What can cause rapid testicular atrophy in a patient with unknown cause and no prior medical history?

Causes of Rapid Testicular Atrophy

Most Critical Immediate Concern: Testicular Torsion

If you are experiencing rapid testicular atrophy with acute pain, testicular torsion is a surgical emergency requiring immediate evaluation within 6-8 hours to prevent permanent testicular loss. 1, 2

Acute Vascular Causes (Hours to Days)

• Testicular torsion causes rapid atrophy through twisting of the spermatic cord and compromising blood flow, with testicular salvage rates becoming dismal when symptoms exceed 24 hours 1, 3, 4, 2
• Even when surgically salvaged, 54% of patients develop testicular atrophy within 12.5 months, particularly when pain duration exceeds 1 day (91% atrophy rate) 2
• Blunt scrotal trauma causes testicular atrophy in 50% of cases through vascular compromise and tissue damage, with atrophy developing over months following injury 5
• Post-surgical vascular injury from inguinal hernia repair causes atrophy through thrombosis of spermatic cord veins from surgical dissection trauma 6

Infectious/Inflammatory Causes (Days to Weeks)

• Epididymoorchitis leads to progressive inflammation and testicular damage, presenting with testicular discomfort, swelling, and tenderness that may initially mimic other conditions 1, 3
• Persistent tenderness, swelling, or palpable abnormality after antibiotic trial warrants urgent ultrasound evaluation 1

Hormonal Causes (Weeks to Months)

• Exogenous testosterone or anabolic steroid use causes reversible testicular atrophy through suppression of FSH and LH via negative feedback, with immediate discontinuation recommended if fertility is desired 7, 8
• Estrogen therapy leads to marked testicular atrophy with reduced spermatogenesis after only 21 days, with progressive changes including paucity of germ cells and Leydig cell reduction after prolonged use 9

Malignancy (Variable Timeline)

• Testicular cancer can present with testicular discomfort or swelling, though a painless solid testicular mass is pathognomonic 1
• Men with testicular atrophy (<12 mL) have significantly increased risk of testicular germ cell tumors and should perform regular self-examination 1, 7

Essential Immediate Evaluation

Physical Examination Priorities

• Assess for acute surgical emergency: sudden onset severe pain, abnormal testicular lie, absent cremasteric reflex, or "blue dot sign" indicating appendage torsion 1
• Measure testicular volume using Prader orchidometer—volumes <12 mL indicate atrophy and require further workup 1, 7, 3
• Evaluate for varicocele on standing examination, present in 35-40% of infertile men and associated with progressive testicular damage 1, 3

Urgent Imaging

• Scrotal ultrasound with Doppler is the first-line imaging modality to assess testicular perfusion, identify masses, and measure testicular volume accurately 1, 7
• Heterogeneous echogenicity on ultrasound predicts testicular atrophy and indicates significant parenchymal damage 2

Laboratory Evaluation

• Measure serum FSH, LH, and total testosterone on morning samples to distinguish primary testicular failure (elevated FSH >7.6 IU/L with low testosterone) from secondary causes 1, 7, 8
• Obtain tumor markers (β-HCG, AFP, LDH) if testicular mass is identified, as elevated values guide diagnosis and staging 1

Critical Pitfalls to Avoid

• Never delay surgical exploration if testicular torsion is suspected—waiting for imaging can result in irreversible testicular loss within 6-8 hours 1, 2
• Do not start testosterone therapy if the cause is unclear, as exogenous testosterone will worsen atrophy and cause azoospermia through negative feedback 7, 8
• Do not dismiss trauma history—even seemingly minor scrotal trauma causes atrophy in 50% of cases over subsequent months 5

When Fertility Preservation is Critical

• Bank sperm immediately (2-3 separate collections) if any sperm are present in ejaculate before further decline occurs, as once azoospermia develops, even microsurgical extraction only achieves 40-50% retrieval rates 7, 8
• This is particularly urgent if you have history of cryptorchidism, prior testicular surgery, or are taking medications that suppress the hypothalamic-pituitary-gonadal axis 1, 7