At about the 28th week of gestational age, the testes begin descent through the internal inguinal ring,
ultimately ending up in the scrotum. The left testis starts earlier than the right, and full descent may not
be complete until several months after birth. Adequate amounts of male hormone are necessary for
testicular descent. Inadequate levels of male hormone or poor end- organ response to the hormone can
interrupt this process resulting in an undescended testis (UDT), either unilateral or bilateral .
The UDT can be found anywhere from the level of the kidney in the retroperitoneum to the external
inguinal ring, although it most commonly resides in the inguinal canal. A congenital indirect inguinal
hernia or patent processus vaginalis is associated with the UDT 90% of the time. Occasionally a testis is
totally absent, presumably due to antenatal torsion with resorption.
The incidence of UDT in full-term boys by one year of age is about 0.5%. Premature baby boys have an
incidence 10 times higher. Fifty per cent of UDT occur on the right and 25% on the left, and 25% are
bilateral. This distribution is similar to that of congenital inguinal herniae and reflects the order of
testicular descent.
UDT is diagnosed by physical examination. The examination must be conducted carefully and
compulsively with warm hands in a relaxed cooperative patient so as to distinguish the retractile testis
from the true UDT. Starting at the internal inguinal ring in the upper outer groin, firm downward
pressure is used along the inguinal canal to locate the testis and attempt to push it into the scrotum. If
the testis can be brought down into the scrotum, it is a retractile testis and not an UDT. Such retractile
testes will ultimately end up in the scrotum on their own when endogenous androgenic hormone levels
increase, and operation is not indicated. If a testis cannot be palpated at all, it is likely either intraabdominal or absent.
Indications for operation for UDT include the following:
1.
Enhanced spermatogenesis/fertility:
Above the scrotum, the UDT is subjected to higher body
temperature. Testicular damage is related to the duration of exposure to and the magnitude of the
higher temperature; these two factors correlate to the age at orchiopexy and the level of descent,
respectively. An autoimmune reaction may occur which can also affect the contralateral descended
testis in cases of unilateral UDT. Pathologic changes (eg, decrease in spermatogonia, decrease in tubular
diameter) begin to appear in the second or third year of life. I generally advise operation after one year
of age to allow the testis that might further descend to do so but before age two to avoid testicular
damage. Left uncorrected, 37% to 70% of patients with unilateral and 100% with bilateral UDT are
infertile. With early repair, 95% of boys with unilateral and 70% with bilateral UDT will achieve fertility.
2.
Monitoring for malignancy:
Testicular cancer is 40 times more common in patients with
UDT compared to the general male population. Unfortunately, orchiopexy does not reduce the
incidence of malignancy, but it makes the testis easier to examine, presumably leading to earlier
detection.
3.
Decreased risk of trauma or torsion:
The abnormally positioned UDT is more prone to
trauma or torsion, and orchiopexy decreases this risk.
4.
Cosmetic/Psychologic considerations.
Preoperative counseling of the parents of a boy with UDT is very important so that they understand the
goals and limitations of surgery. A testis may not be present, or if present, it may not be salvageable. In
addition, injury may result to the testis or associated structures during operation. Neither general
growth and development nor development of secondary sexual characteristics are affected by testicular
position.
Orchiopexy for a palpable UDT involves an inguinal exploration to mobilize the spermatic vessels and vas
deferens to allow the testis to be brought down into the scrotum. Any associated hernia is repaired
appropriately. The scrotum is stretched, and the testis is secured in the deep scrotum, most commonly
with a dartos pouch technique in which the testis is anchored in a space developed between the dartos
fascia and the scrotal skin.
I find laparoscopy helpful in patients in which the UDT is not palpable in the groin. If the vas and
spermatic vessels end blindly, this proves that the testis is absent, and the operation can be concluded
immediately. In the case of an atrophic or very high intra-abdominal testis, an orchiectomy can be
performed if a normal testis is present contralaterally. With a low intra- abdominal testis near the
internal inguinal ring, if it can be mobilized sufficiently, a formal orchiopexy can be performed at the
same time; if the vascular pedicle seems too short, a two- stage Fowler-Stephens approach can be used
in which first the spermatic vessels are divided in the high retroperitoneum at laparoscopy, and then 6
to 12 months later, after a collateral blood supply has developed, an orchiopexy via an inguinal
approach can be performed.
Possible complications following orchiopexy include injury to the vas (1%), injury to the spermatic
vessels leading to testicular atrophy (1% to 8%), and retraction of the testis out of the scrotum (5% to
10%).
In summary, I would like to reiterate a few key points. Retractile testis must be differentiated from UDT
to avoid unnecessary operation. Although ample time should be allowed for full testicular descent to
occur, orchiopexy should be performed in a timely fashion after the first birthday to avoid long-term
damage to the testis. In the case of nonpalpable UDT, laparoscopy offers a minimally invasive approach
to diagnosis and treatment.
Dr. Breaux is a pediatric surgeon and surgical critical care specialist practicing in Grand Junction,
Colorado.