Urethral Diverticula




(1)
Pediatric Surgery, Al Azher University, Cairo, Egypt

 



Abstract

Urethral diverticula are a tubular or spherical pouches opening in the urethral canal by means of an ostium at any point of its course. The congenital one called a true diverticulum. A urethral diverticulum is differentiated from other cystic structures like; urethral cysts and syringocele, as it is a permanent, epithelialized, non-muscular, sac-like cavity projecting into the periurethral fascia and arising from the urethral lumen.


Keywords
Urethral diverticulaProstatic utricleSaccular diverticulum



Definition

Urethral diverticula are a tubular or spherical pouches opening in the urethral canal by means of an ostium at any point of its course. The congenital one called a true diverticulum. A urethral diverticulum is differentiated from other cystic structures like; urethral cysts and syringocele, as it is a permanent, epithelialized, non-muscular, sac-like cavity projecting into the periurethral fascia and arising from the urethral lumen.


29.1 Historical Background


“Hey” described the first female urethral diverticulum in 1805. Since this initial report, urethral diverticulum has been diagnosed with increasing frequency. The first case report of congenital urethral diverticulum in a male child was described in 1906 by Watts [1].


29.2 Incidence


The frequency with which this disorder occurs is difficult to estimate due to the high probability of a substantial number of missed or misdiagnosed cases in any given population. An overall prevalence of urethral diverticula of 3 % was reported, with a great difference between males and females, as well as the age group of patients at the time of diagnosis [2]. Anterior urethral diverticulum, although uncommon, is the second most common cause of congenital urethral obstruction in boys after urethral valve, with an incidence of 1–6 % in the general population [3].

Despite the increased awareness in recent years, this entity continues to be overlooked during routine evaluation of children with voiding problems. Accurate diagnosis and treatment of urethral diverticula require a high index of suspicion and appropriate radiologic and endoscopic evaluations.


29.3 Etiology and Pathogenesis


It is thought that urethral diverticula may be either congenital or, acquired. There are no clear morphologic criteria to make this distinction. The majority of urethral diverticula in adults are acquired (as sequelae of infection, trauma, calculus or obstruction). Inflammation of a paraurethral or peri-urethral glands, where their ducts become infected repeatedly, they can become blocked and eventually cause a diverticulum. They are usually found in the middle or the distal urethra. Many cases of hypospadias may be complicated after inadequate repair with a diverticulum of different sizes (Fig. 29.1).

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Fig. 29.1
Acquired urethral diverticulum after hypospadias repair

Congenital urethral diverticula can arise from several embryological sources; include defects in the primordial folds and remnants of Gartner’s duct [3].

Most urethral diverticula are located posteriorly in the middle and distal urethra and are due to faulty closure of the urethral folds like hypospadias. The difference being that in diverticula the urethra alone is involved, whereas in hypospadias the defect extends through the skin. All congenital diverticula are situated on the ventral side of the anterior urethra and none in the posterior urethra. Pathologically, they are lined by mucous membrane similar to that of the urethra and their walls may contain a striated muscle layer [4]. A diverticulum of the anterior urethra develops on the ventral surface of the penile urethra as a result of either incomplete development of the corpus spongiosum focally or incomplete fusion of a segment of the urethral plate. A lip of tissue may be seen around the diverticulum. As the diverticulum distends, the lip of tissue is pressed against the urethral wall and results in a valve like obstruction.

A congenital obstructing anterior urethral valve leading to diverticulum formation has also been suggested. There are opinions that CAUD? and anterior urethral valves, possibly, represent the spectrum of the same disease.

The embryology of AUD? remains unclear. Various proposed hypotheses include a developmental defect of corpus spongiosum, cystic dilatation of the urethral glands and sequestration of an epithelial nest after closure of the urethral folds. With a focal lack of corpus spongiosum, a urethral dilatation in this region may develop into a diverticulum. Suter proposed the theory that a diverticulum of the urethra develops because of epidermal pockets communicating with the ventral urethral wall. As the anterior urethral tube forms, the urethral groove may leave behind epithelial cells that form a congenital cyst. Cysts in this region developing a communication with the urethra could lead to diverticulum formation as a result of the spontaneous rupture of the cyst into the urethral lumen [5]. In contrast to anterior urethral diverticula, which are primarily congenital, posterior urethral diverticula are generally of an acquired origin.


29.4 Classifications


There is controversy as to the classification of urethral diverticula. The most commonly used is that proposed by Watts in 1906, who divided them into congenital and acquired. The former involves the complete thickening of the urethral wall that is covered by epithelium, and the latter are covered by granulation tissue and their walls lack muscle fibres [1].

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Jun 30, 2017 | Posted by in UROLOGY | Comments Off on Urethral Diverticula
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