Management of Constitutional Small Testes (Microorchidism)

Initial Assessment and Testicular Volume Measurement

The European Association of Urology recommends measuring testicular volume using a Prader orchidometer as the primary assessment tool, which is cost-effective and correlates well with ultrasound measurements 1
Testicular atrophy/microorchidism is defined as testicular volume <12 ml or a size difference >2 ml (or >20%) compared to the contralateral testis, according to the European Urology guidelines 2
Scrotal ultrasound should be performed selectively in cases where physical examination is difficult or unreliable, including large hydrocele, thickened scrotal skin, epididymal enlargement disproportionate to testicular volume, or when testicular architecture assessment is needed, as recommended by the European Urology guidelines 1, 3

Comprehensive hormonal testing, including total testosterone, LH, FSH, and inhibin B, should be obtained to assess both Leydig cell and Sertoli cell function, according to the European Urology guidelines 4
Semen analysis should be ordered in men of reproductive age to evaluate fertility potential, as recommended by the European Urology guidelines 1
Anti-müllerian hormone (AMH) measurement may be considered as an additional marker of Sertoli cell function, particularly if bilateral small testes raise concern for testicular dysgenesis, according to The Journal of Urology guidelines 5, 6

Men with small testes (<12 ml) and infertility have significantly elevated testicular cancer risk, with a pooled OR of 1.91 for infertile men and a hazard ratio of 11.9 for oligozoospermic men, according to the European Urology guidelines 3
Testicular biopsy should be performed to exclude germ cell neoplasia in situ (GCNIS) in high-risk patients, specifically those with history of cryptorchidism, bilateral testicular microcalcifications, atrophic testes (<12 ml), or infertility, as recommended by the European Urology guidelines 7, 2
Patients with small testes should be counseled to perform regular testicular self-examinations for early cancer detection, regardless of other risk factors, according to the European Urology guidelines 7, 2

Men with unilateral small testis from cryptorchidism and normal contralateral function should be offered orchidectomy due to 3.6-7.4 times higher cancer risk, as recommended by the European Urology guidelines 7, 2
For bilateral small testes with impaired hormonal function or fertility, orchiopexy may be considered if technically feasible, with mandatory biopsy for GCNIS, according to the European Urology guidelines 7, 3
Paternity rates are near-normal with unilateral cryptorchidism but reduced to 35-53% with bilateral cryptorchidism, according to the European Urology guidelines 3

Ultrasound screening should not be routinely performed in all men with small testes, as this may lead to overdiagnosis of incidental findings requiring unnecessary surveillance, according to the European Urology guidelines 1, 3
Ultrasound should be reserved for assessment of testicular architecture, tumor detection in high-risk patients, or when physical examination is inadequate, as recommended by the European Urology guidelines 1, 3
Ultrasound should not be used as a screening tool in isolation, but rather in combination with clinical context, hormonal evaluation, and cancer risk assessment, according to The Journal of Urology guidelines 5, 6

Regular follow-up should be established with monitoring of testicular volume changes, hormonal function, and development of masses, according to the European Urology guidelines 2, 4
Patients should be screened for hypogonadism symptoms, including decreased libido, erectile dysfunction, fatigue, and loss of muscle mass, as recommended by the European Urology guidelines 4
Comprehensive counseling should be provided regarding increased infertility risk, elevated testicular cancer risk, and importance of self-examination, according to the European Urology guidelines 7, 3, 2

Bilateral small testes should not be dismissed without hormonal evaluation and consideration of disorders of sex development, particularly in young males, according to The Journal of Urology guidelines 5, 6
Cancer risk assessment should not be delayed in men with small testes and infertility, as this population requires proactive surveillance, according to the European Urology guidelines 3
Hormonal therapy (GnRH or hCG) should not be used to increase testicular size in adults, as evidence demonstrates poor success rates, according to the European Urology guidelines 1, 3
Testicular biopsy, serial ultrasounds, or tumor markers should not be performed in isolated testicular microcalcifications without additional risk factors, as recommended by the European Urology guidelines 7