In maldescensus testis (MDT; MT) (synonyms: Testicular retention, Retentio testis inguinalis, abdominalis, cryptorchidism; ICD-10-GM Q53.-: Nondescensus testis) is a disordered descent of the testis (= primary undescended testis/descensus testi). The testis usually descends from the abdomen into the scrotum during development. If this migration fails to occur, the testis may remain in the abdomen [abdominal testis retentio (retentio testis abdominalis; cryptorchidism “cryptorchidism “* )] or in the groin [inguinal testis retentio (retentio testis inguinalis; “cryptorchidism”)] (about 50-60% of cases). In addition, the testis may take a “wrong” path to the testis and thereby migrate below the groin or even into the thigh (testicular ectopy; prefascial testicular ectopy (approx. 40 %); ectopia penilis; ectopia femoralis, ectopia perinealis).
* The term cryptorchidism is used when the testis is not palpable and has an intra-abdominal location (retentio testis abdominalis) or the testis is absent (anorchia).
Furthermore, one can distinguish:
- Pendulous testis (retactile testis; Engl. retractile testis) – these are normally developed testes, but they can temporarily pull up into the groin; does not require therapy and should be observed.
- Gleithoden (Retentio testis prescrotalis) – in this case, the testis lies in the groin, but can be easily pulled into the testicular compartment, but immediately slides back into the groin position → conservative hormone therapy within the first 12 months of life.
Maldescensus testis is the most common congenital anomaly of the genitourinary tract. In addition to maldescensus testis, there is also a secondary ascensus after descensus (= secondary undescended testis) has already taken place.
The prevalence of primary maldescensus testis is 3-4% of all newborns and up to 30% in premature infants. At the end of the first year of life, the prevalence is 1-2%, bilateral (bilateral) in about 30% of cases.
Course and prognosis: During the first six months, the patient is initially kept waiting and the course is regularly monitored, since spontaneous descensus testis (testicular descent) is still possible during this period. However, this only occurs in up to seven percent. If the testicle cannot be permanently palpated in the scrotum, pharmacotherapy (drug therapy) is started. Ideally, the therapy should begin after the sixth month of life and be completed by the first year of life! If this therapy is unsuccessful, the testis is usually surgically fixed in the scrotum by the 12th month of life to prevent subsequent damage (fertility problems and a higher risk of testicular cancer). Approximately 1.4-3.8% of boys undergo surgery for undescended testis.For the paternity rate after surgical therapy, see “Consequelae.”
