Dorsal urethroplasty with labia minora skin graft for female urethral strictures

Authors


Peter Rehder, Department of Urology, Medical University Innsbruck, Austria, Anichstrasse 35, 6020 Innsbruck, Austria.
e-mail: peter.rehder@i-med.ac.at

Abstract

Study Type – Therapy (case series)
Level of Evidence 4

OBJECTIVE

To report a new dorsal labia minora skin-graft urethroplasty as a simple, safe and effective therapeutic alternative for female urethral strictures, as although distal urethral strictures can be treated by meatoplasty, proximal and mid-urethral strictures need appropriate urethroplasty.

PATIENTS AND METHODS

Eight women with a confirmed proximal or mid-urethral stricture had indications for urethroplasty with the use of a thin free labia minora skin graft using a dorsal (6 o’clock position) urethroplasty technique. Full informed consent was obtained. From the inner aspect of one labium minora a thin free skin flap was prepared. The strictured urethra and the anterior vaginal wall were transected and the graft sutured into the defect. All scar tissue was removed and the anterior vaginal wall closed in two layers over the area of the urethroplasty. Continence was evaluated by a stress test with a full bladder.

RESULTS

All patients were operated on with no complications during or after surgery. After 1 and 2 years of follow-up seven and six of the eight patients had no recurrence of stricture disease. All patients remained continent.

CONCLUSION

The urethroplasty using an inlay of free thin genital skin graft was safe, uncomplicated and effective.

Abbreviations
VCUG

voiding cysto-urethrography

Qmax

maximum urinary flow rate.

INTRODUCTION

A female urethral stricture is a rare entity, with an incidence of only 13% in women with BOO, and its aetiology is controversial; it seems that most cases are iatrogenic, traumatic or congenital. Typically women present with symptoms of frequency and urgency, poor stream or dribbling, with additional complaints of dysuria and recurrent UTIs [1].

Several methods of repair have been reported. It seems reasonable to make an initial attempt at conservative management for short female urethral strictures, via dilatation or urethrotomy. Distal urethral strictures in females can be managed by meatoplasty. If there is a recurrence, an open repair (urethroplasty) should be performed. Various urethroplasty techniques, using different flaps or buccal mucosa grafts, have been described and shown to be successful in small series of patients [1–4].

In the present study we report our experience of using a dorsal labium minora thin skin graft urethroplasty in women with recurrent proximal or mid-urethral strictures.

PATIENTS AND METHODS

Eight women (men age 45 years, range 28–67) with recurrent symptomatic urethral strictures underwent urethral reconstruction using a labia minora skin graft for the dorsal urethroplasty. All patients had a preoperative evaluation including a detailed history and physical examination, complete urodynamic evaluation, voiding cysto-urethrography (VCUG) and cysto-urethroscopy, after careful urethral dilatation when necessary. The diagnosis was based on the following criteria: a maximum urinary flow rate (Qmax) of <12–15 mL/s and a bladder pressure of >30 cmH2O during voiding, calibration of the urethral lumen at <14 F (in this series); evidence of urethral stricture at VCUG, with widening of the proximal urethra (Figs 1,2), and the findings of urethral narrowing on cysto-urethroscopy. All patients complained of preoperative recurrent UTI, straining and a burning sensation during voiding, terminal dribbling and decreased flow. All patients were assessed using transvaginal ultrasonography (difficult) and/or MRI. Full informed consent was obtained after explaining all the different techniques of urethroplasty (dorsal, ventral, buccal mucosa, skin grafts and flaps). Ethical committee approval for a retrospective analysis was obtained.

Figure 1.

Preoperative VCUG showing the widened proximal urethra with mid-urethral narrowing.

Figure 2.

VCUG showing the normal wide urethra at 3 weeks after urethroplasty.

In the female urethra, and for the membranous urethra in males, the dorsal aspect of the urethra is the 6 o’clock position, i.e. close to the anterior vaginal wall or anal canal. The bulbo-penile urethra in males is described in the anatomical position, thus ‘dorsal’ meaning the 12 o’clock position as seen by retrograde urethroscopy in the lithotomy position. Various reports have used the latter also for describing the membranous urethra, causing some confusion. In this report the membranous and the female urethra is described referring to dorsal (6 o’clock, close to vagina, posterior) and ventral (12 o’clock position, close to the symphysis, anterior).

For the surgical technique, the patient is placed in the dorsal lithotomy position. The operative field, including the vagina, is cleaned with iodine solution and draped. The anus is adequately covered and sealed from the wound area. The labia minora are retracted laterally with the help of stay sutures. Next, the urethral meatus and urethra are investigated by a urethral probe to confirm the stricture. An incision is made at the 6 o’clock position of the urethral meatus to include the dorsal (posterior) urethral wall, periurethral tissue and anterior vaginal wall. This incision is continued proximally along the urethra until the whole length of the stricture is widely spatulated. If the urethra is very fibrosed then the anterior vaginal wall is infiltrated with normal saline to facilitate dissection. The anterior vaginal wall is only opened as far as is necessary for proper suturing, i.e. enabling proper urethral spatulation. Further proximal urethral wall transection was then carried out leaving the vaginal wall intact. Care was taken to leave the bladder neck intact. At this stage the urethra is opened far enough to clearly see the extent of the stricture, and the anterior vaginal wall is carefully mobilized off the urethra. If the whole urethra is scarred then the whole length of the urethra is opened distally towards the bladder neck proximally in the 6 o’clock position. In this case the vaginal wall covering the bladder neck is not incised, to avoid destabilizing the bladder outlet. The omega-shaped striated sphincter inserts on the anterior vaginal wall and the dorsal midline of the sphincter consists mainly of fibrous tissue, minimizing the risk of incontinence. From the inside of one minor labium a thin patch of full-thickness skin is taken (Fig. 3). The flap is stretched on a board with needles and cleared of all remaining subcutaneous tissues, so as to create a thin skin graft. This free flap is perforated with a number 11 blade, to allow wound secretion to cross the skin flap after suturing it into the urethra. The skin defect on the labium is closed by primary suture with resorbable subcutaneous sutures. A diamond-shaped free flap is fashioned at least a third larger than the stricture length, to allow for postoperative shrinkage that might occur during healing. With the help of stay sutures the flap is sewn into position (Fig. 4). Interrupted 5/0 or 6/0 monophilic sutures are used proximally and distally, and continuous sutures for the lateral anastomosis of the inlay. The strictured area is now widened by the inlay, and the inlay is also fixed to the anterior vaginal wall, which is approximated over the urethra (Fig. 5). The vaginal wall is closed in layers, carefully approximating the mobilized tissues. The vaginal skin is closed with interrupted mattress sutures. No drains are placed, and a vaginal tampon is inserted for 2 days to prevent haematoma formation around the urethra. A 18–20 F corrugated transurethral Foley catheter is used to stent the urethra, and to drain the bladder, for 3 weeks. A few days relative bed rest is recommended to prevent unnecessary tensioning of the catheter over the wound area caused by walking. An oestrogen cream is recommended to optimize healing, especially in older women.

Figure 3.

Marking the 3-cm long free thin skin flap on the inside of the labium minora.

Figure 4.

The free thin skin graft is sutured dorsally into position in the spatulated urethra.

Figure 5.

With the transurethral catheter in-situ the thin skin graft is clearly apparent, in the area of the previous urethral stricture.

Patients were seen 3 weeks after surgery for VCUG, and an assessment by cysto-urethroscopy after 6 months. After 12 months all patients were evaluated with the same tests as used before surgery. When the patients were free of recurrent stricture disease for 1 year they received annual dates for follow-up with at least a urinary flow rate estimate, urine check and, when needed, urethroscopy and urethral calibration. Continence was evaluated with a stress test. The patient was asked to cough while upright and in the lithotomy position with a full bladder, i.e. ≥250 mL bladder filling as measured by a bladder scan. Furthermore, the patients were asked whether they needed pads during activity in the absence of menstruation. Statistical analysis of the results was based on Student’s t-test for paired data.

RESULTS

All eight patients had proximal or mid-urethral strictures, and all received previous urethral dilatation and/or longer periods of transurethral catheterization. One patient had a previous meatoplasty with recurrent stricture formation shortly afterwards.

In all patients the operation was completed with no complications. The mean stricture length was 16 mm and the mean patch length was 32 mm. At the first follow-up at 3 weeks after surgery VCUG (with catheter removal) showed a good urethral shape with no urinary leakage and no postvoid residual urine. Cysto-urethroscopy after 6 months showed in all cases a wide urethra with patency of the urethroplasty. At the 1-year follow-up, seven of the eight patients reported a significant improvement in voiding symptoms and all were continent. The mean (sd) urodynamic values before vs after surgery were: Qmax 12.3 (2.3) vs 39 (2.8) mL/s (P < 0.001); detrusor pressure at Qmax 42 (4) vs 18 (3) cmH2O (P < 0.001); and residual urine volume 180 (29) vs 20 (11) mL (P < 0.001). One patient reported recurrent UTIs and LUTS at 9 months after surgery. On cysto-urethroscopy a urethral meatal stenosis distal to the initial reconstruction was detected. The patient was treated with a meatotomy and was asymptomatic thereafter. None of the patients reported urinary incontinence after surgery. One patient developed extensive primary peritoneal carcinomatosis at 2 years after urethroplasty. She received maximum chemotherapy and after repeated catheterization had a recurrent stricture in the proximal to mid-urethra, needing another urethroplasty.

DISCUSSION

Female urethral strictures are a rare subset of the relatively uncommon female BOO syndrome. Most patients describe irritative and obstructive voiding symptoms. Apart from previous recurrent urethral dilatations, no specific cause for the urethral stricture disease could be identified. It was previously common practice for urologists to perform urethral dilatation in female patients with severe recurrent UTIs. Whether the UTIs or the urethral dilatations were causing subsequent urethral strictures is unclear. The results of urodynamic testing vary greatly between patients, but typically show Qmax values of <12–15 mL/s and detrusor pressure at Qmax of ≥30 cmH2O. Therefore video-urodynamics might assist in the diagnosis, and the imaging study of choice is VCUG. Several methods of therapy have been described. If the patient is treated for the first time a careful dilatation or urethrotomy can be used. However, both methods can exacerbate periurethral fibrosis, and recurrence rates are high. Urethral stricture recurrence should be treated with open repair, preferably at a facility with experience in urethroplasty using various flaps or buccal mucosa grafts [1–4].

In this pilot study we present a new method of urethroplasty using a dorsal labia minora thin skin graft. The good results with success in seven of eight patients after a 1-year follow-up support our concept. Even after a median follow-up of >2 years six of the eight patients had no recurrent stricture disease. We believe that as the bulk of the urinary female sphincter is shaped like a half-moon (omega-shaped) with insertion of the muscle fibres onto the midline raphe of the anterior vaginal wall, there is no danger of transecting any muscle fibres when cutting through the sphincter complex in the 6 o’clock position. The dorsal labia minora thin skin graft is placed in this position, after which the anterior vaginal wall structures are carefully approximated in two layers.

As the buccal mucosa graft has been used for successful urethroplasty in male patients, several groups have applied this technique to female urethral strictures [1,5,6]. Buccal mucosa is considered an excellent graft material as it is hairless, accustomed to a moist environment, and elastic. We believe that the thin skin graft of the labia minora is equally promising. A good blood supply of the donor bed is critical to success. Scar tissue should be excised and it might be necessary to mobilize the anterior vaginal wall laterally to be able to properly cover the inlay. As the donor site is close to the recipient site, it is believed that the structure and characteristics of the skin and mucous membranes are very similar, helping to support good healing with a minimal amount of scarring. Classically an inverted ‘U-shaped’ incision was used to create a proper covering for the area of the urethroplasty at wound closure. We decided to make a midline incision, as the blood supply and drainage is mainly lateral. When the ‘U-shaped’ vaginal flap was too narrow in the past, there was a tendency towards distal necrosis and/or scar-tissue formation, compromising the long-term outcome. To ensure proper wound covering using a length-wise incision, the vaginal wall should be carefully mobilized laterally and sutured back in layers using interrupted mattress sutures for the vaginal skin. No amount of unnecessary vaginal skin should be excised.

Berglund et al.[5] described two patients who received a ‘ventral’ (close to the vagina) buccal graft urethroplasty. The urethra was exposed through a midline anterior vaginal incision. The stricture was incised along its ‘ventral’ surface and the graft sutured in place. The repair was covered with healthy periurethral tissue. After surgery one of the two patients developed a recurrence of LUTS because of a meatal stenosis.

Migliari et al.[6] reported a similar procedure using buccal mucosa in three women, with the graft placed in a ‘dorsal’ (close to the symphysis) position. They reported that the ‘dorsal’ approach avoids graft weakening due to diverticula, decreases the risk of fistula and leads to more physiological voiding because the urinary stream is directed upward and not toward the vagina. They further stated that another positive aspect of the ‘dorsal’ urethroplasty is that it maintains the ‘ventral’ part of the mid urethra intact, leaving the possibility of an anti-incontinence procedure on the mid-urethra. In the present study none of the patients developed diverticula or fistula, the urinary stream was completely physiological and all the patients were continent. We believe that after 6–12 months of healing of the ‘ventral’ thin skin graft, the tissue had time to ‘mature’ and an anti-incontinence operation, like a tension-free mid-urethral sling, might be possible.

Montorsi et al.[7] used a vestibular flap urethroplasty in 17 patients. Under optical magnification, an inverted Y-shaped incision was made around the meatus and the distal part of the urethra was dissected from its perimeatal tissue from the 9 o’clock to the 3 o’clock position. The urethra was then incised ‘dorsally’ (close to the vagina) and a vestibular flap was developed superior to the urethra. Tanello et al.[8] reported the use of a pedicle flap from the labia minora for the repair of female urethral strictures. The reported success rates after 1 year of follow-up of both the cited studies are similar to ours. However, Montorsi et al. required optical magnification and the procedure of a pedicle vestibular flap cannot be used if there is vaginal fibrosis.

The present procedure of dorsal labia minora thin skin graft is easy to perform. It can be used in cases of stenosis of the mid urethra and in cases of longer urethral stenosis. The operative concept of the dorsal labia minora thin skin graft should be tested in a larger series with a long-term follow-up, and compared with other urethroplasty techniques to further evaluate benefits and pitfalls. As the bulk of the sphincter muscle fibres are beneath the pubic symphysis, transecting the membranous urethra in the 6 o’clock position causes minimal damage to the muscle fibres. Care should be taken to excise all scar tissue, and to sufficiently adapt the anterior vaginal wall to optimize blood supply to the graft.

In conclusion, the dorsal labia minora thin skin graft technique was a feasible and reliable method for female urethral reconstruction, with success in six of eight patients after a median follow-up of >2 years. Further comparative studies are necessary to validate this method.

CONFLICT OF INTEREST

None declared.

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