Surgery for Urethral Trauma Including Urethral Disruption



Surgery for Urethral Trauma Including Urethral Disruption


TIMOTHY J. TAUSCH

JAY SIMHAN

ALLEN F. MOREY



Early recognition and diagnosis of urethral injuries are crucial to the successful management and prevention of long-term complications. Management of traumatic urethral injuries depends on the location of urethral stenosis. The urethra is divided into anterior (pendulous and bulbar urethra) and posterior (membranous and prostatic urethra) segments, with specific mechanisms of injury for either segment that will ultimately influence therapy and outcomes. Immediate management of anterior and posterior urethral trauma predominantly involves temporizing solutions to divert urine away from the urethral injury, although immediate surgical management of acute anterior urethral trauma may often be appropriate. Many patients with posterior injuries ultimately require formal surgical repair several months following the initial injury.


ANTERIOR URETHRAL INJURIES

The anterior urethra extends distally from the membranous urethra to the urethral meatus (Fig. 40.1). Contrary to the posterior urethra, the anterior urethra is encompassed by the corpus spongiosum, the deep (Buck) fascia, and the superficial (dartos) fascia along its entire length. The penoscrotal junction divides the shorter, proximal bulbar urethra from the longer, distal pendulous urethra. The bulbospongiosus muscle ventrally covers the bulbar urethra and terminates at the penoscrotal junction, prior to the origination of the distal pendulous urethra. The pendulous urethra closely approximates the corpora cavernosa during most of its length, with the lumen of the distal pendulous urethra dilating distally to form the fossa navicularis.






FIGURE 40.1 Anatomy of the anterior and posterior urethra.

Although susceptible to penetrating trauma (e.g., stab or gunshot wounds), injuries to the anterior urethra most commonly involve blunt compression (“straddle”) injuries, penile fracture with concomitant urethral disruption, iatrogenic trauma (e.g., after Foley catheterization or endoscopic urethral surgery), and constriction rings. Compression of the bulbar urethra against the pubic bone, or a “straddle injury,” is the most commonly encountered anterior urethral injury and occurs after a direct force to the perineum compresses the bulbar urethra against the pubic bone. Alternatively, penile constriction rings can damage the anterior urethra secondary to tissue ischemia, whereas Foley catheterization or endoscopic urethral surgery can damage the bulbar urethra, resulting in contusion or partial urethral disruption. The true extent of iatrogenic injuries, along with trauma from constriction rings,
may not become evident until many years after the original event (1). Although rarely associated with pelvic fractures, anterior urethral injuries may be encountered in approximately 15% of penile fractures (2).



Indications for Surgery

Primary surgical repair of acute anterior urethral injuries is recommended in the context of penetrating injury. We also recommend an attempt at anterior urethral repair in the setting of penile fracture. Because these repairs are delicate and potentially time-consuming, any attempt at immediate repair is predicated on the stability of the patient. Injuries to the posterior urethra should be managed in a delayed fashion, without attempt at a formal urethroplasty in the acute setting. Posterior urethral injuries are discussed later in this chapter.


Alternative Therapy

Alternative options to surgical repair involve the temporary diversion of urine through the placement of a urethral or suprapubic catheter. Contusions to the anterior urethra should be managed with a urethral catheter for approximately 2 weeks followed by a voiding cystourethrogram to confirm urethral patency. The patient should be counseled on the possibility of delayed development of a urethral stricture at the site of contusion.

Partial urethral disruptions diagnosed by retrograde urethrogram may be managed via various algorithms. We prefer urinary diversion with formal repair after a minimum of 2 months to allow resolution of inflammation and maturation of scar tissue. Although some experts support one attempt at Foley catheter placement, the possibility of causing a complete urethral disruption during this attempt should be considered.
If urethral placement is unsuccessful, percutaneous suprapubic tube placement should be performed. The preservation of urethral mucosa with partial disruptions may be adequate for re-epithelialization and eventual luminal recanalization; however, we would recommend periodic evaluation with uroflow studies and counseling patients regarding the possibility of future stricture development.


Surgical Technique

Open surgical repair is primarily reserved for stable patients after open or penetrating injury to the anterior urethra. The patient is placed in either the supine position or lithotomy position and draped widely to allow exploration of potential concomitant injuries to the penis, testes, perineum, and rectum. Clean wounds need only minimal debridement followed by urethral closure with interrupted or running 5-0 polyglyconate monofilament (polydioxanone) sutures over a 16Fr catheter. Contaminated wounds require thorough irrigation and debridement of devitalized tissues to ensure reapproximation of healthy tissue.

With open or penetrating bulbar urethra injuries, the patient is placed in the lithotomy position with adjustable stirrups, and a vertical perineal incision is performed along the raphe. As expected, only stable patients without injury precluding the lithotomy position should be offered acute surgical intervention. The urethra is exposed after division of Colles fascia and the bulbospongiosus muscle. A perineal retractor (e.g., perineal Bookwalter or Lone Star retractor, Cooper Surgical, Trumbull, Connecticut) is used to assist with perineal dissection. Surgeons should avoid acute repair of long bulbar urethral defects (>2 to 3 cm) because more complex intervention with grafts or flaps will be required. The most important factor promoting a successful outcome is the creation of a tension-free anastomosis; therefore, generous mobilization of the urethra is an important step to ensure adequate urethral length. Once adequate length is achieved, the urethral ends are spatulated (Fig. 40.3). The anastomosis is performed with interrupted 5-0 polyglyconate monofilament suture to create a tension-free, watertight closure. The dorsal surface is closed in one layer with 5-0 interrupted polyglyconate monofilament suture incorporating the urethral mucosa and spongiosal adventitia. Since the ventral bulbar urethra is vascularized by the spongy urethra, we advocate ventral spongiosum closure in two layers: the first, inner layer, closed with interrupted 5-0 polyglyconate monofilament suture and the second, outer layer, with a running 5-0 polyglyconate monofilament suture (Fig. 40.4). No further attempt is made to control bleeding from the spongy urethra during closure, as we believe that the added vascularity from the spongy urethra provides enhanced healing of the anastomosis. We also recommend that a firststage marsupialization of healthy proximal urethra be considered if tension-free closure cannot be achieved or if there is significant wound inflammation or contamination.






FIGURE 40.3 Repair of bulbar urethral injuries. The urethra is mobilized and spatulated in preparation for a tension-free end-to-end anastomosis.






FIGURE 40.4 Repair of bulbar urethral injuries. Anastomosis is carried out with a single-layer dorsal closure and a two-layer ventral closure using interrupted 5-0 or 6-0 Maxon sutures.

For most penile urethral injuries, we prefer a longitudinal incision directly over the area of injury. Contrary to bulbar urethral injury, anastomotic repair should not be considered for defects >15 mm, as the risk of penile chordee is higher with penile anastomotic repairs. Instead, we prefer to use buccal mucosa in either an inlay, onlay, or combined approach. We routinely use 16Fr silicone Foley catheters at the time of urethral repair. Suppressive antibiotics are given while the catheter is in place to maintain urine sterility, with a voiding cystourethrogram performed after 2 to 3 weeks. If extravasation is noted, we gently replace the catheter for an additional period of time with repeat imaging at the time of urethral catheter removal.




POSTERIOR URETHRAL INJURIES


Posterior Urethral Anatomy

The urethra is divided into anterior and posterior anatomic segments by the urogenital perineal membrane. The posterior urethra consists of the membranous and prostatic urethra and is much shorter than the anterior urethra (Fig. 40.1). Extending from the bladder neck to the apex of the prostate, the prostatic urethra is secured to the pubic bone by the paired puboprostatic ligaments. During cystoscopy, the verumontanum marks the most distal aspect of the prostatic urethra. The bladder neck sphincter is an extension of smooth muscle fibers of the trigone and prostatic urethra cephalad to the verumontanum. The distal sphincter is approximately 2.5 cm long and consists of smooth muscle fibers caudad to the verumontanum, including the rhabdosphincter (slow-twitch skeletal muscle fibers) (4). The distal sphincter is only 3 to 4 mm thick and forms the entire thickness of the membranous urethra (5). In the absence of a functional distal urethral sphincter, the proximal urethral sphincter can maintain urinary continence in select patients; however, the bladder must be compliant and free from periodic elevations of detrusor pressure (e.g., detrusor overactivity).

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Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Surgery for Urethral Trauma Including Urethral Disruption

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