Embryology · Urogenital system
Hypospadias and epispadias !
- Malformation
The urethra does not end at the tip of the penis: in hypospadias it opens underneath, in epispadias on top.
Updated 2026-11-01
See it in 3D: Glans penis · Spongy urethra · Corpus spongiosum · Skin of penis · Scrotum
What it is
Hypospadias is one of the commonest genital malformations in males: the urethral meatus opens on the underside of the penis, the scrotum or the perineum because the urogenital folds do not finish fusing. Epispadias, far rarer, leaves the meatus on the dorsal side and is usually part of the exstrophy–epispadias complex. Both are defects of urethral closure, but they happen at different times and by different mechanisms.
Embryological cause
- Hypospadias: with insufficient DHT action, the urethral plate opens but the urogenital folds do not close the groove up to the glans tip.
- The earlier the closure stops, the more proximal the meatus (glanular, penile, penoscrotal, perineal).
- Factors: genetic, endocrine (androgen synthesis or action) and environmental; maternal progestins and assisted reproduction have been linked.
- Epispadias: the genital tubercle forms too far caudally or mesenchyme fails to reinforce the cloacal membrane (weeks 4–5); the urethra stays open dorsally.
Markers
- AR
- SRD5A2
- DHT
How it presents
- A newborn with a ventral meatus, dorsally hooded foreskin and sometimes a curved penis.
- Cryptorchidism and inguinal hernia often accompany proximal forms.
- Proximal forms with a bifid scrotum can give atypical-looking genitalia.
- Epispadias: dorsal meatus, short broad penis, dorsal curvature; often incontinence and pubic diastasis.
- In girls, epispadias appears as a bifid clitoris and a wide urethral meatus.
Diagnosis
- Diagnosis is clinical, on the newborn examination.
- Proximal hypospadias or a non-palpable testis: karyotype and hormonal evaluation.
- Epispadias: renal ultrasound and a pelvic X-ray to assess pubic diastasis.
Test yourself
Think of the answer, then tap the question to see it.
Which embryological failure causes hypospadias?
The urogenital folds do not complete their fusion on the ventral side, because of insufficient androgen action between weeks 8 and 14.
Which combination in a newborn with hypospadias calls for evaluation of a difference of sex development?
Proximal hypospadias with one or both testes not palpable; a karyotype is indicated.
Which malformation is epispadias almost always associated with?
Bladder exstrophy, within the exstrophy–epispadias complex.
Why is a boy with hypospadias not circumcised?
Because the foreskin is kept as tissue for the surgical repair.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- External genitalia and their male–female homologues
- Bladder, urachus and urethra
- Sex determination: SRY, anti-Müllerian hormone and testosterone
- Cryptorchidism
- Differences of sex development: CAH, AIS and 5α-reductase
- Bladder exstrophy
- Androgens, diethylstilbestrol and other hormones
Related conditions
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: Hypospadias | Birth Defects | CDC (Centers for Disease Control and Prevention, 2024); Hypospadias: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2024); Embryology, Urethral Folds - StatPearls - NCBI Bookshelf (StatPearls Publishing (NCBI Bookshelf), 2023); Epispadias - StatPearls - NCBI Bookshelf (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.