Undescended testis is a frequent anomaly.
It occurs in 2 % of the neonates, in 20 % in prematurity, in 1 % at the age of 1 year, and somewhat less at the end of puberty.

1. Impairment of the fertility.
2. Veiling of pathologies which occur in an undescended testis.
3. Psychological embarrassment.
4. Increased risk of malignancy.

Unknown.

Testicular retention with arrest in the line of normal descent: Intraabdominal, canalicular and high scrotal testis (near the neck of the scrotum).
Testicular ectopy with a position beyond the line of normal descent: Lateral of the external inguinal ring (prefascial testicular ectopy), perineal, femoral, pubopenile, transverse contralateral ectopy.
Combination with other malformations such as testicular-epididymal fusion anomaly, long loop-vas cryptorchidism, and interruption of the vas.
Undescended testes are a frequent associated anomaly of many urogenital and other malformations, syndromes and chromosomal aberrations.

In undescended testis an increasing loss of spermatogones may be observed as early as in the first year of life, and again prior to puberty. It is not known if this cell death is a combined anomaly of undescended testis, or if it is a sequel of the high position of the testicle.

History: The parents observe during personal hygiene of their children a permanently or occasionally empty scrotum.
Local findings: During a routine examination, a unilateral or bilateral empty scrotum is found, and the testicle cannot be palpated at all or at an abnormal site.
The local findings depend on the type of undescended testis and on the condition and technique of examination.
Clinical Skills: normally developed or hypoplastic scrotum; examination of a quiet child in a recumbent position, without haste, and with warm hands; examination of the child in a fi position.

Beyond the age of one year, a descent does not occur any more. On the other hand, in (late) ascending testis the position is normal at the end of the first year, but becomes high following growth. This course may be observed in some children with cerebral palsy, or in some cases of retractile testis. In adults with undescended testis (with or without pre-existing surgery) a carcinoma in situ or a malignancy may be observed.

The differential diagnosis includes:
1. Retractile testis.
2. Secondary undescended testis following repair of an inguinal hernia or in (late) ascending testis.
3. Anorchism as a primary anomaly, or as a sequel of an incarcerated inguinal hernia, or of a testicular torsion.

In case of unilaterally or bilaterally non-palpable testis, ultrasound and clinical examination in general anesthesia may be performed, and, following these examinations in case of bilateral undescended testis, endocrinological examinations, and a diagnostic laparoscopy.
In every case of undescended testis a precise clinical examination of the external genitals is necessary, and the exclusion of associated anomalies.

For the indication of treatment (hormone versus surgical treatment) it is important to know that the type of undescended testis can often be recognized only during surgery.

Surgery is indicated in every case of non-palpable testis, of ectopic testis, and of undescended testis combined with an inguinal hernia.
One possible procedure is Shoemaker's orchidopexy. In case of non-palpable testis the choice of the intervention(s) depends on the laparoscopic findings.
Except for cases with a combined inguinal hernia, surgery is performed at 1 to 2 years of age, or prior to school-attendance in case of late diagnosis.

Fatherhood in unilateral or bilateral undescended testis with palpable testicle is observed in more than 80 %, or in up to 60 %, respectively. However, there is no paternity in non-palpable bilateral testis.