[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Embryology](https://durgical.com/en/embryology/) › [Urogenital system](https://durgical.com/en/embryology/#a-urogenital) › Cryptorchidism [Embryology](https://durgical.com/en/embryology/) · [Urogenital system](https://durgical.com/en/embryology/#a-urogenital) # Cryptorchidism - Malformation One or both testes did not come down into the scrotum before birth. It is the commonest genital malformation in boys. Updated 2026-11-01 **See it in 3D:** [Scrotum](https://durgical.com/en/anatomy/scrotum/) · [Inguinal canal](https://durgical.com/en/anatomy/inguinal-canal/) · [Spermatic cord](https://durgical.com/en/anatomy/spermatic-cord/) · [Testicular arteries](https://durgical.com/en/anatomy/testicular-artery-pelvis/) ## Key points - It is the commonest congenital genital anomaly in males; much more frequent in preterm babies. - The testis most often stops in the inguinal canal. - Many descend on their own in the first months of life; after that it is rare. - Risks: infertility, germ cell tumour (also in the other testis), torsion and inguinal hernia. - Retractile testis: comes down easily and stays in the scrotum; it is not cryptorchidism. - Both testes impalpable in a newborn: exclude a 46,XX girl virilized by congenital adrenal hyperplasia. ## What it is Cryptorchidism is a testis that stopped somewhere along its normal path from the abdomen to the scrotum. It affects about 3% of full-term boys and many more preterm boys, and some testes come down on their own in the first months. It matters because a testis outside the scrotum is linked to lower fertility and a higher risk of testicular cancer. ## Embryological cause - Failure of the transabdominal phase (weeks 8–15): a defect of INSL3, its receptor or the gubernaculum; the testis stays intra-abdominal. - Failure of the inguinoscrotal phase (third trimester): androgen deficiency or impaired action; the testis stays in the inguinal canal. - Prematurity: birth interrupts a descent that mostly happens in the third trimester. - Ectopic testis: it leaves the normal route (perineal, femoral, at the base of the penis). ## Markers - INSL3 - RXFP2 - AR ## How it presents - An empty or small hemiscrotum, with the testis palpable in the groin or not palpable. - Often accompanied by an indirect inguinal hernia through a patent processus vaginalis. - Associated with hypospadias, especially proximal forms. - Long term: lower sperm production and higher risk of seminoma, which persists even after the testis is brought down. ## Diagnosis - Diagnosis rests on repeated physical examination, with the child relaxed and squatting or cross-legged. - Ultrasound does not replace the examination and rarely changes management. - Bilateral impalpable testes, or with hypospadias: karyotype and hormonal profile. - Laparoscopy locates an intra-abdominal testis or confirms its absence. ## Memory aid “The testis left on the staircase”: it stopped on one step of the way, and the higher it stopped, the warmer it stays and the more it suffers. ## Test yourself Think of the answer, then tap the question to see it. ## Where is an undescended testis most often found? In the inguinal canal, along the normal route of descent. ## Which hormone and which phase of descent fail in an intra-abdominal testis? The transabdominal phase, which depends on INSL3 from Leydig cells acting on the gubernaculum. ## How is a retractile testis told apart from cryptorchidism? A retractile testis can be brought into the scrotum and stays there when released; it retracts through the cremasteric reflex and is not a malformation. ## Why do two impalpable testes in a newborn call for a karyotype? Because the baby may be a 46,XX girl with congenital adrenal hyperplasia and virilized genitalia, who is also at risk of a salt-wasting crisis. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/embryology/cryptorchidism/) ## See it in 3D The structures of Durgical's 3D anatomy where it is found. - [Scrotum](https://durgical.com/en/anatomy/scrotum/) - [Inguinal canal](https://durgical.com/en/anatomy/inguinal-canal/) - [Spermatic cord](https://durgical.com/en/anatomy/spermatic-cord/) - [Testicular arteries](https://durgical.com/en/anatomy/testicular-artery-pelvis/) ## Related - [Gonads and the descent of the testis](https://durgical.com/en/embryology/gonads-and-the-descent-of-the-testis/) - [Processus vaginalis: hydrocele and indirect inguinal hernia](https://durgical.com/en/embryology/processus-vaginalis-hydrocele-and-indirect-inguinal-hernia/) - [Hypospadias and epispadias](https://durgical.com/en/embryology/hypospadias-and-epispadias/) - [Differences of sex development: CAH, AIS and 5α-reductase](https://durgical.com/en/embryology/differences-of-sex-development-cah-ais-and-5-reductase/) - [Sex determination: SRY, anti-Müllerian hormone and testosterone](https://durgical.com/en/embryology/sex-determination-sry-anti-mullerian-hormone-and-testosterone/) ## Related conditions - [Cryptorchidism (undescended testis)](https://durgical.com/en/conditions/cryptorchidism/) - [Testicular cancer](https://durgical.com/en/conditions/testicular-cancer/) - [Inguinal hernia](https://durgical.com/en/conditions/inguinal-hernia/) - [Testicular torsion](https://durgical.com/en/conditions/testicular-torsion/) [← All of embryology](https://durgical.com/en/embryology/) Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given. Sources: [Undescended testicle: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000973.htm) (MedlinePlus, U.S. National Library of Medicine, 2024); [Embryology, Testicle - StatPearls - NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK557763/) (StatPearls Publishing (NCBI Bookshelf), 2023). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/embryology/cryptorchidism/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/embryology/cryptorchidism/