Aquired undescended testicles

Traditionally it’s been believed that boys born with both testes fully descended aren’t at risk of developing undescended testicles. So when a undescended testicle (UDT) is found in an older boy it’s been blamed on observer error, misdiagnosis of retractile testes, or late referral. However, many parents of older boys with UDT insist that the testes were in the scrotum when the boy was an infant.

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This has become noticeable as orchiopexy is done at a younger age. Since the 1940s, this age has been steadily falling from post-puberty to the age of 10–12 years in the 1950s, to 2–3 years in the late 1970s and to 6 months to 1 year nowadays. The age at surgery became grouped around two ages: 2–3 years old and 10–12 years old, which previously wouldn’t have been noticeable.

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Orchidopexy rates have been reported to be as high as 2–3% in all boys up to 14–17 years of age, despite the estimated 0.8–1.0% incidence rate of congenital UDT. At birth, UDT-rates are higher than at 3 months or 1 year of age. Yet a considerable number of boys undergo an operation well above the recommended age.

Why do testes ascend and become cryptorchoid?

A theoretical model is shown in the diagram below. Around birth, the testis descends to a low position at the bottom of the scrotum with an adequate length of the spermatic cord. However, if the cord is too short, but just long enough to allow a low-scrotal position, the testis seems descended while it is in fact undescended. As the boy grows, inadequate lengthening will result in a high-scrotal position at the age of 3–6 years and in an inguinal position at the age of 7–12 years. At puberty, most testes will re-descend via a high-scrotal position to a low-scrotal position. The concept of UDT is therefore not static, but dynamic. The testicle can behave like a yo-yo and only reach its final position at early puberty. Being retractile contributes to this effect.


Research in 1964 found there is a relatively large group of boys with a shorter than normal cord whose testes are late descenders (descended in the first 3 months after birth). Recent studies in Oxford and Cambridge noted that late descenders evolve into early ascenders.

Between 2% and 45% of retractile testes are reported to become an acquired UDT. In a study at Southampton General Hospital, the ascended testis had been documented on at least one occasion as descended in 67% (24 children), or retractile in 28% (10 children).

It is important to distinguish clearly between an “ascended” and a “retractile” testis. They are not the same, because an ascended testis cannot be brought into the normal scrotal position, i.e. it is a true undescended testis.
On the other hand, a “retractile” testis can be brought to lie in a normal scrotal position. The possibility of a “retractile” testis becoming an “ascended” testis is not in con-flict with this defined difference.
Source: Fenton 1990

So all the research points to there being congenital differences with the structure of testicles that become ascended. In some ways they aren’t that different from undescended testicles a child is born with, except they manifest later.

Yet there are differences. The epididdimus has around three times more abnormalities in congenital UDTs than in acquired UDT (source), and the structures in the groin are found to be in a different state during surgery (congenital UDTs have a wide open processus vaginalis).

They’re also in different places. Compared with an undescended testicle you’re born with, an acquired undescended testicle is normally located at the scrotal entrance or in the superficial inguinal pouch an can often be manipulated into an unstable scrotal position.

Is surgery ncessary?

It is still controversial whether acquired UDT can be best managed by pre-pubertal orchidopexy or by a ‘wait and see’ policy. As a result of pubertal testosterone production, the testis will drop spontaneously in three of four cases (I didn’t note the journal article I’m quoting from – sorry).

In this 10 year old boy, the testicles have potentially re-ascended into the groin (due to their size) and surgery is about to be performed to bring them down to the scrotum

Recent evidence suggests that unlike normal undescended testicles (congenital UDT) the malignancy rate in acquired UDT is comparable to the normal population. After natural descent, there is no increased risk of testicular cancer.

Testicular biopsies of acquired UDT show the same less pronounced cell degredation than in biopsies of congenital UDT. It isn’t known how they’ll affect fertility, or whether surgery will improve or exacerbate these abnormalities. This will also depend on how the testis is fixed in the scrotum. It’s been shown that there is less spermatogenic damage after spontaneous descent than after orchidopexy.

What about younger children?

The above all makes sense if the testicle was present but disappears when the boy is aged 3-5, or later on. But what about when it’s there and not within a matter of months?

In Cambridge, UK, 742 boys were examined at birth and the position of their testicles recorded. They were then re-examined at 3, 12, 18 and 24 months old.

A staggering 5.9% of these boys had at least one undescended testicle when born (not as bad as 9% in Denmark, but much worse than previously measured in the UK). This fell to 2.4% at 3 months, showing it’s worth waiting before performing surgery – and then rose to a shocking 6.7% with an undescended testicle at 12 months!

This is the first study to show that “acquired cryptorchidism” or ascending testicles is common, with a cumulative incidence of 7% by 24 months.

Further evidence comes from research in Oxford, UK, where they found that 40% of boys whose testicles were undescended at birth but had done so by 3 months had reascended again by the age of 12 months.

Doesn’t make much sense does it, as we don’t carry out surgery on 7% of infants!


What should you do? What should your surgeon do?

Hack’s research suggests for older children:

  • If your son has bilateral (two) acquired undescended testicles, operate now
  • If your son has unilateral (one) acquired undescended testicle, wait and see what happens at puberty, because over 50% of acquired UDT descend spontaneously.
    • Though others say spontaneous descent during follow-up of children with acquired UDT is expected in 57–71% of patients (Sijstermans et al., 2006; Eijsbouts et al., 2007).

If your son is under 2, my suggestion is don’t wait; have the surgery performed. I am not a medic so this is not medical advice, but it makes sense to me after reading the literature.

Further reading: