may be more accurate than the Lambert equation when using clinical measurements 3
• Gold standard: Ultrasound measurements provide the highest accuracy and reproducibility for testicular volume quantification 2, 3

Clinical Significance of Small Testicular Volume

Testicular volume <12 mL indicates:

• Impaired spermatogenesis risk: The American Urological Association identifies this threshold as associated with reduced sperm production 1
• Need for fertility assessment: Testicular size directly predicts sperm production capacity 1
• Potential underlying pathology: Even with normal hormone levels, small testes may indicate varicocele, history of cryptorchidism, or other conditions 1

Recommended Diagnostic Workup

Immediate next steps should include:

• Semen analysis: Obtain at least two analyses separated by 2-3 months, as this is the most direct assessment of testicular function 1
• Complete hormonal panel: Measure FSH, LH, total testosterone, SHBG, and prolactin—FSH is most important as it correlates strongest with testicular size and function 1
  • Critical threshold: FSH >7.6 IU/L indicates testicular dysfunction even within laboratory reference ranges, with 5-13 fold higher risk of abnormal sperm concentration 1
• Scrotal ultrasound: Obtain precise volume measurement and assess for structural abnormalities, varicocele, or non-homogeneous architecture 1

If initial testing reveals abnormalities:

• Karyotype analysis and Y-chromosome microdeletion testing: Recommended when testicular volume <12 mL or sperm concentration is abnormal 1
• Varicocele evaluation: Can cause small testes with normal hormones; correction may improve both size and fertility 1
• Cryptorchidism history: Even after successful orchidopexy, can result in persistently small testes with reduced function 1

Special Cancer Risk Consideration

If you have history of cryptorchidism:

• Men with testicular volume <12 mL and cryptorchidism history carry >34% risk of intratubular germ cell neoplasia in the contralateral testis, particularly under age 30 1
• Testicular biopsy should be considered in this specific population 1

Measurement Accuracy Considerations

Your clinical measurement likely overestimates actual testicular volume:

• Ultrasound volumes are typically 0.8-1.0 mL smaller than clinical measurements using the 0.71 formula for testes in this size range 3
• If your clinical measurement yields 9.8 mL, actual ultrasound volume may be closer to 8-9 mL 3
• This makes the clinical significance even more pronounced, as you may be further below the 12 mL threshold 3

Common pitfall: Relying solely on clinical measurements without ultrasound confirmation can lead to underestimation of the severity of testicular hypotrophy, particularly when volumes are borderline 2, 3