Is a 3.5cm Testicle Normal?
A testicular length of 3.5 cm falls within the normal range for adult men, corresponding to a volume of approximately 12-15 ml, which is at the lower end of normal but not considered atrophic. 1, 2
Normal Testicular Dimensions
- Adult testicular volume typically ranges from 12-20 ml, with volumes below 12 ml generally considered small or atrophic 1, 2
- In healthy Vietnamese men, the mean testicular volume was 13.64 ± 3.44 ml (left: 13.94 ml; right: 13.34 ml), providing a reference for Asian populations 3
- A European study of 444 men found median testicular volumes of 14.1 ml (right) and 13.0 ml (left), with a range of 3.0-35.2 ml 4
- Testicular size of 3.5 cm in length typically corresponds to a volume of 12-15 ml when using standard ellipsoid volume calculations, placing it at the threshold between normal and small 1, 4
Clinical Significance of Testicular Size
Testicular volumes below 12 ml warrant further evaluation, particularly in specific clinical contexts:
- Men with testicular volume <12 ml have a >34% risk of germ cell neoplasia in situ in the contralateral testis if they have testicular cancer 1, 2
- Volumes <12 ml are associated with impaired spermatogenesis and potential fertility issues 1, 2
- Mean testicular size strongly correlates with total sperm count, sperm concentration, and sperm motility 4, 5
- Testicular function becomes significantly impaired in testes smaller than 14 ml, with both sperm quantity and quality affected 5
When to Investigate Further
Consider additional evaluation if the 3.5 cm testis is associated with:
- Age under 40 years with volume <12 ml, as this represents testicular atrophy 1, 6
- History of cryptorchidism (undescended testis), which is associated with smaller testicular volumes and increased cancer risk 1, 2, 4
- Infertility concerns, as smaller testicular size correlates with reduced sperm parameters 3, 5
- Asymmetry between testes, though the right testis is normally slightly larger than the left 3, 4
- Palpable mass, firmness, or pain, which warrant ultrasound evaluation regardless of size 1
Measurement Considerations
- The Prader orchidometer is a cost-effective surrogate for ultrasound volume measurement in routine clinical practice 1, 2
- Ultrasound is recommended when there is large hydrocele, inguinal testis, epididymal enlargement, thickened scrotal skin, or when the epididymis appears large relative to testicular volume 1
- External caliper measurements overestimate testicular dimensions by 5.7 mm (length), 2.9 mm (thickness), and 1.4 mm (width) compared to ultrasound 7
Key Clinical Pitfall
Do not confuse normal testicular size with tumor size thresholds: The 4 cm cutoff mentioned in testicular cancer guidelines refers to tumor dimensions within the testis, not overall testicular size 6. A 3.5 cm testis is not inherently concerning for malignancy based on size alone.