Epispadias is rare, with a reported incidence of 1 in 117,000 males. It is a failure of dorsal closure of the urethra, and varies from a mild glanular defect on a covered penis, to the penopubic variety with complete incontinence in males and females, to the complete variety associated with bladder extrophy. Epispadias occurs as a result of defective migration of the genital tubercle primordii, which migrate toward midline superior to the cloacal membrane to form the genital tubercle at about the 5th week of gestation. The resulting malformation consists of a defect on the dorsal wall of the urethra. The normal urethra is replaced by a broad, mucosal strip lining the dorsum of the penis, with incompetence of the sphincter mechanism and a displaced penile meatus. The meatus may be found on the glans, penile shaft, of penopubic region. Varying degrees of severity occur, from an open bladder neck and urethra, to involvement of only the distal urethra. Because closure of the bladder and urethra in the embryo occur from cranial to caudal, extrophy of the bladder always includes epispadias, but epispadias can exist without extrophy. The bladder extrophy-epispadias spectrum of abnormalities causes a low midline abdominal wall defect and varying degrees of vesicourethral exposure. Nearly all patents with epispadias are boys, and all types of epispadias are associated with varying degrees of dorsal chordee. Associated anomalies include deformities of the external genitalia, diastasis of the public symphysis, inguinal hernia, vesicoureteral reflux, deficiency of the urinary continence mechanism, renal agenesis and ectopia. Female epispadias is much less frequent, occurring in approximately 1 of every 484,000 patients. In female epispadias, the urethral orifice may simply appear patulous, dorsally split along most of the urethra, or in most severe cases the urethral cleft involves the entire length of the urethra and sphincteric mechanism. The genital defect is characterized by a bifid clitoris, and the labia minora are usually poorly developed. The vagina and internal genitalia are usually normal. The diagnosis of epispadias is obvious on physical examination at birth. Plain radiography is often utilized for evaluation of the pelvis and pubic bones. MRI or ultrasound of the spine may be performed to evaluate for spinal cord abnormalities. Depending on the spectrum of associated abnormalities, VCUG may be performed to evaluate bladder capacity, reflux, and integrity of the sphincteric mechanism. It is not typically done prior to repair. Renal ultrasound can be used to detect hydronephrosis or renal scarring. The primary objectives of surgical repair of epispadias include achievement of urinary continence with preservation of the upper urinary tract and reconstruction of cosmetically acceptable genitalia. Urethroplasty and bladder neck reconstruction are mainstays of therapy. Bladder augmentation may be performed if low bladder capacity is present. Pre and post-operative imaging interpretation depends on a thorough understanding of the spectrum of associated anomalies that may be present. Reference: Campbell’s Urology, 7th ed, pp 2181-2188. Practical Pediatric Imaging; Diagnostic Radiology of Infants and Children, 3rd ed, pp1080-1081.
Epispadias
A. Abnormal contour of dorsal urethra compatible with epispadias repair
B. Posterior Urethra
C. Distal Urethra
A
B
C
Differential Diagnosis
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Hypospadias
Repaired
A. Wide pubis symphysis
B. Absent sphincter impression and absent prostate
C. Ill-defined urethra
A C B