Hipospadia

01Pathophysiology

Hypospadias results from the failure of complete fusion of the urethral folds along the ventral surface of the developing penis. Normally, under the influence of dihydrotestosterone (DHT), which is converted from testosterone by the enzyme 5-alpha reductase, the urethral folds fuse in a proximal-to-distal direction between gestational weeks 8 and 14. This process extends the urethra to its normal position at the tip of the glans. When androgen signaling is disrupted at any point during this window, fusion halts prematurely, leaving the meatus at an abnormal ventral position.

The timing of the disruption determines the severity: an early insult produces a more proximal defect (penoscrotal or perineal), while a late disruption produces a distal defect (glanular or subcoronal). This is why the classification of hypospadias directly mirrors the embryologic sequence of urethral fold closure.

Chordee (ventral curvature of the penis) is explained by the presence of fibrous tissue on the ventral aspect where the urethra failed to develop. This tethers the penis ventrally and causes curvature, particularly during erection. The dorsal hooded foreskin occurs because the prepuce normally forms by fusing circumferentially after urethral closure is complete; since the ventral urethra did not close, the ventral foreskin also fails to form, leaving an incomplete "hood" on the dorsal side.

Understanding the androgen-dependent nature of this defect is important. Conditions that reduce androgen production or action (such as placental insufficiency, 5-alpha reductase deficiency, or androgen receptor mutations) increase the risk. Similarly, exogenous endocrine-disrupting chemicals in the maternal environment are implicated. This connects hypospadias to the broader concept of disorders of sex development, which is why severe cases warrant a hormonal and genetic workup.

02Classification and Clinical Manifestation

Key clinical point for the exam: The more proximal the defect, the higher the likelihood of associated anomalies (cryptorchidism, inguinal hernia) and the greater the need for a DSD evaluation. A vignette describing a newborn with a perineal urethral opening, severe chordee, bifid scrotum, and nonpalpable testes is testing your ability to recognize that this child needs a karyotype and endocrine workup before gender assignment is finalized.

03Diagnostic Workup

Hypospadias is fundamentally a clinical diagnosis made on physical examination at birth. No imaging or lab work is needed for the straightforward distal case. The examiner expects you to know that the diagnosis is made by inspection alone in the majority of patients.

The workup escalates when the presentation raises concern for a disorder of sex development. The classic trigger is proximal (penoscrotal, scrotal, or perineal) hypospadias combined with bilateral nonpalpable testes. In this scenario, the child may actually be a 46,XX female with virilizing congenital adrenal hyperplasia (CAH), which is a life-threatening condition if the salt-wasting form goes undetected. This is why a karyotype is ordered: it is the test that defines chromosomal sex. Alongside the karyotype, serum electrolytes are checked urgently because a salt-wasting crisis (hyponatremia, hyperkalemia) can be fatal in the first weeks of life.

17-hydroxyprogesterone is the confirmatory marker for 21-hydroxylase deficiency (the most common form of CAH). If the hormonal profile is needed to clarify the androgen axis, testosterone, DHT, and gonadotropins (LH, FSH) are drawn. An elevated testosterone-to-DHT ratio, for example, raises suspicion for 5-alpha reductase deficiency.

Pelvic ultrasound identifies whether mullerian structures (uterus) are present, which would indicate an XX karyotype or a mixed gonadal disorder. A VCUG is not routine but may be indicated in complex proximal cases to evaluate for a prostatic utricle or other structural urogenital variants.

04Management and Treatment

The single most testable fact in hypospadias management is: do not circumcise. When a newborn male is found to have hypospadias, routine neonatal circumcision must be deferred. The foreskin serves as the primary source of vascularized tissue (the "preputial flap") used during surgical reconstruction of the urethra. If the foreskin has been removed, the surgeon loses the best available local tissue, making the repair substantially more complex. If a vignette describes a newborn with a dorsal hooded foreskin and a ventral urethral meatus and asks for the "next best step," the answer is referral to a pediatric urologist and avoidance of circumcision.

Timing of surgical repair is ideally between 6 and 18 months of age. The American Academy of Pediatrics and most pediatric urology guidelines support this window because it balances anesthetic safety, penile growth adequate for repair, and minimal psychological impact on the child. Operating before 6 months carries higher anesthetic risk, while delaying beyond 18 months increases the risk of psychological and behavioral issues related to genital procedures.

Preoperative hormonal stimulation is considered in cases where the penis is small or the glans is underdeveloped. Topical testosterone or DHT cream applied to the penis for 4 to 6 weeks before surgery can increase tissue bulk and vascularity, improving surgical outcomes. In some centers, a short course of intramuscular testosterone enanthate (25 mg IM, given monthly for 1 to 3 doses) is used instead.

Surgical technique depends on the type and severity:

• Distal hypospadias (glanular, coronal, subcoronal): most commonly repaired with the TIP (Tubularized Incised Plate, or Snodgrass) procedure, a single-stage outpatient surgery with high success rates.

• Proximal hypospadias (penoscrotal, scrotal, perineal): often requires a two-stage repair. The first stage releases the chordee and places a tissue graft (buccal mucosa or preputial skin). The second stage, performed 6 months later, tubularizes the graft into a neo-urethra.

Postoperatively, a urethral stent or small catheter is left in place for about 5 to 14 days to allow healing. Prophylactic antibiotics (commonly trimethoprim-sulfamethoxazole or cephalexin) are given while the stent is in place. Oxybutynin is sometimes prescribed to reduce bladder spasms triggered by the catheter.

Long-term complications include urethrocutaneous fistula (the most common complication, presenting as a secondary urinary stream from the ventral penile surface), meatal stenosis, urethral stricture, and urethral diverticulum. Follow-up extends through puberty to monitor for these complications, especially as the penis grows.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The single most common way students lose points on hypospadias questions is by failing to recognize that circumcision is contraindicated. A vignette will describe a routine newborn exam, mention a ventral meatal opening and a dorsal hooded foreskin, and then ask for the next step. The trap answer is "schedule circumcision" or "reassurance and routine care." The correct answer is to defer circumcision and refer to pediatric urology for planned surgical repair. This is the core concept being tested: pattern recognition of the dorsal hooded prepuce as a red flag for hypospadias, followed by the appropriate initial management decision.

The second common trap involves proximal hypospadias with bilateral cryptorchidism. Students correctly identify hypospadias but fail to recognize that the combination of a perineal meatus plus nonpalpable bilateral testes demands a DSD evaluation, including karyotype and hormonal studies. The vignette is testing whether you can distinguish a straightforward surgical case from one that requires urgent genetic and endocrine investigation. If you see a newborn with ambiguous genitalia and you do not think "rule out CAH," you will miss the life-threatening diagnosis of salt-wasting congenital adrenal hyperplasia.

A third pearl worth internalizing: the timing of repair (6 to 18 months) is a testable fact. If a vignette asks when the child should undergo surgery, answers suggesting the neonatal period or after age 3 are distractors. The window of 6 to 18 months is the standard recommendation, balancing surgical feasibility with developmental and psychological considerations.

Finally, remember that hypospadias is a clinical diagnosis. Lab work and imaging are not needed unless the presentation suggests DSD. Do not order unnecessary tests on a straightforward distal case. The exam rewards you for knowing when to investigate further and when to simply recognize the diagnosis and refer.