Q. A 44-year-old woman is referred from her GP with a history of recurrent UTIs. Bimanual inspection reveals a tender mass on the anterior vaginal wall. What is your differential diagnosis?
A. The differential diagnoses include
Urethral diverticulum
Skene’s gland cyst or abscess
Gartner’s duct cyst
Ectopic ureterocele
Vaginal inclusion cyst
Urethral or vaginal malignancy
Q. What is the pathogenesis of female urethral diverticula (UD)?
A. The causes of urethral diverticulum are not fully established; the most widely accepted theory is that they occur secondary to infection of the periurethral glands. The periurethral glands are tubular alveolar structures located posterolaterally to the periurethral fascia. They are found in the proximal two-thirds of the urethra and drain into the distal third. Infection leads to obstruction of the glands, local abscess formation and eventual rupture into the urethral lumen.
Q. How do female UD present?
A. Classically a urethral diverticulum was suspected if a woman presented with the triad of dysuria, post-void dribbling and dyspareunia. However, studies report a much broader spectrum of symptoms. According to a recent series up to 77% of cases would have been missed if the clinician relied upon this triad alone to make the diagnosis [9]. In reality patients present symptoms as shown in Table 11.3 [10].
Q. How would you investigate a potential urethral diverticulum?
A. Clinical examination and cystoscopic evaluation - A zero or 30° urethroscope is used, the anterior vaginal wall is compressed with a finger in the vagina and the urethral lumen is inspected for any expressed pus from the floor or the roof of the urethra. However often the os can be hidden between collapsed urethral folds and cystoscopy does not give any information about the size or shape or appearance of the diverticular wall.
VCUG - Voiding cystourethrogram is an invasive test which involves the use of ionizing radiation but has a sensitivity of 65% There fore further investigations are usually required.
Ultrasonography - Use of ultrasound has been described either transvaginally or trans- rectally but this investigation is operator dependent.
Magnetic resonance imaging (MRI) - MRI is the current gold standard in diagnostic imaging for UD. Endorectal or endovaginal coil MRI techniques differ from surface or body-coil techniques as the coil is placed within the body cavity adjacent to the tissue of interest; this leads to higher-resolution imaging of the urethra. Up to 100% sensitivity has been reported when MRI is used for the detection of UD. The signal intensity of fluid is high on the T2-weighted images. In addition MRI provides information on the size, location and complexity of the diverticulum allowing accurate surgical planning.
Retrograde positive-pressure urethrography - Reported to have a 90% diagnostic accuracy but is rarely used in current urological practice. It is an uncomfortable procedure and is technically difficult requiring a special catheter (Davis or Tratner catheter) which has a double balloon. One balloon is placed in the bladder. The distal balloon slides to occlude the external meatus during injection of contrast via ports located between the balloons.
Table 11.3 Presentations of urethral diverticulum
|
Frequency/urgency |
40%-100% |
|
Dysuria |
30%-70% |
|
Recurrent UTI |
30%-50% |
|
Post-micturition dribble |
10%-30% |
|
Dyspareunia |
10%-25% |
|
Haematuria |
10%-25% |
Q. What are the principles of repair of a female urethral diverticulum?
A. The key steps in the repair of the diverticulum are the following:
Mobilisation of a well-vascularised anterior vaginal wall flap (or flaps)
Preservation of periurethral fascia
Identification and excision of the neck of the urethral diverticulum or ostia
Remove of entire urethral diverticulum wall or sac (mucosa)
Watertight urethral closure
Multilayered, non-overlapping closure with absorbable sutures (Martius flap graft)
Closure of dead space
Preservation or creation of continence
Q. What are the principles of a Martius flap graft?
A. The Martius graft is a long band of adipose tissue taken from the labia majora, it has excellent strength and vascularity, its blood supply is threefold. Branches of the external pudendal supply the graft superiorly and anteriorly, obturator branches enter the graft at its lateral border. The inferior labial artery and vein supply the graft inferiorly; hence the graft may be mobilised superiorly or inferiorly depending upon the desired location of transfer.
Q. What are the possible complications of urethral diverticulum repair?
A. The complications are as follows:
Urinary incontinence
Urethrovaginal fistula
Urethral stricture,
Recurrent urethral diverticulum
Recurrent UTI
Bladder/ureteric injury
Vaginal scarring/narrowing leading to dyspareunia