Hypospadias

Hypospadias

Hypospadias is an abnormality in boys in which failure of closure of the urethral lumen leads to an abnormal ventral positioning of the urethral orifice. Embryologically, there is failure of the normal proximal-to-distal fusion of the urogenital folds. Recent reviews suggest a multifactorial etiology, including abnormal androgen production by the fetal testis, limited androgen sensitivity in the target tissues of the developing external genitalia, and/or premature cessation of androgenic stimulation. There are at least several different classification schemes of hypospadias that describe severity of this anomaly depending on position of the urethral meatus: urethral opening low on an otherwise normal glans penis is considered a minor hypospadias; urethral opening on the penile urethra is an intermediate abnormality; and extreme or severe hypospadias consists of a penoscrotal or perineal urethral orifice. Anatomic description identifying the abnormal position of the urethral opening as glanular, penile, penoscrotal or perineal, is perhaps most universal and useful. The incidence of hypospadias is approximately 1 in 300 male births, with the glanular and penile types accounting for approximately 50 to 70% of cases.

Associated abnormalities include enlargement of the utricle which occurs commonly, the size of the utricle in proportion to the severity of hypospadias. Cryptorchidism, inguinal hernia and/or hydrocele are also present in approximately 9% of males with more proximal hypospadias. Abnormalities of kidney ascent and rotation have been described, as has hypospadias as the primary genital abnormality in boys with low imperforate anus. Classic associations are chordee, or abnormal ventral curvature of the penis, and abnormal distribution of the foreskin with a hood of foreskin that is present dorsally and deficient foreskin ventrally.

The diagnosis of hypospadias in usually evident on newborn physical examination though may not always be the case with milder forms. In latter cases, boys may escape diagnosis until newborn circumcision is complete or the foreskin is fully retracted. Consideration must always be given to potential significant underlying and/or associated entities when even a simple, isolated hypospadias is identified.

The literature does not support routine imaging of the urinary tract for evaluation of hypospadias, particularly when a minor or intermediate defect. VCUG is most commonly done in patients exhibiting an intermediate or extreme hypospadias, and in those requiring extensive urethroplasty. Ventral urethral stricture or diverticulum may occur following repair that requires fluoroscopic follow-up. Routine renal ultrasound is probably not necessary as incidence of associated renal anomalies is low. Depending on severity and associated findings, treatment may include hormonal manipulation, orthoplasty for chordee, and urethroplasty for neourethra formation.

Reference: Campbell’s Urology, 7th ed, pp 2284-2302.
Practical Pediatric Imaging; Diagnostic Radiology of Infants and Children, 3rd ed, pp1082-1084.

Differential Diagnosis

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Epispadias

A. Ventral urethral ectasia related to prior hypspadias repair

B. Anastomotic narrowing

C. Utricle

B

A

C

A. Verumontanum

B. Anterior urethra

C. Hypospadias opening along penile base

D. Short malformed penis