Normal Testicular Volume Size on Ultrasound
The testis is the primary male gonad responsible for spermatogenesis and androgen production. Accurate sonographic measurement of testicular volume is essential for evaluating gonadal development, fertility concerns, and suspected pathology such as atrophy or mass effect.
Normal Reference Values
| Measurement |
|---|
| <15-20 mL |
Clinical Significance
Normal adult testicular volume is accepted as less than 15–20 mL per testis on ultrasound. Volumes below the lower end of the normal range suggest testicular atrophy, which may be associated with impaired spermatogenesis, hypogonadism, prior orchitis, varicocele, or cryptorchidism. Bilateral small testes are a key sonographic correlate of primary testicular failure.
Conversely, asymmetric enlargement or a volume disproportionate to age should raise concern for an underlying mass, orchitis, or torsion with reactive change. In the pediatric population, testicular volume assessment is valuable for staging puberty and diagnosing precocious or delayed development. A key pitfall is mistaking peritesticular fluid (hydrocele) for parenchymal volume — only the echogenic testicular parenchyma should be included in the measurement.
- Testicular atrophy (post-orchitis, varicocele, cryptorchidism)
- Primary hypogonadism / Klinefelter syndrome
- Testicular torsion with ischemic atrophy
- Orchitis causing acute enlargement
- Intratesticular mass with volume asymmetry
Reference: Middleton WD, Kurtz AB. Ultrasound: The Requisites. Mosby. p. 152 (2004)
Imaging Notes
Testicular volume is calculated sonographically using the prolate ellipsoid formula: Volume = Length × Width × Height × 0.523. All three orthogonal dimensions should be obtained in the same scanning plane, measuring only the testicular parenchyma and excluding the epididymis and any surrounding fluid. A high-frequency linear transducer (10–15 MHz) is standard, providing optimal resolution of the homogeneous, medium-echogenicity testicular parenchyma.
Both testes should be measured and compared, as a volume discrepancy of more than 20% between sides may be clinically significant even when absolute values remain within normal limits. Ensure the patient is supine with the scrotum supported; gentle transducer pressure avoids compression artifact that could artificially reduce measured dimensions.