Urethral Diverticula

Practice Essentials

Urethral diverticulum (UD) 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. 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.

Treatment options for UD can range from conservative management to extensive surgery, most commonly diverticulectomy.^[1]  Patients with pre-existing stress incontinence may receive concomitant autologous pubovaginal sling (APVS) placement at the time of diverticulectomy.^[2]  

For patient education resources, see the Kidneys and Urinary System Center, as well as Bladder Control Problems.

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Relevant Anatomy

The adult female urethra is approximately 4 cm long and extends from 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).

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

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, which 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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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.

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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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Etiology

Several theories have been proposed to explain the etiology of female urethral diverticulum. They encompass congenital and acquired causes.

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

Acquired diverticula may originate from repeated urinary tract infections obstructing the periurethral glands; these can then rupture into the urethral lumen, creating local herniation. Another theory posits that an obstructed periurethral gland becomes infected and develops into an abscess that ruptures into the urethral lumen, forming an ostium.^[3]

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Epidemiology

Frequency

Female urethral diverticulum (UD) is a rare disorder with an annual incidence of 17.9 per 1,000,000 (0.02%) per year.^[1]  UD is thought to represent 1.4% of women with incontinence presenting to urology practices.^[4]  Urethral diverticula occur most commonly in people aged 30-60 years. The mean age at diagnosis is 45 years. Occurrence in children is rare.

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Prognosis

As a consequence of delayed diagnosis, women may encounter several complications, such as recurrent urinary tract infections, stone formation, and more rarely, malignancy.^[1]

Although pathology is benign 97% of the time a high degree of suspicion is needed in the case of a firm mass or if MRI indicates a mass within the diverticula.^[5]  Diverticula frequently contain a thick wall or multiple septa and favor the potential development of adenocarcinoma. In a small series to evaluate the MRI findings differentiating clear cell adenocarcinoma of the urethra (CCAU) from nonadenocarcinoma of the urethra (NACU) and non–clear cell adenocarcinoma of the urethra (NCCAU) in women, all  six cases of CCAU were associated with a urethral diverticulum. Periurethral or paraurethral glands are located among the inner longitudinal muscles, and it has been postulated that tumors arising from urethral diverticula may dissect the urethral muscle layer.^[6]

Surgical excision of the diverticulum continues to be the mainstay of treatment with most studies reporting cure rates of >90%.^[4]  Complications reported in the literature include the following:

• Recurrent diverticulum (1-29%)
• Stress incontinence (1.7-16%)
• Urethral stricture (0-5%)
• Recurrent urinary tract infection (0-31%)

Multiple diverticula, proximal diverticula and previous urethral surgery were three independent risk factors for recurrent diverticula.^[7]

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History

Presenting symptoms of urethral diverticula are classically described as the triad of postvoid dribbling, dysuria, and dyspareunia (known as the 3Ds). However, the symptoms of urethral diverticula vary significantly. The most common presentations of urethral diverticula are as follows^[8] :

• Recurrent urinary tract infections (70%)
• Stress urinary incontinence (60%)
• Dyspareunia (60%)
• Vaginal mass (52%) 

Irritative voiding symptoms that do not respond to medical therapy should trigger a high index of suspicion for urethral diverticulum. However, many urethral diverticula produce no symptoms and are discovered incidentally.

Patients with 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.

Owing to the variety of presenting symptoms, diagnosis of urethral diverticula is often delayed. A high index of suspicion for this entity is required.

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Physical Examination

A careful pelvic examination frequently reveals the suburethral mass on the anterior vaginal wall. 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.

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.^[9]

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.^[6] 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.^[10]

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Approach Considerations

Once a diagnosis is suspected based on history and physical examination findings, endoscopic and radiologic studies help to localize the diverticulum. Urine culture should be performed to exclude coexisting urinary tract infection.  When possible, obtain culture of the expressed fluid from the diverticulum, as this aids in appropriate antibiotic selection.

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Imaging Studies

The principal imaging studies used in the workup of urethral diverticula are voiding cystourethrography (VCUG) and magnetic resonance imaging (MRI). Infrequently used techniques that may have utility in selected cases include intravenous pyelography (IVP), computed tomography (CT) urography, and retrograde urethrography using a double-balloon catheter. 

Voiding cystourethrography

The most helpful plain film radiologic study is properly performed VCUG. This study aids in defining the location, size, and number of diverticula present. The study should be performed under fluoroscopic control with the patient sitting or standing in an oblique position.  The presence of filling defects within the diverticulum may suggest the possibility of urethral calculi or a tumor.

MRI 

This imaging study has emerged as the criterion standard in diagnostic imaging for urethral diverticula, as it reveals the extent and location of the diverticula.^[5] In patients with strongly suspect symptoms, MRI demonstrates the diverticulum with the highest sensitivity and specificity of any of the imaging modalities. Furthermore, planar technology allows the exact ostium to be identified prospectively in many cases and can give the operating surgeon a “roadmap” from which to guide the operative intervention.^{[11, 12]}

Intravenous pyelography and CT urography

Urethral diverticula have been noted incidentally on IVP relatively infrequently.  Postvoid radiography from an IVP may reveal a collection of contrast below the urinary bladder consistent with urethral diverticulum.

While IVP is not recommended as a routine imaging study to document urethral diverticulum, it is useful when ectopic ureterocele is suspected. CT urography may be a better modality since it offers more planes of view; however, no studies to date have confirmed it should be used routinely in the evaluation of suspect diverticula.

Retrograde urethrography using a double-balloon catheter

This technique has been popular in the past but has fallen out favor because retrograde positive-pressure urethrography is technically difficult to perform and is usually painful. However, this procedure may be performed under general anesthesia, if desired. This procedure has largely been replaced by MRI. Retrograde urethrography using a double-balloon catheter may be useful if a suspected diverticulum cannot be observed on a VCUG.

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Procedures

Urodynamics

Consider urodynamic studies in patients with symptoms of stress urinary incontinence or overactive bladder.  Patients with overactive bladder may require anticholinergic therapy to control irritative voiding symptoms.

Cystoscopy

Cystourethroscopy is often performed using a short beaked female urethroscope with a 0° lens. Alternatively, flexible cystoscopy or a urethrotome sheath may be used. Constant water flow and bladder neck occlusion during urethroscopy allows the entire urethra to be distended to enhance visualization. Simultaneous digital compression of the urethral diverticulum may cause active drainage of pus into the urethral lumen, allowing identification of the communication site.

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Approach Considerations

To date, no known medical therapy exists for successful treatment of urethral diverticulum. Long-term low-dose antibiotic therapy may allow resolution of localized symptoms, but the anatomic abnormality remains. Surgery is the current treatment of choice.  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.

Treat infected urethral diverticula with appropriate antibiotics prior to surgery. 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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Surgical Therapy

Multiple open surgical and endoscopic approaches have been described for the treatment of urethral diverticula, including the following^[13] :

• Transurethral saucerization of the diverticulum
• Marsupialization of the diverticular sac into the vagina
• Excision of the diverticulum

Transurethral saucerization of the urethral diverticulum involves incising the opening of the diverticulum to convert a narrow neck into a wide neck. In general, reserve this for distal diverticula because more proximal incision of the urethral wall may compromise continence.

The marsupialization of a diverticulum is performed by incising the urethrovaginal septum. It is essentially a generous meatotomy, which may result in vaginal voiding. As with endoscopic saucerization, overzealous incision or treatment of mid or proximal diverticula with this technique may result in urinary incontinence. This technique should be reserved for distal diverticula, although definitive reconstruction likely yields a better functional outcome. Distal marsupialization may lead to spraying of the urine stream and dyspareunia.

Numerous techniques are available for transvaginal excision. A popular transvaginal technique uses a vaginal flap. This technique allows complete excision of the diverticulum, closure of the urethral communication, reinforced coverage with periurethral fascia, and closure of the anterior vaginal wall. It allows a secure 3-layer closure without overlapping suture lines. See intraoperative images below.

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The anterior vaginal wall and the periurethral fascia have been dissected off, exposing the urethral diverticulum.

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The urethral diverticulum has been excised sharply. Foley catheter is visible through the neck of the diverticulum.

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The urethral diverticulum is closed in 3 layers with nonoverlapping suture lines. The vaginal wall is closed.

Concomitant treatment of preexisting stress incontinence with autologous fascial pubovaginal sling can be used at the time of diverticulectomy to avoid a secondary procedure. However, since secondary anti-incontinence procedures are needed in only a small number of patients, up-front stress incontinence treatment may result in significant overtreatment, and staged anti-incontinence procedures continue to be a reasonable option for patients with persistent bothersome stress urinary incontinence (SUI) after diverticulectomy.^[4]

Prior to surgery, proper antibiotic therapy is mandatory. Reconstructive surgery in a patient with active urinary and diverticular infection may lead to urethrovaginal fistula formation or recurrent diverticula. Preoperative counseling should include discussion of possible complications such as infection, bleeding, recurrent diverticulum, urethrovaginal fistula, and urinary incontinence.

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Intraoperative Details

After general anesthesia is induced, place the patient in the lithotomy position. Sterilely prepare and drape the lower abdomen and genitalia. A percutaneous suprapubic catheter is often placed; many surgeons forego the suprapubic tube. After infiltrating the anterior vaginal wall with sodium chloride solution, make a U-shaped incision.

Mobilize the anterior vaginal wall flap to expose the diverticulum. Take care to prevent premature violation of the periurethral fascia or the diverticulum.

Transversely incise the periurethral fascia. Develop proximal and distal flaps of periurethral fascia and reflect them off the underlying diverticulum.

Dissect the diverticulum circumferentially down to its urethral communication and excise it completely. In the case of a very large diverticulum, the proximal portion may be left and the inner surface electrocauterized to destroy any epithelial elements.

Close the urethral defect vertically without tension using a running 3-0 or 4-0 absorbable suture incorporating both mucosal and muscular layers of the urethral wall.

Transversely reapproximate the periurethral fascia with a 2-0 or 3-0 absorbable suture constituting the second layer of closure to ensure that no dead space is left over the urethral repair. Planned interposition of a biological sling or Martius flap is performed before the third layer is started. The third layer of closure is the vaginal wall, which is closed with a running 2-0 absorbable suture.

Place an antibiotic-soaked vaginal pack and place both the suprapubic and urethral catheters to sterile drainage. The use of routine suprapubic tube drainage is left to surgeon discretion, but most experts have reserved suprapubic tube drainage for larger or more complex and extensive diverticula.

Important factors in operative success include precise anatomic dissection, a watertight closure, and closure in multiple layers. Avoid overlapping suture lines.

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Postoperative Details

Continue intravenous antibiotics for 24 hours postoperatively, followed by oral antibiotics until the catheters are removed. Belladonna and opium (B&O) suppositories or oral anticholinergics prevent bladder spasms.

The morning after the operation, remove the vaginal packing. The patient is usually discharged home the following day with both catheters still indwelling.

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Follow-up

Perform voiding cystourethrography 10-14 days postoperatively. Discontinue anticholinergics 24 hours before the voiding study. Remove the urethral catheter and instill the contrast into the bladder via the suprapubic catheter. If the surgeon elected not to place a suprapubic catheter, then place the contrast via the urethral catheter.

Carefully observe the urethra fluoroscopically during voiding. If no extravasation is observed and the patient empties the bladder to completion, remove the suprapubic tube. If the postvoid residual is more than 100 mL, leave the suprapubic catheter in place, intermittently unclamping it to drain the residual urine and perform residual urine checks until the bladder is satisfactorily emptying.

Some patients may present with extravasation during the first voiding study. If extravasation is observed, ideally more time is given to achieve optimal healing so the suprapubic catheter is placed to gravity drainage. Do not replace the urethral catheter. Perform repeat voiding cystourethrography in 7-10 days.

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Complications

Patients with active diverticular infection may experience profuse bleeding during vaginal dissection. A large defect created during excision of a large diverticulum may result in urethral strictures. A large proximal diverticulum that extends under the trigone and bladder neck may result in the risk of ureteric injury. Operating on patients with active infection may lead to fistula formation. Urethrovaginal fistula formation is the most difficult complication of diverticular surgery. If it occurs, repair the fistula after an adequate period of healing, but usually several weeks to 3 months minimum healing should suffice.

Anterior vaginal infection is unusual but responds well to antibiotics. If a suburethral abscess forms, surgical drainage is required. If urethral diverticulum recurs, perform secondary surgery after a prudent period of observation. Secondary stress incontinence not present prior to surgical therapy may develop and is more likely in patients who undergo extensive dissection of the urethral wall or its lateral attachments or in the setting of large or proximal diverticula.

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