A Descended Testis in a Baby is Located Externally in the Scrotum
A descended testis is positioned externally within the scrotum—this is the normal anatomical location after complete testicular migration. 1
Normal Testicular Descent Process
During fetal development, testicular descent occurs in two distinct phases:
- Trans-abdominal phase: Occurs during the first trimester, with testes reaching the internal inguinal ring by approximately 22-25 weeks of gestational age 1
- Inguinoscrotal phase: The androgen-dependent migration through the inguinal canal into the scrotum occurs between 25-30 weeks of gestation 1
The most intense testicular migration through the inguinal canal happens between 20-26 weeks postconception, and this is a rapid process observed in only about 13% of fetuses at any given time 2. By 30 weeks postconception, all normally developing testes should be located in the scrotum 3.
Clinical Implications for Newborns
Full-term infants:
- 1-4.6% have undescended testes at birth 4
- Spontaneous descent may occur during the first 6 months of life but is unlikely after this period 1
Premature infants:
- 15-45% have undescended testes at birth due to incomplete gestational development 4, 1
- The prevalence approaches 100% in infants weighing less than 900g 1
- Spontaneous descent is more likely during the first 6 months (corrected for gestational age) 1
Key Distinction: Descended vs. Undescended
Descended testis = External scrotal position
- This is the normal, expected location
- The testis is palpable within the scrotum
- No intervention required
Undescended testis (UDT) = Internal/non-scrotal position
- May be located in the abdomen, inguinal canal, superficial inguinal pouch, or upper scrotum 1
- Approximately 70% of UDTs are palpable; 30% are non-palpable 1
- For non-palpable testes: 55% are intra-abdominal, 30% in the inguinal-scrotal area, and 15% are absent/vanishing 1
Critical Management Point
Any testis not in the scrotum by 6 months of corrected gestational age requires surgical referral 4, 1. Treatment should be completed by 12 months of age (18 months at the absolute latest) because histological damage—including progressive loss of germ cells and Leydig cells—is already evident by this age 4. This timing is critical for preserving fertility potential and reducing (though not eliminating) testicular cancer risk.
Common Pitfall to Avoid:
Do not confuse a retractile testis (which can be manually manipulated into the scrotum and remains there temporarily) with an undescended testis. Retractile testes are managed conservatively, while true undescended testes require surgical intervention 5, 6.