Testicular Atrophy and Sperm Count
Men with testicular atrophy typically have severely reduced sperm counts ranging from azoospermia (0 sperm/mL) to severe oligospermia (<5 million/mL), with approximately 30% retaining some sperm production despite marked testicular dysfunction. 1, 2
Understanding the Clinical Picture
When testicular atrophy is present—defined as testicular volume <12 mL—the underlying pathophysiology usually indicates spermatogenic failure, particularly when accompanied by elevated FSH levels above 7.6 IU/L. 1, 3 This hormonal pattern reflects the pituitary's compensatory response to impaired testicular function, attempting to stimulate failing spermatogenesis.
The relationship between testicular atrophy and sperm production follows a predictable pattern:
Testicular atrophy with FSH >7.6 IU/L strongly suggests non-obstructive azoospermia, meaning complete absence of sperm in the ejaculate due to spermatogenic failure rather than obstruction. 1, 4
Mean testicular size strongly correlates with total sperm count and sperm concentration, so smaller testes produce fewer sperm. 5
Bilateral testicular hypotrophy (<14 mL) predicts severe impairment with total motile sperm counts <20 million, representing an 8.8-fold increased risk compared to normal-sized testes. 6
Sperm Recovery Potential Despite Atrophy
A critical clinical insight challenges the assumption that testicular atrophy means absolute sterility:
Approximately 30% of men with azoospermia, testicular atrophy, and markedly elevated FSH (≥3 times normal) still have retrievable sperm on testicular biopsy. 2 This finding revolutionized fertility treatment, as even minimal sperm recovery enables intracytoplasmic sperm injection (ICSI).
The histopathological patterns determine sperm presence:
Severe hypospermatogenesis is the most common finding when sperm are present despite atrophy and elevated FSH. 2
Sertoli cell-only pattern or complete tubular sclerosis typically indicates no sperm recovery potential. 2, 7
Maturation arrest shows variable outcomes, with sperm recovery in approximately 50% of cases. 7
Diagnostic Algorithm for Atrophic Testes
When evaluating a patient with suspected testicular atrophy:
Confirm azoospermia with centrifuged semen analysis performed at least twice, as the laboratory must examine the pellet under wet mount microscopy for rare sperm. 1
Measure testicular volume using Prader orchidometer (volumes <12 mL confirm atrophy). 3, 5
Obtain hormonal evaluation: FSH, LH, and testosterone. FSH >7.6 IU/L with atrophic testes indicates spermatogenic failure. 1, 3
Perform genetic testing when sperm concentration is <5 million/mL with elevated FSH and testicular atrophy: karyotype analysis (to exclude Klinefelter syndrome 47,XXY) and Y-chromosome microdeletion testing. 1, 3
Consider microsurgical testicular sperm extraction (micro-TESE) if fertility is desired, as this achieves sperm retrieval in 40-50% of non-obstructive azoospermia cases despite elevated FSH. 3, 4 Micro-TESE is 1.5 times more successful than conventional techniques. 1, 3
Critical Caveats
FSH levels alone cannot definitively predict sperm retrieval success—up to 50% of men with non-obstructive azoospermia and elevated FSH have retrievable sperm. 3, 4 This means testicular biopsy or micro-TESE should be offered to couples pursuing assisted reproduction, even with severely elevated FSH.
Testicular histopathology is the most accurate predictor of sperm recovery (accuracy 0.87), far superior to FSH levels, testicular volume, or semen analysis alone. 7
Complete AZFa or AZFb Y-chromosome microdeletions indicate almost zero likelihood of sperm retrieval and contraindicate testicular sperm extraction. 4
Long-Term Monitoring Considerations
Men with testicular atrophy require surveillance beyond fertility concerns:
**Testicular volumes <12 mL carry increased risk of testicular cancer**, particularly intratubular germ cell neoplasia, with >34% risk in the contralateral testis if cancer develops. 3, 5
Regular testicular self-examination should be taught to all men with atrophic testes. 3
Testosterone deficiency may worsen after micro-TESE, potentially requiring testosterone replacement once fertility goals are abandoned. 4