Normal Testis Size on Ultrasound: Key Dimensions
The testis is the primary male gonad responsible for spermatogenesis and androgen production. Accurate sonographic measurement of testicular dimensions is essential for evaluating conditions such as atrophy, hypertrophy, and underlying endocrine or oncologic disorders.
Normal Reference Values
| Measurement |
|---|
| 4-5 x 2-3 x 2-2.5 cm |
Clinical Significance
Normal adult testicular dimensions on ultrasound measure approximately 4–5 cm in length, 2–3 cm in width, and 2–2.5 cm in depth. Significant asymmetry between testes—or measurements falling outside these ranges—warrants further clinical correlation.
Testicular atrophy, defined by reduced volume and altered echogenicity, may result from prior orchitis, varicocele, torsion, or hormonal insufficiency. Conversely, diffuse enlargement can be seen with orchitis, lymphoma, or leukemic infiltration. A focal size discrepancy within an otherwise normal testis may indicate a mass requiring further evaluation.
- Testicular atrophy: post-torsion, post-orchitis, varicocele-related, hypogonadism
- Diffuse enlargement: acute orchitis, lymphoma, leukemic infiltration
- Asymmetric enlargement: germ cell tumor, epidermoid cyst
- Bilateral small testes: Klinefelter syndrome, primary hypogonadism
- Bilateral large testes: adrenal rest tumors (congenital adrenal hyperplasia)
Reference: Middleton WD, Kurtz AB. Ultrasound: The Requisites. Mosby. p. 152 (2004)
Imaging Notes
High-frequency grayscale ultrasound (10–15 MHz) is the modality of choice for testicular evaluation. Standard measurements are obtained in three orthogonal planes: longitudinal (length), transverse (width), and anteroposterior (depth). Length is measured on the longitudinal view from superior to inferior pole; width and depth are obtained on the transverse view. Testicular volume can be estimated using the ellipsoid formula: length × width × depth × 0.523, with normal adult volume typically ranging from 12–20 mL.
Ensure the patient is supine with the scrotum supported. Compare both testes symmetrically and document echogenicity alongside dimensions. Color Doppler should be added to assess vascularity, particularly when size asymmetry or altered echogenicity is present.