Key points

Introduction

The gold standard for bulbar urethroplasty has been excision and primary anastomosis (EPA), which involves excision of the strictured urethra and suturing of the healthy ends together. This method is durable and has a well-documented success rate of greater than 90%. EPA is accepted as superior to less invasive approaches to treatment, such as urethral dilation and direct visualization and internal urethrotomy. Application of this approach is generally limited to strictures that are 2 cm or less in the bulbar urethra due to potential penile shortening. Strictures greater than 2 cm are successfully treated with augmentation urethroplasty wherein the narrowed segment is not excised but widened with the use of a skin flap or, more commonly, a tissue graft.

Common modes of treatment of bulbar stricture include the following:

• 1.
  

  Urethral dilation

  
  
• 2.
  

  Direct visualization and internal urethrotomy

  
  
• 3.
  

  Urethroplasty

  
  
  
  
  • a.
    

    EPA

    
    
  • b.
    

    Augmented with tissue graft

    
    
    
    
    • i.
      

      Dorsal onlay

      
      
    • ii.
      

      Ventral onlay

      
      
    • iii.
      

      Lateral onlay

      
      
    • iv.
      

      Dorsal inlay

      
      
    • v.
      

      Dorsal inlay, ventral onlay

    
    

  
  

Introduction

The gold standard for bulbar urethroplasty has been excision and primary anastomosis (EPA), which involves excision of the strictured urethra and suturing of the healthy ends together. This method is durable and has a well-documented success rate of greater than 90%. EPA is accepted as superior to less invasive approaches to treatment, such as urethral dilation and direct visualization and internal urethrotomy. Application of this approach is generally limited to strictures that are 2 cm or less in the bulbar urethra due to potential penile shortening. Strictures greater than 2 cm are successfully treated with augmentation urethroplasty wherein the narrowed segment is not excised but widened with the use of a skin flap or, more commonly, a tissue graft.

Common modes of treatment of bulbar stricture include the following:

• 1.
  

  Urethral dilation

  
  
• 2.
  

  Direct visualization and internal urethrotomy

  
  
• 3.
  

  Urethroplasty

  
  
  
  
  • a.
    

    EPA

    
    
  • b.
    

    Augmented with tissue graft

    
    
    
    
    • i.
      

      Dorsal onlay

      
      
    • ii.
      

      Ventral onlay

      
      
    • iii.
      

      Lateral onlay

      
      
    • iv.
      

      Dorsal inlay

      
      
    • v.
      

      Dorsal inlay, ventral onlay

    
    

  
  

Grafts: what are they and what is their purpose?

A graft is tissue that is isolated for the intended purpose of relocation and repair of a damaged recipient site. Once relocated, the site of interest must provide an environment amenable to acceptance of the transfer. A graft does not have an intrinsic blood supply and relies on a robust, nutrient-rich tissue bed for imbibition of nutrients during the first 48 hours, after which inosculation of new capillaries occurs.

Types of grafts

There are 2 types of tissue grafts used in urethral reconstruction; they are differentiated by the amount of tissue transferred. A split-thickness graft is limited to the epidermis and superficial dermal plexus. This plexus contains a plethora of small blood vessels making it favorable for graft–recipient site neovascularization. Conversely, the physical properties of this tissue are not well maintained; as a result, these grafts tend to contract and are less durable. Full-thickness skin grafts include the epidermis, the superficial dermal plexus, and the deep dermis. Given that the entire dermis is included, the tissue is relatively durable, with less propensity for contraction. Unlike the superficial dermal plexus, the deep dermis is sparsely populated with blood vessels making its acceptance of neovascularization from a donor bed potentially more challenging. One should avoid using hair-bearing skin for a full-thickness skin graft because the hair follicles are in the deep dermis and will result in inflammation, stone formation, and infection in the reconstructed urethra. This issue is not a concern with split-thickness grafts. An additional type of graft commonly used in reconstructive surgery is full-thickness mucosa. Mucosal tissue differs from skin in that it has the lamina propria as a subepidermal layer. This layer contains primarily connective tissue but also small blood vessels and lymphatics. The thinner this layer is, the easier neovascularization can transpire.

History behind graft use in urethral reconstruction

There have been a myriad of different types of tissue used for the purpose of graft tissue transfer in urethral reconstructive surgery; some have been more successful than others. A favorable tissue type would include the following characteristics: easy to access and harvest, hairless, durable, viable in a wet environment, and a structure that facilitates neovascularization.

Types of tissues attempted for urethroplasty grafts are as follows:

• 1.
  

  Split-thickness skin

  
  
• 2.
  

  Full-thickness skin

  
  
• 3.
  

  Bladder epithelium

  
  
• 4.
  

  Bowel mucosa

  
  
• 5.
  

  Oral mucosa

Split-thickness grafts have limited success when used for urethral stricture repair. This limited success is likely due to their higher rates of contracture, resulting in restricture, unsatisfactory cosmesis, diverticulum formation, postvoid dribbling, and ejaculatory dysfunction. Full-thickness skin grafts from postauricular skin and the lateral abdominal wall have been described. Although no direct comparison exists and results are mixed, the full-thickness graft seems to be superior to the split-thickness graft. In comparison with mucosal grafts, some have reported higher rates of recurrence, whereas other groups have reported similar rates. The use of bladder epithelium was first described by Memmelaar and in the modern era by Ransley and colleagues. Colonic mucosal grafts have been described using both rectum and sigmoid mucosa. Because of higher rates of recurrence and sacculation as well as a relatively invasive procurement, this type of tissue is not widely used.

Oral mucosa possesses many of the ideal graft characteristics for urethral reconstruction. From a technical standpoint, it is easily harvested with minimal morbidity. Additionally, its native environment is wet, similar to the urethra. Relative to bladder, rectum, and skin, it has a thick epithelium making it relatively durable and perhaps less prone to contracture or sacculation and has a thin lamina propria making it more receptive to expeditious neovasvularization.

Oral mucosal grafts

Target sites of oral mucosal graft include the cheek (buccal), lip (labial), and the tongue (lingual). Of these, buccal mucosa has the largest accessible surface area. Although it is involved in mastication and speaking, it is not as essential as the lip or tongue. Likely as a result, when compared with buccal grafts, labial and lingual have resulted in higher graft site morbidity. In addition to favorable postoperative morbidity, the buccal graft contains the following features, making it an ideal candidate for graft tissue:

• 1.
  

  Easy to access and harvest

  
  
• 2.
  

  Hairless

  
  
• 3.
  

  Durable: full-thickness graft

  
  
• 4.
  

  Viable in a wet environment: native environment is the mouth

  
  
• 5.
  

  Structure that facilitates neovascularization: thin lamina propria

Evolution of the use of oral mucosal grafts

Although many attribute British surgeon Graham Humby as the first to successfully use buccal mucosa for urethral reconstruction, it was initially described by the Russian urologist Kirill Sapezhko in 1894. Then in 1941, Humby described a technique using buccal mucosa for hypospadias repair. The technique did not gain wide acceptance until the 1980s and 1990s. Although he did not use graft material, Monseur developed a technique in 1980 that laid the foundation for modern augmentation urethroplasty. In Monseur’s technique, he described a dorsal urethrotomy with the edges of the strictured urethra sutured to the underlying corporal bodies. Several groups began to publish their experience with buccal grafts in the early 1990s, including Burger and colleagues in pediatric reconstruction and El-Kasaby and colleagues and Duckett and colleagues in adult reconstruction.

In bulbar stricture disease, techniques for different graft locations developed in the mid 1990s. In 1996, Barbagli and colleagues modified the Monseur technique to include a dorsally placed buccal mucosal graft. During the same time, Morey and McAninch described a ventral placement of the buccal graft. Subsequently, additional graft locations have been described, including lateral onlay, dorsal inlay, and a combination of dorsal inlay and ventral onlay. Most surgical outcomes data are in the dorsal and ventral approaches to buccal placement. Most data involve retrospective single-site series making it challenging to establish definitive recommendations regarding the superiority of any one technique. The overwhelming data support similar outcomes of around 90%, regardless of graft location. Therefore, the primary driving force behind technique selection should be surgeon preference. For the remainder of this review, the authors explore the following surgical techniques as well as clinic outcomes.

Oral mucosal graft placement locations are as follows:

• 1.
  

  Ventral onlay

  
  
• 2.
  

  Dorsal onlay

  
  
• 3.
  

  Dorsal inlay

  
  
• 4.
  

  Lateral onlay

  
  
• 5.
  

  Dorsal inlay and ventral onlay

Dorsal onlay buccal mucosal graft

Surgical Technique

Barbagli and colleagues initially described this surgical approach for bulbar stricture repair. Through a perineal incision, one divides the bulbospongiosus muscle and circumferentially isolates the bulbar urethra. A dorsal urethrotomy is made through the strictured urethra. The buccal graft is then sutured to the underlying tunica albuginea of the corpora cavernosa, both along the edges of the graft and across the face of the graft. This process, known as quilting, aids in the prevention of graft elevation from an underlying hematoma or seroma, potentially preventing graft neovascularization. Quilting may also prevent graft contraction. The dorsally fixed buccal graft is then anastomosed to the urethrotomy site.

Although the graft itself is fixed to the dorsal urethra as well as corporal bodies, the surrounding muscles are completely freed, disrupting a portion of the native microvascular blood supply including circumflex and perforating arteries to the corpus spongiosum. Kulkarni and colleagues modified Barbagli’s approach by describing a unilateral urethral dissection with muscle preservation. The ischiocavernosus muscle is incised, allowing the urethra to be rotated dorsally with the bulbospongiosus muscle and the central tendon intact. The dissection is then further carried dorsally across the midline resulting in ample space for midline graft placement with only unilateral dissection. This technique is applicable to the more distal urethra as well, wherein the Buck fascia and its microvasculature can be left intact on one side ( Fig. 1 ).

Dorsal onlay approach to graft placement. Dashed line represents where the urethrotomy is made.

( From Mangera A, Patterson JM, Chapple CR. A systematic review of graft augmentation urethroplasty techniques for the treatment of anterior urethral strictures. Eur Urol 2011;59:798; with permission.)