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Surgical Illustration – Hypospadias Repair

Date: June 14, 2017 Category:

 

Proximal Hypospadias Repair – Surgical Illustration

Created on behalf of Lurie Children’s Hospital for the Journal of Pediatric Urology.  In press 2017

  • Concepts drawn from surgical photos & surgeon sketches
  • Linework finished in Adobe Photoshop
  • Article below

In the authors’ experience, single stage proximal hypospadias repairs are best reserved for patients with a healthy urethral plate and a degree of curvature chordee that is amenable to a dorsal plication technique.  This tends to be a smaller percentage of our patients with proximal hypospadias. Although it has been suggested that most urethral plates in cases of proximal hypospadias are amenable to a TIP repair, we have found that in cases where the plate is narrow or unhealthy, long term results are suboptimal with an increased incidence of stricture formation, especially in the subcoronal area where the plate tends to be less pliable.  Thus, in cases where either the urethal plate or degree of chordee curvature are borderline, we tend to prefer a 2 stage repair.

At the beginning of each case we first assess the quality of the urethral plate.  If it is felt that the plate may be appropriate for use for a TIP repair, then we will begin by making a modified circumscribing incision with creation of mucosal collar flaps (Firlit flaps) and a ventral incision around the urethral plate.  In select cases where the skin lateral to the urethral plate is healthy and non hear bearing, we may choose to include this tissue for use along with the urethral plate. **Figure 1A: Mucosal collar flaps with intact urethral plate

The chordee tissue is released and an artificial erections is performed.  If the curvature is less than 300, then dorsal plication is performed along with a TIP repair.  If the curvature is greater than 300, then division of the urethral plate is undertaken.  The plate can either be divided distally or proximally.  As previously described (Cheng et al), we will divide the plate proximally and tubularize the distal plate out to the tip of the glans if the urethral plate within the glans is healthy.  If the distal urethral plate is not amenable to be used in this fashion, we will then divide the plate distally with tubularization of the proximal portion of the urethal plate. Curvature is reassessed after urethral plate division and excision of the dysgenetic tissue overlying the corporal bodies.  We have found in most cases that division of the plate usually does not have a significant impact on the overall degree of curvature.  However, in some cases, division of the plate will improved the degree of curvature such that dorsal plication can now be performed. In the remaining cases, corporal body grafting is our preference for correcting the residual curvature.  We have not routinely utilized corporal body incisions (fairy cuts)  (Snodgrass reference?).  We prefer to use single layer small intestinal submucosa (SIS) for grafting.  When making the corporal body incision to release the chordee, it is important to carry the incision as lateral as possible to adequately correct the ventral tethering form the corporal body disproportion.  This requires making an incision that comes close to the edge of the dorsal neurovascular bundles on each side.  It is also important to elevate the wall of the corporal body from the underlying erectile tissue to create an adequate defect for grafting.  FIGURE 1B: Chordee correction

Once corporal body grafting is complete, transfer of skin flaps is needed for use for creation of a neourethra at the time of the second stage.  Traditionally, this has been done with Byar’s flaps that are brought together in the midline.  As has been noted in several recent studies, we have found the long-term results with this technique to be less than satisfactory for several reasons.  Due to the nature of the skin that makes up the Byar’s flaps, the resultant neourethra after the second stage tends to be longer than normal, at times hypermobile, and with irregularities within the lumen that can make catheterization difficult.  The neourethra is also prone to diverticulum formation.

Currently, we have utilized a combined flap and graft that is derived from a transverse preputial island flap similar to that used for onlay repairs.  The majority of the flap is harvested with its associated blood supply and then used to cover the urethral defect over the ventral shaft and area of corporal body grafting. ***FIGURE 1C

The most distal aspect of the flap is defatted and then used as an inlay graft within the glans after the urethral plate is incised (similar to that done for a first stage buccal mucosa urethroplasty). *** FIGURE 1D

The vascularized flap and inlay graft are mattressed to the tunica albuginea to create a new urethral plate that is flat and well buttressed to the underlying corporal bodies.  The distal graft is also fenestrated to prevent subcutaneous hematoma and seroma formation.  FIGURE 1E

The remaining skin is then brought along side the flap.  It is important to create a smooth transition between this skin and newly created urethral plate since some cases require use of some of this adjacent skin at the time of the second stage.  We have found that the manner in which the flap and adjacent skin are reconstructed are critical to the success of the creation of the neourethra at the time of the second stage.  The second stage involves tubularization of the preputial flap and inlay graft.  This is usually done in 2 layers with interrupted subcuticular stitched for the first layer. Vascualrized coverage is either done with dartos flap or tunica vaginalis  flap. Since the original vascularized flap that was utilized at the time of the first stage uses most of the well vascularized dartos tissue, we find that most cases of coverage at the time of the second stage are best accomplished with use of tunica vaginalis flap.

Post-operative diversion is done for 2 weeks with a urethral drip catheter.  As will be discussed in more detail in the following section, future evidence based studies with long term follow-up will better determine whether our current surgical approach will result in functional results that are better than what we have done historically.