Hypo = under, epi = on top. In hypospadias the urethral opening sits on the ventral (under) surface of the penis, usually with a dorsally hooded foreskin and a downward bend (ventral chordee); it is common (about 1 in 250 male births in the United States), comes from incomplete fusion of the urethral folds, and the must-know pearl is no newborn circumcision, because the foreskin is used in the repair at 6–18 months. In epispadias the opening sits on the dorsal (top) surface; it is rare, more than 90% of cases belong to the bladder exstrophy–epispadias complex, and the stem usually adds bladder exstrophy, a widened pubic symphysis or urinary incontinence.
The 5-second rule
- Find the meatus. Under the shaft (ventral, the "6 o'clock" position) means hypospadias. On top (dorsal, "12 o'clock") means epispadias.
- Check the hood and the bend. Hypospadias: the foreskin is missing underneath, so it sits on top as a dorsal hood, and the penis bends down (ventral chordee). Epispadias: a short penis that bends up (dorsal chordee), with a ventrally hooded foreskin.
- Name the partner. Epi goes with exstrophy (same first letter). Hypospadias goes with undescended testes and inguinal hernia, and with a disorder of sex development (DSD) when it is severe and the testes are undescended.
Hypospadias vs epispadias side by side
| Feature | Hypospadias | Epispadias |
|---|---|---|
| Meatus | Ventral: near the glans, along the shaft, or as far back as the scrotum or perineum | Dorsal: glans, shaft or penopubic junction |
| How common | About 1 in 250 male births; distal forms are 60–70% of cases | Rare: isolated epispadias about 1 in 100,000–160,000 males; most cases occur with bladder exstrophy |
| Embryology | Urethral folds fail to fuse, an androgen-dependent step | Part of the exstrophy–epispadias complex, from abnormal cloacal membrane development; review books summarize it as a malpositioned genital tubercle |
| Foreskin | Dorsal hood (deficient ventrally) | Ventral hood |
| Curvature | Ventral chordee | Dorsal chordee with a short penis |
| Associations | Undescended testes and inguinal hernia (the most common associated anomalies, especially with proximal forms); DSD when severe with undescended testes | Bladder exstrophy, pubic diastasis |
| Continence | Not a feature | Often impaired; almost always in the penopubic form, because the bladder neck is incompetent |
| Management | No circumcision; surgical repair at 6–18 months | Surgical reconstruction in early childhood |
Embryology: why each defect happens
The external genitalia start out identical in both sexes. The genital tubercle becomes the glans (of the penis or clitoris), the urethral folds become the ventral shaft and penile urethra in males (the labia minora in females), and the labioscrotal swellings become the scrotum (the labia majora). In males, dihydrotestosterone drives the urethral folds to fuse along the underside of the shaft like a zipper, closing the penile urethra. When that closure stops short, the urethra opens on the ventral side: hypospadias. Because the fusion step depends on androgen, a severe hypospadias with undescended testes should prompt a search for undervirilization.
Epispadias is a midline defect on the other side. It sits on a spectrum with bladder exstrophy: the cloacal membrane ruptures early, before mesenchyme has grown in to reinforce the lower abdominal wall, leaving the dorsal urethra, and in exstrophy the bladder, open. Rupture after the urorectal septum has divided the cloaca gives classic bladder exstrophy; rupture before it gives the most severe form, cloacal exstrophy.
When hypospadias signals a disorder of sex development
- Hypospadias with undescended testes: the American Urological Association advises assessing for a DSD, with more concern the more severe the hypospadias, and a karyotype is recommended when one or both testes are undescended.
- Bilateral nonpalpable testes in a baby who looks male: consult a specialist immediately. The AUA workup first asks whether the infant has congenital adrenal hyperplasia; 21-hydroxylase deficiency causes over 90% of CAH and is the most common cause of atypical genitalia in young children, and newborn screening measures 17-hydroxyprogesterone. The enzyme blocks are compared in the congenital adrenal hyperplasia overview.
- Isolated hypospadias with both testes in the scrotum is usually a purely urologic problem: refer to pediatric urology and leave the foreskin intact. Undescended testes on their own are covered in the cryptorchidism Q-bank breakdown.
Look-alikes on the answer list
| Answer choice | What its stem shows | Why it is not hypospadias |
|---|---|---|
| Epispadias | Dorsal meatus, upward curvature, exstrophy, incontinence | Opposite surface of the penis |
| Bladder exstrophy | Red bladder plate on the lower abdomen with constant urine leakage, pubic diastasis, anteriorly placed anus, short penis with dorsal chordee | The bladder and abdominal wall are open; epispadias is part of this complex |
| Posterior urethral valves | Weak stream, palpable bladder, urinary tract infection; before birth, bilateral hydronephrosis, a thick-walled bladder, a "keyhole" dilated posterior urethra and oligohydramnios with pulmonary hypoplasia | An obstruction with a normally placed meatus; diagnosed by voiding cystourethrogram |
| Prune belly syndrome | Deficient abdominal wall muscles, dilated urinary tract, bilateral undescended testes | Needs the full triad; over 95% of patients are boys |
| DSD (for example, CAH) | Bilateral nonpalpable gonads, or severe hypospadias with undescended testes | Needs a karyotype and specialist evaluation |
Exam traps
- Don't circumcise a newborn with hypospadias; the foreskin is needed for the repair.
- The hood sits opposite the meatus. A dorsal hood goes with a ventral meatus (hypospadias); a ventral hood goes with a dorsal meatus (epispadias).
- Incontinence points to epispadias, especially the penopubic type with an incompetent bladder neck.
- Severe hypospadias with undescended testes, or bilateral nonpalpable testes, is a DSD question, not a routine repair question.
- Posterior urethral valves are an obstruction, so the meatus is normal and the clues are hydronephrosis, a distended bladder and oligohydramnios.
- Bladder exstrophy carries a lifelong cancer risk of about 1–2%, mostly adenocarcinoma of the bladder.
Worked example
Vignette. A 1-day-old boy born at term has a urethral opening on the underside of the penis just below the glans. The foreskin is absent on the ventral side and gathered on top like a hood, and the penis curves downward during an erection. Both testes are palpable in the scrotum, and he voids with a normal stream. His parents ask for a circumcision before discharge. What is the best response?
Answer: Defer circumcision and refer to pediatric urology for hypospadias repair, usually at 6–18 months of age.
Reasoning: A ventral meatus with a dorsal hood and ventral chordee is hypospadias, and the foreskin is used to reconstruct it. Epispadias would put the meatus on top and usually come with exstrophy; posterior urethral valves cause obstruction rather than a misplaced meatus; prune belly syndrome needs the triad; and with both testes descended and a distal defect, a DSD is unlikely.
Key takeaways
- Hypo = under (ventral); epi = on top (dorsal).
- Hypospadias: about 1 in 250 boys; the urethral folds fail to fuse; dorsal hood and ventral chordee; no circumcision; repair at 6–18 months.
- Hypospadias with undescended testes (especially when severe) or bilateral nonpalpable testes calls for a DSD evaluation, starting with a karyotype and a check for CAH.
- Epispadias: rare; more than 90% of cases occur within the exstrophy–epispadias complex; dorsal chordee, pubic diastasis and incontinence.
- Distractors: posterior urethral valves mean obstruction, prune belly means the triad, and bladder exstrophy means an open bladder plate.
Sources
- Hypospadias (Archived) — StatPearls, NCBI Bookshelf
- Epispadias — StatPearls, NCBI Bookshelf
- Embryology, Urethral Folds — StatPearls, NCBI Bookshelf
- Bladder Exstrophy — StatPearls, NCBI Bookshelf
- Posterior Urethral Valves — StatPearls, NCBI Bookshelf
- Evaluation and Treatment of Cryptorchidism: AUA Guideline — American Urological Association
Frequently Asked Questions
What is the difference between hypospadias and epispadias?
Hypospadias places the urethral opening on the ventral (under) side of the penis, usually with a dorsally hooded foreskin and downward curvature. Epispadias places it on the dorsal (top) side, usually with upward curvature, and most cases occur with bladder exstrophy. A quick rule is hypo = under and epi = on top.
Why can't a baby with hypospadias be circumcised?
The foreskin is used as tissue for the surgical repair, so circumcision is avoided whenever the penis is abnormal. The repair is usually done between 6 and 18 months of age by a pediatric urologist.
What causes hypospadias embryologically?
Hypospadias results from incomplete fusion of the urethral folds, which normally close along the underside of the penis under the influence of dihydrotestosterone to form the penile urethra. Because this step depends on androgen, severe hypospadias with undescended testes should prompt an evaluation for a disorder of sex development. Epispadias has a different origin: it belongs to the exstrophy spectrum caused by abnormal development of the cloacal membrane.
Is epispadias associated with bladder exstrophy?
Yes. More than 90% of epispadias cases occur as part of the bladder exstrophy–epispadias complex, and isolated epispadias is rare. Associated features include a widened pubic symphysis and urinary incontinence, which is almost always present in the penopubic form because the bladder neck is incompetent.
When does hypospadias need a disorder of sex development workup?
A disorder of sex development should be considered when hypospadias occurs with undescended testes, and the concern rises with more severe hypospadias; a karyotype is recommended in that setting. A newborn who looks male but has bilateral nonpalpable testes needs immediate specialist evaluation, including assessment for congenital adrenal hyperplasia. Isolated hypospadias with both testes in the scrotum usually needs only a urology referral.