Urethral Diverticula

Updated: Dec 01, 2015
  • Author: Sandip P Vasavada, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Overview

Background

Urethral diverticulum in females is a localized outpouching of the urethra into the anterior vaginal wall. Most often present in the mid or distal urethra, urethral diverticula result from enlargement of obstructed periurethral glands.

Although urethral diverticulum is often difficult to diagnose, it has been identified with increasing frequency over the past several decades because of increased physician awareness of the condition. The most common symptoms associated with urethral diverticula include urinary frequency, urgency, and dysuria. In some cases, urethral carcinoma and calculi are also present.

Surgical excision is the treatment of choice for urethral diverticulum. With appropriate surgical management, cure rates are high, and recurrences are rare. [1, 2]

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History of the Procedure

Hey described the first female urethral diverticulum in 1805. Since this initial report, urethral diverticulum has been diagnosed with increasing frequency. Despite the increased awareness in recent years, this entity continues to be overlooked during routine evaluation of women with voiding problems.

Accurate diagnosis and treatment of urethral diverticula require a high index of suspicion and appropriate radiologic and endoscopic evaluations.

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Problem

Urethral diverticulum is defined as a localized outpouching of the urethra into the anterior vaginal wall.

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Epidemiology

Frequency

The incidence of female urethral diverticulum ranges from 1.4-5% but may be higher. The true incidence is unknown because many urethral diverticula are clinically asymptomatic.

Urethral diverticula occur most commonly in people aged 30-60 years. The mean age at diagnosis is 45 years. Occurrence in children is rare.

Although some reports have described a predilection for urethral diverticula in black women, this remains controversial.

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Etiology

Several theories have been proposed to explain the etiology of female urethral diverticulum.

Congenital urethral diverticula are rare; however, urethral diverticula in children have been used to support the congenital origin theory. Congenital urethral diverticula have been postulated to arise from the following:

  • Remnant of Gartner duct
  • Faulty union of primordial folds
  • Cell rests
  • Vaginal wall cysts of müllerian origin
  • Congenital dilatation of periurethral cysts
  • Association with blind ending ureters

Most authors suggest that most urethral diverticula are acquired. Potential theorized causes of acquired urethral diverticula include vaginal birth trauma, urethroscopy, urethrotomy, and various open surgical procedures. However, these theories have largely been abandoned. The most widely accepted theory implicates repeated infections of the periurethral glands with subsequent obstruction eventually evolving into urethral diverticula.

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Pathophysiology

Tubuloalveolar mucous glands, known as periurethral glands, line the urethral wall. They are located posterolaterally in the mid and distal third of the urethra. Most periurethral glands drain into the distal urethra.

When periurethral glands become infected, they may become obstructed. Repeated infections lead to increasing obstruction of the gland and result in periurethral gland enlargement into a suburethral cyst or an abscess cavity. Eventually, the cavity ruptures into the urethral lumen, creating a communication between the urethral lumen and the suburethral cyst. Repeated pooling of urine into the suburethral cyst during urination leads to the formation of a urethral diverticulum.

Urethral diverticula commonly occur in the distal third of the urethra. Although uncommon, distal urethral diverticula may also originate from an obstructed Skene gland. Rarely, urethral diverticula occur in the anterior urethra or its proximal third.

Pathologically, the diverticulum is a urethral evagination that consists of mostly fibrous tissue. Often, an epithelial lining is absent. The chronic inflammation within the diverticulum results in marked fibrosis and adherence of the diverticular wall to the neighboring structures.

Surrounding periurethral fascia often remains intact. However, a severely infected urethral diverticulum may result in spontaneous erosion into the vagina.

Urethral diverticula vary in size, shape, and communication with the urethra. They may be unilocular or multilocular. Some are spherical (see image below), and others are horseshoe shaped. The diverticular opening into the urethral lumen may be very narrow or extremely wide.

The urethral diverticulum is shown as spherical ma The urethral diverticulum is shown as spherical mass at the distal urethra.

Although different types of pathogens have been cultured from the diverticulum, the most commonly identified pathogens include Escherichia coli, Chlamydia species, and, rarely gonococci.

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Presentation

History

Presenting symptoms of urethral diverticula are classically described as the triad of postvoid dribbling, dysuria, and dyspareunia (known as the 3 D s). However, the symptoms of urethral diverticula vary significantly. Owing to the variety of presenting symptoms, urethral diverticula are known to be delayed in diagnosis and one must have a high index of suspicion for this entity to ultimately discover it.

Irritative voiding symptoms, such as urinary frequency, urgency, and dysuria, are most common. Recurrent urinary tract infections occur in approximately 40% of patients, whereas approximately 25% report postvoid dribbling, and approximately 10% report dyspareunia. Other less frequent symptoms include hematuria and an anterior vaginal wall mass.

Symptoms of urethral diverticulum can often be confused with other disorders such as interstitial cystitis, overactive bladder, and carcinoma in situ. Patients who have irritative voiding symptoms that do not respond to medical therapy should trigger a high index of suspicion for urethral diverticulum. Interestingly, many urethral diverticula are completely asymptomatic and are discovered incidentally.

Approximately one third of patients with urethral diverticula present with recurrent urinary tract infections. Chronically infected diverticula may demonstrate no other associated symptoms except for recurrent urinary tract infections. At times, the infected diverticulum may progress to an abscess, requiring transvaginal aspiration.

Physical examination

A careful pelvic examination frequently reveals the suburethral mass on the anterior vaginal wall. The differential diagnoses of an anterior vaginal wall mass should include urethral diverticulum, Skene gland abscess, ectopic ureterocele, Gartner duct cyst, müllerian remnant cyst, and vaginal inclusion cyst.

Palpation of the anterior vaginal wall may reveal a soft spherical mass, which is often exquisitely tender. Compression of the mass may express urine or purulent material from the external meatus. Distinct firmness or hardness may reflect the presence of a stone or neoplasm within the diverticulum.

Stress urinary incontinence may coexist with urethral diverticula. The pelvic examination should also include careful assessment of urethral hypermobility and vaginal prolapse. The presence of stress incontinence or vaginal prolapse should be noted prior to surgery because either may require simultaneous repair at the time of diverticulectomy.

Once a diagnosis is suspected based on history and physical examination findings, endoscopic and radiologic studies help to localize the diverticulum.

Female urethral diverticula may be complicated by infection, stones, bladder outlet obstruction, and malignancy. Infection may be acute or chronic and may result in abscess formation.

Stone formation within urethral diverticula is reported to occur in 1-10% of patients. When proximal urethral diverticula become very large, they can obstruct the bladder outlet, causing acute urinary retention. [3]

Urethral carcinoma is a rare complication of urethral diverticula. Although squamous cell carcinoma is the most common histologic type of female urethral malignancy, adenocarcinoma is by far the most common cancer associated with urethral diverticula. This type of cancer found within diverticula likely represents the cell of origin of most diverticula (being glandular). Nephrogenic adenoma and endometriosis have also been reported in association with female urethral diverticula. [4]

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Indications

Surgical correction of urethral diverticula is indicated in patients with significant symptoms, including recurrent urinary tract infections, severe pain, dyspareunia, frequency, urgency, and postvoid dribbling.

Additional indications for surgery include urethral calculi, urinary retention, and carcinoma.

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Relevant Anatomy

The adult female urethra is approximately 4 cm long and traverses the bladder neck to the external meatus. The mucosa of the female urethra is lined by transitional cell epithelium that gradually changes to nonkeratinizing squamous epithelium from the bladder neck to the external urethral meatus.

Small periurethral secretory glands interdigitate the wall of the urethra to produce lubrication for the inner mucosa. These periurethral glands converge at the distal urethra as Skene glands and empty through 2 small ducts on either side of the external meatus.

Repeated bouts of infection and occlusion of the periurethral glands lead to formation of suburethral cysts. These suburethral cysts enlarge and eventually rupture into the urethral lumen. During urination, constant pooling of urine within these cysts gives rise to urethral diverticula (see image below).

Voiding cystourethrogram reveals contrast pooling Voiding cystourethrogram reveals contrast pooling in a urethral diverticulum. The urethral diverticulum is located well away from the bladder neck at the distal urethra.

The submucosa of the female urethra is a rich vascular network of spongy tissue. The submucosal layer nourishes the urethral epithelium and the underlying mucous glands. Both the mucosa and the submucosa are responsible for providing a part of the continence mechanism—the mucosal seal.

The mucosal epithelium and the submucosal vascular plexus are highly responsive to estrogen. Loss of estrogen at menopause may result in atrophy or loss of the mucosal seal, causing intrinsic sphincteric deficiency. Intrinsic sphincter deficiency is a complex form of stress urinary incontinence.

The urethra contains 2 layers of smooth muscle: the inner longitudinal layer and an outer circular-oblique layer. The inner longitudinal smooth muscle layer is the thicker of the two and continues from the bladder neck to the external meatus. The outer circular-oblique smooth muscle layer encases the longitudinal fibers throughout the length of the urethra. Normally, the inner and the outer smooth muscle layers are adherent via strong connective tissue fibers. The separation of these layers leads to complete urethral prolapse.

The female bladder neck is an internal sphincter but possesses little adrenergic innervation and has limited sphincteric action. The striated urethral sphincter is composed of delicate type I (slow-twitch) and type II (fast-twitch) skeletal muscle fibers surrounded by abundant collagen. It forms a complete ring around the proximal urethra to provide the zone of highest urethral closure pressure. The striated urethral sphincter receives dual somatic innervation from the pudendal and pelvic somatic nerves.

Little sympathetic innervation is found in the female urethra, but parasympathetic cholinergic fibers are found throughout the smooth muscle fibers. Activation of the parasympathetic fibers causes the inner longitudinal smooth muscle of the urethra to contract in synchrony with the detrusor. Contraction of the longitudinal fibers shortens and widens the urethra to allow normal urination.

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Contraindications

Active infection of the urinary tract or the diverticulum precludes surgical intervention until the infection is eradicated. The presence of a urethral abscess may require transvaginal aspiration or incision and drainage under examination or with ultrasonographic guidance prior to definitive therapy.

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