At what age should testicular descent be completed in a healthy infant?

Normal Testicular Descent Timeline

Testicles normally descend into the scrotum between 25-30 weeks of gestational age, with spontaneous descent possible in the first six months of life but unlikely after six months of corrected age. 1

Gestational Development

The process of testicular descent occurs in two distinct phases:

• Transabdominal phase occurs during the first trimester (8-15 weeks of gestation), controlled by gubernacular enlargement and cranial ligament regression 2
• Inguinoscrotal phase occurs between 25-30 weeks of gestation and is androgen-dependent 1, 2
• At approximately 22-25 weeks of gestational age, the testes are positioned at the internal ring 1

Prevalence at Birth

The likelihood of undescended testes at birth varies dramatically with gestational age and birth weight:

• 1-3% of full-term male infants have undescended testes at birth 1, 3
• 15-30% of premature male infants have undescended testes at birth 1
• Nearly 100% of extremely low birth weight infants (<900g) have undescended testes at birth 1
• Prevalence decreases as birth weight increases, reaching approximately 3% in infants weighing 2,700-3,600g 1

Postnatal Spontaneous Descent

The critical window for spontaneous descent is the first 6 months of life (corrected for gestational age):

• Spontaneous descent may occur in up to 70% of cases during the first 3-6 months of life 4
• After 6 months of corrected age, testes that remain undescended are unlikely to descend spontaneously 1, 3
• In full-term infants, no spontaneous descent occurs after 4 months of age 4
• In premature infants, spontaneous descent may occur up to 6 months of corrected age 4
• The incidence decreases from 4.5% at birth to approximately 1-2% by 6-12 months of age 3, 5

Clinical Action Points

Primary care providers should:

• Palpate testes for quality and position at each well-child visit 1
• Refer to a surgical specialist by 6 months of corrected age if testes remain undescended 1, 3
• The rationale for referral at 6 months is the low probability of spontaneous descent after this age and the potential for continued testicular damage 1

Emergency Situations

Bilateral nonpalpable testes in a newborn male require immediate specialist consultation to evaluate for possible disorders of sex development, particularly life-threatening congenital adrenal hyperplasia 1

Common Pitfall

The most critical error is delaying referral beyond 6 months of age, as germ cell damage begins after 15-18 months, with progressive fertility loss occurring if orchidopexy is not performed by 18 months 1, 6