Most Likely Cause of Painless Testicular Atrophy in Adult Males
The most likely cause of painless testicular atrophy in an adult male is varicocele, which is present in approximately 15% of the normal male population and causes testicular dysfunction through increased scrotal temperature, hypoxia, and reflux of toxic metabolites. 1
Primary Etiology: Varicocele
Varicocele is the leading reversible cause of testicular atrophy in adults, particularly when painless. 1 The condition results from abnormal dilation of the pampiniform venous plexus and can cause progressive testicular damage over time. 2, 3
Key characteristics include:
- Varicoceles are found in 25% of men with abnormal semen analysis and 35-40% of men presenting with infertility 1
- The condition causes testicular atrophy through multiple mechanisms: elevated testicular temperature, tissue hypoxia, and reflux of adrenal metabolites 1, 4
- Testicular volume loss occurs even in fertile men with varicoceles, though the degree of atrophy does not reliably predict fertility status 5
Secondary Causes to Consider
Hypogonadism and Endocrine Dysfunction
Testicular atrophy with elevated FSH levels (>7.6 IU/L) suggests primary testicular failure (non-obstructive azoospermia), while normal FSH suggests obstructive causes. 1 This distinction is critical for determining the underlying pathophysiology.
Genetic Abnormalities
Karyotype abnormalities, particularly Klinefelter syndrome (47,XXY), should be considered in men with testicular atrophy, especially when accompanied by elevated FSH or sperm concentration <5 million/mL. 1 These chromosomal abnormalities represent the most common known genetic causes of male infertility with associated testicular atrophy.
History of Testicular Cancer
Survivors of testicular cancer have increased risk of hypogonadism and testicular atrophy, with the greatest risk occurring 6-12 months after treatment. 1 However, some recovery of Leydig cell function may occur over time.
Post-Surgical Complications
Testicular atrophy can occur as a sequela of inguinal hernioplasty due to thrombosis of spermatic cord veins from surgical trauma. 6 This is an important consideration in patients with prior inguinal surgery.
Diagnostic Approach
The initial evaluation should include:
- Physical examination to detect varicocele (present in 15% of normal males), assess testicular size asymmetry, and evaluate for masses 1
- Scrotal ultrasound with Doppler to identify varicocele (dilated veins >3mm), assess testicular parenchyma, and exclude other pathology 4
- Hormonal evaluation including FSH and testosterone levels to distinguish primary testicular failure from obstructive causes 1
- Karyotype testing if FSH is elevated, testicular atrophy is present, or sperm concentration is severely reduced (<5 million/mL) 1
Critical Clinical Pitfalls
Do not assume painless testicular atrophy is benign without proper evaluation. 1 While varicocele is the most common cause, other serious conditions including testicular cancer, Klinefelter syndrome, and primary hypogonadism must be excluded through appropriate testing.
Testicular microcalcifications on ultrasound warrant additional attention. 1 In men with testicular atrophy and microcalcifications, the risk of testicular cancer is significantly elevated (18-fold higher odds in infertile men), and testicular biopsy may be indicated to exclude germ cell neoplasia in situ.
The degree of testicular volume loss does not reliably predict fertility status in varicocele patients. 5 Even men with significant testicular atrophy from varicocele may remain fertile, so treatment decisions should be based on comprehensive evaluation including semen analysis rather than testicular size alone.