Normal Testicular Volume Size by Age on Ultrasound
The testes are paired gonadal structures whose size varies considerably across childhood and adolescence, reflecting hormonal maturation and pubertal development. Accurate sonographic measurement of testicular volume is essential for detecting cryptorchidism, atrophy, torsion sequelae, and precocious or delayed puberty. Ultrasound is the primary imaging modality for testicular assessment due to its high resolution, lack of ionizing radiation, and real-time capability.
Normal Reference Values
| Location | Age | Measurement |
|---|---|---|
| Width | Newborn | 1.0 cm |
| Length | Newborn | 1.5 cm |
| Volume | Newborn | 1.14 mL |
| Width | 1-3 months | 1.2 cm |
| Length | 1-3 months | 2.0 cm |
| Volume | 1-3 months | 2.01 mL |
| Volume | 4-6 months | 1.81 mL |
| Length | 1-10 y/o | 1.6 cm |
| Volume | 1-10 y/o | 1.6 mL |
| Length | 11-12 y/o | 1.9 cm |
| Volume | 11-12 y/o | 2.0 mL |
| Length | 13-16 y/o | 3.5 cm |
| Volume | 13-16 y/o | 13.0 mL |
Clinical Significance
Testicular volume increases minimally during mid-childhood (ages 1–10 years), averaging approximately 1.6 mL, then rises sharply during puberty, reaching 13.0 mL by ages 13–16. A transient physiologic increase is noted in early infancy (1–3 months) due to the neonatal testosterone surge, with volumes reaching 2.01 mL before declining slightly at 4–6 months to 1.81 mL.
Volumes significantly below age-expected norms may indicate testicular atrophy, primary hypogonadism, or post-torsion injury. Bilateral enlargement prior to age 9 raises concern for precocious puberty, whereas failure to enlarge beyond 10–11 years may suggest hypogonadotropic hypogonadism or primary gonadal failure.
- Cryptorchidism: undescended testis typically shows reduced volume
- Testicular torsion sequelae: volume loss on follow-up imaging
- Precocious puberty: volume exceeding age norms before age 9
- Hypogonadotropic hypogonadism: prepubertal volume persisting into adolescence
- Varicocele: asymmetric volume reduction in affected testis
Reference: Cassorla FG, Golden SM, Johnsonbaugh RE et al. Testicular volume during early infancy. J. Pediatr. 1981;99(5):742-3.
Imaging Notes
Testicular volume on ultrasound is calculated using the prolate ellipsoid formula: Volume = Length × Width × Height × 0.523. The transducer should be high-frequency (≥12 MHz) with the patient supine and the scrotum supported. Three orthogonal dimensions are obtained in the longitudinal and transverse planes. Care should be taken to exclude the epididymis from measurements, as inadvertent inclusion overestimates true testicular volume.
In neonates and infants, small probe footprint linear transducers improve contact and image quality. Bilateral measurements should always be obtained and compared, as asymmetry greater than 20% may be clinically significant even when each testis falls within published normal ranges for age.