Transurethral ventral buccal mucosal inlay grafting: a narrative review

Abstract

Background and Objective

Urethral strictures involving the meatus and fossa navicularis (FN) account for up to 18% of cases, presenting unique diagnostic and therapeutic challenges. This review explores the history and current management strategies, including minimally invasive endoscopic techniques and reconstructive options such as flap and buccal mucosal graft (BMG) urethroplasty. Open urethroplasty remains the gold standard, particularly for complex cases, but it carries undesirable risks such as dehiscence and fistula formation. We will review transurethral approaches to avoid these risks and provide a step-by-step explanation for the ventral inlay BMG FN urethroplasty.

Methods

A focused review of the literature was performed using the PubMed database with the following search terms: “transurethral”, “transmeatal”, “urethroplasty”, and “fossa navicularis”. English language articles were included, and detailed review was carried out to select the relevant articles.

Key Content and Findings

Recent advancements include transurethral approaches that minimize external incisions and associated complications, demonstrating high success rates while preserving functional and aesthetic outcomes. Key elements of the procedure include ventral scar tissue resection, harvest of a tear-shaped BMG, and use of double-armed sutures to allow for external knot tying.

Conclusions

This review highlights the importance of refining and innovating techniques to optimize patient outcomes in managing FN strictures, most recently via transurethral augmentation with BMG.

Introduction

The meatus and fossa navicularis (FN) may be involved in up to 18% of urethral strictures (1). There are unique challenges related to diagnosis and treatment, which has led to innovations in management to optimize outcomes. Approaches range from minimally invasive endoscopic procedures to flap and buccal mucosal graft (BMG) urethroplasty. Diverse etiologies of fossa strictures may stem from iatrogenic, infectious, inflammatory, and congenital anomalies (1). Transurethral surgery comprises 41% of iatrogenic strictures, with large caliber instruments leading to distal ischemia and fibrosis (2,3). Lichen sclerosis is a poorly-understood inflammatory condition that can render genital skin unusable for repair, as well as causing pan-urethral involvement (4). Endoscopic techniques have generally minimized morbidity in exchange for lower rates of durable success and higher likelihood of repeat interventions (5,6). Open incisional approaches meanwhile have had high success rates with increased risks of surgical complications such as stricture and fistula. Newer transurethral urethroplasty techniques represent exciting next steps in our treatment of this condition.

In this review, we sought to understand the history and evolution of treatment strategies for FN strictures, the current literature landscape for transurethral urethroplasty treatments, and provide detailed descriptions of our procedure. We present this article in accordance with the Narrative Review reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-24-615/rc).

Methods

This review was written with use of PubMed as the primary search database. Search terms included “transurethral”, “transmeatal”, “urethroplasty”, and “fossa navicularis”. Given the dearth of information on these novel techniques, the timeframe included all English language studies from 1975 up to and including 2024 with no restrictions on type of reference. Articles on pediatric patients were excluded (Table 1).

Table 1. The search strategy summary.

Items	Specification
Date of search	August 1–15, 2024
Databases and other sources searched	PubMed
Search terms used	“transurethral”, “transmeatal”, “urethroplasty”, and “fossa navicularis”
Timeframe	January 1, 1975–August 15, 2024
Inclusion and exclusion criteria	Included publications in English language, all study types. Excluded pediatric literature
Selection process	Selection performed by B.C.

Results

Our open-ended search yielded 194 results. We then included only English language results which reduced the number to 169 articles. These titles and abstracts were further reviewed by the one of the co-authors with a final tally of 6 articles deemed relevant. Of those articles eliminated were two on pediatric transurethral repair, as well as entries related to non-urethral anatomy and cancers of the glans and distal urethra.

History

In a survey of practice patterns in the United States by Bullock and Brandes, 93% of urologists chose dilation as the most commonly used treatment method for FN strictures (7). Dilation may be viewed as a chronic management strategy rather than a definitive cure due to a recurrence rate as high as 85% over 2 years (8). Direct vision internal urethrotomy (DVIU) is another endoscopic approach for short urethral strictures, however there are still comparatively low long-term success rates compared to more invasive techniques, and unique challenges at the distal urethra include a lack of tissue support and more difficult control over the incising instrument (9-11). Meatotomy or meatoplasty can be performed for very short FN strictures with good success rates; however there is a higher recurrence rate with lichen sclerosis, and the fish-mouth meatus can be aesthetically unsatisfactory with accompanying urine spraying (12).

Urethroplasty remains the gold standard for FN strictures, particularly complex, longer, or refractory cases (13). Surgical techniques historically have employed ventral or circumferential incisions with risk of dehiscence, fistula, and poor cosmesis (14). While there is no well-accepted number to quantify the risk of these complications, based on varying approaches single-stage repairs may carry risk from 0–16.7%, while two-stage repairs have rates of 7–59% (9,15-17). Furthermore, failure rates especially in complex cases may be as high as 54%, albeit in a small sample size (12).

Numerous proposed refinements over the years aimed to improve ease of performing the surgery, success rates, and cosmetic and functional outcomes. Early urethroplasty involved fasciocutaneous flaps using preputial or penile skin on a dartos pedicle by Cohney et al. (18). Jordan improved upon this technique with a preputial island flap disconnected completely from the skin (15). He reported long term success rate of 83% at 10 years, though lower in patients with lichen sclerosis. In order to prevent glans dehiscence, Armenakas et al. performed a glans cap under which the fasciocutaneous flap was placed before closing the cap back over the repair, with 95% long term success (11). These flaps are technically difficult and time-consuming, and still carry risks of wound complications (e.g., dehiscence and fistula) (19).

Grafts with buccal mucosa have many benefits for urethral reconstruction; they are easy to retrieve, heal quickly with minimal morbidity, and thrive naturally in wet environments such as the urinary tract (20). Numerous studies illustrated the efficacy of BMG for fossa strictures. Zumstein et al. reviewed 142 patients undergoing flap or BMG urethroplasty for meatal or fossa strictures and reported 0–100% compared to 56–100%, respectively (21). In the lichen sclerosis population, Venn and Mundy reported that BMG urethroplasty was vastly superior to pedicled skin flap, which has underscored the avoidance of genital skin for these repairs (22). Gelman et al. combined these approaches for patients with deficient urethral plates by utilizing a ventral penile island flap with dorsal BMG (16). Additional approaches with BMG in single-stage ventral onlay (23,24), dorsal inlay (21), and double buccal (25) have all shown high success rates. Hoare et al. developed a single-stage sliding T graft approach with a dorsal inlay BMG (26). This technique involved glans splitting on the ventral aspect, urethral spatulation, and incision of both the dorsal urethra as well as lateral T-shaped cuts. The BMG was secured, the urethra tubularized and glans wings closed externally. There was a 92% success rate with 30 months follow-up; two recurrences underwent meatotomy. De Laet and De Win refined a glans-sparing technique through a subcoronal transverse ventral incision, vertical urethrotomy, and dorsal inlay BMG (27). They reported 100% success rate at 12 months. Wayne et al. performed ventral onlay glanuloplasty in 10 patients with strictures 2 cm or less and without lichen sclerosis with 90% success rate over 30 months (24). This involved a ventral midline incision with a ventral onlay BMG over a 20-Fr red rubber catheter. Their technique appears to be a straightforward albeit maximally invasive approach compared to transurethral, and was performed in only short strictures without lichen sclerosis.

Staged procedures generally have a success rate of >80% (28). For long strictures greater than 4 cm, urethral plates less than 6-Fr, or severe scarring, Palminteri et al. performed multistage urethroplasty using Johanson, Asopa, or Bracka techniques (29). Multi-stage operations may be a good alternative for long or complex distal urethral strictures depending on surgeon experience and preference.

Transurethral approaches

The next innovation in technique was transurethral attempts to avoid external incisions and their associated risks. Onol et al. used a circular BMG with 84% success rate at 38 months (30). There were 19 patients with a median age of 41.8 years and distal stricture less than or equal to 2 cm, 16 of whom had lichen sclerosis. They began by excising the scar circumferentially to healthy tissue, then fashioning a 4 cm × 1.5–2.5 cm rectangular graft around a 24-Fr sound. If necessary, a subcoronal transverse incision was made. The proximal and distal edges were sutured in placed and a foley catheter was placed for 10–14 days. They reported improvement in Qmax from 7.8±5.4 to 21.8±9.2 mL/s (P=0.001). Three patients were unsuccessful, with graft failure in one and proximal recurrence in two. Nine patients out of 19 (47%) required a counter-incision.

Nikolavsky et al. first introduced their transurethral BMG ventral inlay technique in three patients with mean age of 42 years old and recurrent FN strictures with an average length of 2.1 cm (31). All three patients had undergone a minimum of two prior interventions, two had lichen sclerosis, and one had coronal hypospadias status post pediatric repair and subsequent revision. The technique in detail is described below. Importantly, they avoided additional external incisions and focused their scar excision and graft placement on the ventral aspect only. Uroflowmetry results improved from 4.3 [0–8] mL/s pre-operatively to 19 [16–26] mL/s post-operatively. Over 18-month follow-up, there was no recurrence, fistula, chordee, wound complications, or sexual dysfunction, and all three patients rated the Global Response Assessment (GRA) for surgical satisfaction as the highest possible grade of +3. Their results were then replicated in an international multi-institutional cohort of 68 patients with at least 1 year follow-up had 95% success at 17 months (32). Median age was 60 years old and stricture length 2 cm. This was a complex population, with high rates of diabetes (25%), smoking (32%), lichen sclerosis (39%), hypospadias (9%), and prior dilations (75%), DVIU (11%), and meatoplasty/urethroplasty (18%). Operative time was 72 min [interquartile range (IQR), 50–120 min] and 92% returned home on post-operative day 0 or 1. There were no Clavien-Dindo grade 3 or greater complications. They again reported significant improvements in Qmax (P<0.0001), post void residual (PVR) (P<0.0001), International Prostate Symptom Score (IPSS) (P<0.0001), and quality of life (P<0.0001), and moderate or marked improvement on GRA in 92%. There was no fistula, dehiscence, graft failure, sexual dysfunction, or chordee. Intermediate-term outcomes of 36 months have solidified the durability of this type of repair (33). The procedure was also successful in patients with hypospadias, and had mixed results on urine spraying (six with resolution of pre-existing spray, ten with no change, and seven with de novo spraying). There were two patients who recurred proximally requiring repeat dorsal onlay BMG.

Ehlers and Figler performed a transurethral double-face buccal urethroplasty in 10 patients and inlays only in two, with 90% success over 18 months follow-up (34). They did this by removing scar tissue and placing sutures prior to graft harvest. Their BMG was split into two separate pieces with the dorsal graft secured first followed by the ventral. The final step was placement of the distal meatal sutures. There was one failure who required dilation and clean intermittent catheterization.

Farrell et al. investigated dorsal inlay BMG in 16 patients with 28 month follow-up (35). They made a dorsal urethrotomy and excised a triangular wedge of scar tissue. The BMG was inserted and the urethral lumen calibrated to 20 Fr. There was high satisfaction, and 93.8% anastomotic and 100% functional success. There was notably improvement in those patients suffering from urine spraying without development of de novo split stream.

As demonstrated above, transurethral techniques have uniformly high success rates with low morbidity, even in patients with complicating disease factors such as lichen sclerosis, hypospadias, and prior surgery. Once the relatively small learning curve has been surmounted, these techniques can be performed quickly as there are no running sutures or multiple layers of external incision to close; furthermore, having a second team available to assist harvesting the graft further expedites the process. For short FN strictures, no specially designed instruments are required to visualize, incise, or place sutures. In our technique, a catheter is left in place for only 1 week, easing the burden and discomfort of post-operative care on the patient. The advantages of a dorsal graft include a robust graft bed and being able to perform a two-stage approach or more proximal repair if the stricture is more extensive. There is lower risk of urine spraying by leaving the ventral side alone, which can be a bothersome symptom (36). We have found that the ventral transurethral approach can be performed even in strictures that extend more proximally into the penile urethra with instruments that aid in visualization and suturing (such as nasal speculum and long, thin thoracoscopic needle drivers), and find the ease of external suture placement and knot tying makes this technique preferable.

The future of transurethral FN repairs involves multiple avenues. One includes the development of new instruments to facilitate visualization, incision, and graft placement. Notably, Warner is pioneering endoscopic urethroplasty using specialized scopes and suturing devices (37). Additional research is ongoing into the chemical environments and mechanical and biological properties of urethral strictures, as well as graft/tissue replacements (38,39). Other priorities include understanding how to improve healing and prevent recurrence of fibrosis.

Transurethral ventral inlay proposed by Nikolavsky

Our technique (Figure 1) aims to address the challenges and risks associated with prior approaches, namely the risks of wound dehiscence, urethrocutaneous fistula, poor cosmesis, and difficulty suturing transurethrally.

Figure 1.

Step-by-step technique of the transurethral fossa navicularis BMG repair. (A) Ventral wedge of scar tissue is sharply excised. (B) Double-armed 6-0 PDS sutures are used to parachute the graft into position at the proximal apex. (C) Distal sutures are tied to fix the graft at the meatus. (D) Additional double-armed sutures are placed to quilt the graft. Reprinted with permission from Daneshvar et al. (32). BMG, buccal mucosal graft; PDS, polydioxanone suture.

Primarily we utilize this technique for FN, meatal stenosis, and distal penile urethral strictures. The ability to perform longer strictures is limited by the instruments available to feasibly visualize the proximal extent and pass sutures here.

Once the patient is prepped and draped in supine position, we begin with antegrade cystoscopy through a suprapubic tube (SPT) tract if applicable, and mark the proximal limit of the stricture externally. We pass a straight sensor wire through the stricture, and place a new 16-Fr catheter antegrade to drain the bladder. Alternatively, if there is no SPT in place, then we pass the wire retrograde, then advance a Fogarty catheter past the stricture, inflate the balloon, and retract it until it meets resistance.

We inject 1 cc of methylene blue into the urethra, which stains healthy urethral epithelium. The surgical site is exposed using 3-0 polydioxanone suture (PDS) at 10, 12, and 2 o’clock, and secured with snaps over a Lonestar ring retractor folded at a 90-degree angle perpendicular to the patient’s abdomen. At this point, we harvest a tear-shaped BMG in the standard fashion. It is important that the graft be 2.5–3 cm wide at its largest end, and 1.5 cm longer than the stricture. We find it easier to excise the wider part of the graft more superficially with the narrow point deeper in the mouth.

We begin by making lateral incisions with a 15-blade or ophthalmic blade at 3 and 9 o’clock from the proximal edge of the stricture to the meatus. Once this is done, a nasal speculum can be inserted which helps both with exposure and compression on the incisions. We use a thin metal suction tip to aid in visualization. We then perform sharp dissection to remove the ventral blue-stained epithelium and create our graft bed. This is continued until the blue tissue is excised and we can pass a 28-Fr bougie without resistance.

We then use double-armed 6-0 PDS sutures to secure the graft at the narrow tip proximally, first passing both needles from “outside in” through graft, then transurethrally through the proximal apex “inside out” through penile skin. These latter throws (and all subsequent transurethral suture throws) are made with the needle grasped in parallel to the needle driver tips. The graft is parachuted into place, the needles are cut off, and the ends tied. The distal wide edge of graft is trimmed at the meatus and secured with interrupted 5-0 polyglactin sutures for patient comfort. We then place a series of quilting sutures using the double-armed 6-0 PDS sutures in the same manner as described above, using the nasal speculum for exposure. The most distal quilting sutures may be thrown with a more traditional forehand using a single-armed suture from outside in and then back out. Efforts are made for both arms of the transurethral sutures to exit at the same location to prevent bunching of the penile skin.

With the graft secured in place, a well-lubricated 16-Fr silicone catheter is placed and secured on the abdomen to prevent disruption of the ventral graft. A dorsal penile block is performed for analgesia. No special compressive dressing is necessary aside from fluffs and mesh underwear.

Conclusions

The management of FN strictures presents unique challenges, but recent innovations in surgical techniques show promising outcomes. The introduction of transurethral surgery minimizes the complications associated with external incisions while maintaining efficacy, and represents an exciting development toward less invasive repairs.

Supplementary

The article’s supplementary files as

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.