Testicle Size Asymmetry in Boys: Normal Variation vs. Testicular Torsion

Slight size difference (up to ~20%) is normal. The left testis often hangs lower and may be slightly larger.

When to Worry

Sudden, significant asymmetry + pain = possible testicular torsion (spermatic cord twist → ischemia).

Torsion Red Flags (Emergency)

• Acute, severe scrotal pain (may radiate to groin/abdomen)
• Swelling, redness, high-riding testis
• Nausea, vomiting
• Absent cremasteric reflex

Time-Critical

• <6 hours: ~90–100% salvage rate.
• 6–12 hours: ~50% salvage.
• >24 hours: Near 0% salvage; orchiectomy likely.

Other Causes of Asymmetry

• Hydrocele, varicocele, hernia, tumor, prior trauma/surgery.

Action

If torsion suspected → ER immediately (ultrasound with Doppler, emergent surgical detorsion + orchiopexy). If painless asymmetry → urology outpatient eval.