Can an unknown infection cause testicular atrophy in an asymptomatic adult male?

Testicular Atrophy from Unknown Infection

While infections can theoretically cause testicular atrophy, an asymptomatic presentation makes infection highly unlikely as the cause of progressive testicular shrinkage, and you should urgently pursue alternative diagnoses including testicular torsion, varicocele, hormonal disorders, or malignancy.

Why Infection is Unlikely in Your Case

• Epididymitis/orchitis typically presents with obvious symptoms including pain, swelling, fever, and urinary symptoms—not silent testicular shrinkage 1
• Male accessory gland infections that affect testicular function are symptomatic conditions requiring treatment of both the patient and sexual partners when sexually transmitted 1
• Idiopathic lymphocytic orchitis can cause testicular atrophy but presents with testicular pain, not asymptomatic shrinkage 2

More Likely Causes of Asymptomatic Testicular Atrophy

Testicular Torsion (Including Intermittent/Partial)

• Intermittent testicular torsion can cause progressive atrophy with minimal or resolved symptoms between episodes 3, 4
• Partial torsion may present with less severe or wave-like symptoms that patients dismiss 3
• This is a surgical emergency requiring intervention within 6-8 hours during acute episodes to prevent permanent testicular loss 3, 4

Varicocele

• Varicocele causes testicular atrophy through chronic venous congestion and is often asymptomatic 1
• Testicular size difference >2 mL or 20% warrants surgical intervention 1
• This is the most common correctable cause of male infertility and testicular atrophy 1

Hormonal Disorders

• Testosterone deficiency with elevated FSH (>7.6 IU/L) indicates primary testicular failure causing atrophy 1
• Klinefelter syndrome and other chromosomal abnormalities cause progressive testicular atrophy with elevated FSH and small, firm testes 1
• Hypogonadism can develop insidiously without obvious symptoms beyond gradual testicular shrinkage 1

Prior Trauma or Torsion

• Testicular atrophy occurs in 50% of patients following blunt scrotal trauma, even when initially asymptomatic 5
• Previous testicular torsion, even if spontaneously resolved, commonly causes delayed atrophy through ischemic damage 6

Cryptorchidism History

• Undescended testes have high rates of secondary atrophy, particularly after surgical correction in adulthood 1, 6
• Even successfully corrected cryptorchidism can lead to progressive atrophy years later 6

Critical Immediate Actions Required

Urgent Clinical Evaluation

• Obtain immediate scrotal Duplex Doppler ultrasound to assess testicular blood flow, size, and identify structural abnormalities like varicocele 3, 4, 7
• Measure both testes precisely—size difference >2 mL or 20% is clinically significant 1
• Assess for the "whirlpool sign" indicating torsion or reduced blood flow suggesting chronic ischemia 3, 4

Laboratory Testing

• Measure serum FSH, LH, and total testosterone (early morning, fasting, repeated if abnormal) to identify hormonal causes 1
• FSH >7.6 IU/L with testicular atrophy suggests primary testicular failure 1
• If FSH is elevated with sperm concentration <5 million/mL, obtain karyotype testing to exclude Klinefelter syndrome 1

Physical Examination Findings to Document

• Testicular consistency (firm suggests malignancy or Klinefelter; soft suggests atrophy) 1
• Presence of varicocele (feels like "bag of worms," more prominent when standing) 1
• Epididymal induration or vas deferens abnormalities 1
• Testicular position and mobility 3, 4

Common Pitfalls to Avoid

• Do not assume "no symptoms" means "no emergency"—intermittent torsion and varicocele are often painless but progressive 3, 4
• Do not delay imaging for laboratory results—testicular torsion can present atypically in adults and requires immediate diagnosis 3, 4
• Do not dismiss unilateral atrophy as benign—it may indicate underlying systemic disease, hormonal dysfunction, or malignancy risk 1
• Normal urinalysis does not exclude serious pathology causing testicular atrophy 3, 4

When to Consider Malignancy

• Testicular atrophy increases risk of testicular germ cell tumors, particularly with history of cryptorchidism 1
• Any testicular mass, heterogeneous echotexture, or microcalcifications on ultrasound warrant oncology referral 1
• Testicular cancer is the most common malignancy in men of reproductive age and can present with painless testicular changes 1

Bottom Line

Your asymptomatic testicular shrinkage is almost certainly NOT from an unknown infection. You need urgent urological evaluation with Duplex Doppler ultrasound and hormonal testing to identify the actual cause—most likely varicocele, hormonal disorder, prior unrecognized torsion/trauma, or rarely malignancy. Time-sensitive conditions like intermittent torsion require immediate diagnosis to prevent complete testicular loss.