Definition of Testicular Atrophy
An atrophied testicle is clinically defined as a testis with a volume less than 12 ml, which is associated with potential spermatogenic failure, especially when accompanied by elevated FSH levels. 1
Clinical Assessment of Testicular Atrophy
- Testicular atrophy can be assessed through physical examination using a Prader orchidometer, which provides a good surrogate for volume measured via ultrasound in most cases 2
- Scrotal ultrasound is indicated in selected cases where physical examination is difficult, such as with large hydrocele, inguinal testis, epididymal enlargement/fibrosis, thickened scrotal skin, or when the epididymis is large compared to the total testicular volume 2
- Testicular volume difference of more than 50% compared to the contralateral testis (measured by Prader orchidometer or ultrasound) is considered significant atrophy 3
- The Testicular Atrophy Index (TAI) can be calculated using the formula: [(TV right - TV left)/largest TV] × 100, with a TAI >20% considered clinically significant 4
Causes of Testicular Atrophy
- Testicular atrophy may result from various conditions including:
- Painful events such as mumps-orchitis or testicular trauma 5
- Testicular torsion (with 54% of patients developing atrophy even after salvage procedures) 3
- Cryptorchidism (undescended testis), which may lead to an "incompetent" small testis even after surgical correction 5
- Hormonal treatments, particularly estrogen therapy 6
- Extratesticular diseases such as liver cirrhosis, chronic alcoholism, and hemochromatosis 5
- Certain medications (immunosuppressive drugs, chemotherapy) and radiation exposure 5
- Genetic conditions, with Klinefelter syndrome being the most common chromosomal abnormality associated with testicular atrophy 1, 5
Clinical Significance of Testicular Atrophy
- Atrophic testes (<12 ml) are considered a risk factor for testicular cancer and should be monitored accordingly 2
- Men with testicular atrophy and testicular microcalcification (TM) should be offered testicular biopsy due to increased risk of testicular germ cell tumors 2
- Testicular atrophy is strongly associated with spermatogenic failure, particularly when accompanied by elevated FSH levels above 7.6 IU/L 1
- In cases of unilateral undescended testis, the contralateral normal descended testis may also have structural abnormalities, including smaller volume and softer consistency 2
Monitoring and Management
- Men with atrophic testes should be advised to perform regular testicular self-examination for early detection of testicular cancer 2
- Testicular biopsy should be considered for infertile men with atrophic testes (<12 ml) and testicular microcalcification 2
- For adult men with a unilateral undescended testis and normal hormonal function/spermatogenesis, orchidectomy should be considered 2
- In men with bilateral testicular atrophy and infertility, microsurgical testicular sperm extraction (micro-TESE) may be considered to search for areas of preserved spermatogenesis 1
Important Considerations
- Normal testicular asymmetry exists in healthy adolescents, with approximately 59% having a smaller left testis 4
- About 20% of healthy adolescents meet threshold values currently used in clinical practice (TAI >20% or volume difference >2 ml), highlighting the importance of careful interpretation of these measurements 4
- Duration of pain >1 day and heterogeneous echogenicity on ultrasound are predictive factors for testicular atrophy following testicular torsion 3
- Serial measurements of testicular volume should be performed in cases of suspected atrophy to monitor progression 4