Urethral Anomalies and Urethral Prolapse in Children

Updated: Jan 04, 2023
  • Author: Jyoti Upadhyay, MD, FAAP; Chief Editor: Marc Cendron, MD  more...
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Practice Essentials

This article discusses various urethral anomalies observed in male infants and children and the distinct entity of urethral prolapse in prepubescent females. [1, 2]  Urethral prolapse is a protrusion of urethral mucosa beyond the urethral meatus and generally occurs in prepubertal black girls or in postmenopausal white females. [3]  This article discusses the pediatric entity of urethral prolapse.

Similarities in the modes of presentation of these conditions are striking, underscoring the importance of a thorough history, physical examination, and radiologic imaging with careful and complete cystourethrography, ultrasonography (US), or endoscopy.

Treatment of urethral prolapse ranges from conservative therapy to various surgical techniques. In the author's view, conservative measures should be used in the milder cases of urethral prolapse or when general anesthesia is contraindicated because the results of medical treatment are less predictable than those of surgery. Certainly, when the urethral mucosa appears gangrenous or necrotic, conservative measures are not appropriate. Treatment of the other urethral anomalies discussed in this article is mostly operative. Urinary tract infections (UTIs) are managed with conventional treatment.



Lacuna magna

Lacuna magna, also known as sinus of Guérin, is a dorsal diverticulum in the roof of the fossa navicularis presenting either as a pit or a 4- to 6-mm sinus, dorsal and parallel to the urethra. This lesion is thought to arise embryologically from an incomplete fusion between the ingrowing ectoderm at the tip of the penis and the glandular urethra.

Urethral duplications

Urethral duplications are rare anomalies characterized as epispadiac, hypospadiac, and Y-type. [4, 5]  They may be either complete, if venting externally, or incomplete, in which case the connection with the urinary tract varies.

In complete duplications, the patient may void with a double stream. Epispadiac duplications are usually associated with significant dorsal curvature of the penis. The most common type of urethral duplication is the Y-type; individuals with Y-type urethral duplication have an orthotopic meatus and a perineal meatus, through which most of the urine passes. The etiology of these conditions is unknown.

Urethral duplications may be associated with other abnormalities (eg, anorectal malformations). [6]

Anterior urethral valves

Anterior urethral valves [7] (AUVs) are rare anomalies, occurring seven to eight times less frequently than posterior urethral valves (PUVs), but with consequences just as devastating.

These lesions can occur anywhere in the anterior urethra, and the valve mechanism is usually formed by an associated diverticulum; isolated valves formed by cusps or irislike diaphragms have also been reported. The diverticulum has been postulated to arise from incomplete formation of the ventral corpus spongiosum, an incomplete urethral duplication, or a congenital cystic dilation of a periurethral gland. However, these lesions are embryologically distinct from the much more common PUVs and occur distal to the urinary sphincter.


Megalourethra can be described as a urethral diverticulum that affects the entire penile urethra. Two types, scaphoid and fusiform, have classic descriptions. Scaphoid megalourethras have an absence of corpus spongiosum, whereas fusiform megalourethras lack both spongiosum and corpora cavernosa. Often associated with lethal congenital anomalies, fusiform megalourethras are present in some stillborns; therefore, this finding has more academic than clinical pertinence.

Temporary obstruction during early development may be an etiologic factor in fusiform megalourethra. In the scaphoid type, in which failure of development of erectile tissue is present, a mesenchymal defect is suggested, akin to what is observed in prune belly syndrome.

Anterior urethral diverticula

Anterior urethral diverticula [7] occur in males and may involve the proximal part of the penile urethra and the distal part of the bulbous urethra. An underlying defect in the spongiosum is suggested, as observed in scaphoid megalourethra. An alternative possibility is that these lesions may result from the rupture of a periurethral cyst or a partial duplication of the urethra.

Urethral polyps

Urethral polyps are rare anomalies, characterized as benign urothelium-lined masses attached to a fibrovascular stalk arising from the verumontanum, presenting almost exclusively in boys. Urethral polyps' association to the verumontanum suggests the embryologic persistence of müllerian structures. Some of these polyps, diagnosed later in life, may represent acquired lesions.

Cowper duct cysts

Cowper duct cysts involve the Cowper glands, which are two paired periurethral structures located in the urogenital diaphragm. The Cowper glands are drained by ducts 2-3 cm in length that empty into the bulbous urethra through two small flush openings. These glands, homologous with the Bartholin gland in the female, secrete a clear fluid that functions as a lubricant and a coagulation factor for semen during ejaculation. Abnormalities of these glands and their ducts may result from obstruction and, less frequently, trauma and infection.

Urethral prolapse

Urethral prolapse is the complete protrusion of the urethral mucosa beyond the meatus in females. This is an uncommon condition observed particularly in prepubertal black and Latin American girls. An increased incidence has been reported in children from the lower socioeconomic strata.

This condition is thought to result from poor attachments between the longitudinal and circular oblique smooth-muscle layers and the mucosa of the urethra in association with recurrent episodes of increased intra-abdominal pressure. Other contributing factors (eg, trauma, malnutrition, urinary and vaginal infections, and urethral mucosa redundancy) have been postulated in the etiology of this condition. [8]



Most conditions discussed in this article are infrequent or rare.

Although the dorsal urethral diverticulum in the roof of the fossa navicularis (ie, lacuna magna) may be present in approximately 30% of examined boys, this condition is rarely symptomatic. 

Urethral duplications are rare; only 150 cases had been reported in the literature prior to 1986.

Each year, an estimated five of every 1000 boys (of all races and ethnicities) born in the United States have hypospadias, making it one of the most common birth defects. [9, 10]  It has been estimated that epispadias with exstrophy occurs about once every 30,000 births, isolated epispadias without exstrophy in males about once in 120,000, and isolated epispadias in females about once in 500,000. [11]

The ratio of the incidence of AUVs to that of PUVs is 1:8; PUV occurs in 1 in 8000 to 1 in 25,000 live male births.

Fewer than 50 cases of megalourethra had been reported in the literature by 1993; the scaphoid type is more common. Megalourethras have often been associated with other severe anomalies, such as prune belly syndrome, cloacal malformations, and the VACTERL (vertebral, anal, cardiac, tracheal, esophageal, renal, and limb) association of congenital anomalies.

Diverticula of the anterior urethra are uncommon but are the second most common form of congenital urethral obstruction, after PUVs, in infants and children. 

Both Cowper duct cysts and congenital urethral polyps are quite rare.

Urethral prolapse has an estimated incidence of 1 in 3000 and is most common in young black or Latin American girls.



Associated anomalies determine the prognosis of patients with fusiform megalourethra. Although obstructive lesions may be successfully managed with various operative techniques, prognosis ultimately depends on renal damage secondary to obstruction and infection.