Urethral Strictures in Males

Updated: Dec 30, 2018
  • Author: Joshua A Broghammer, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Overview

Practice Essentials

Urethral strictures can result from inflammatory, ischemic, or traumatic processes. These processes lead to scar tissue formation; scar tissue contracts and reduces the caliber of the urethral lumen, causing resistance to the antegrade flow of urine.

The term urethral stricture generally refers to the anterior urethra and is secondary to scarring in the spongy erectile tissue of the corpus spongiosum. A posterior urethral stricture is due to a fibrotic process that narrows the bladder neck and usually results from a distraction injury secondary to trauma or surgery, such as radical prostatectomy. [1]  The focus of this article is anterior urethral stricture disease.

Urethral strictures arise from various causes and can result in a range of manifestations, from an asymptomatic presentation to severe discomfort secondary to urinary retention. Retrograde urethrogram (RUG) is the main diagnostic method to find anterior urethra stricture and help find the length of the stricture.

Establishing effective drainage of the urinary bladder can be challenging, and a thorough understanding of urethral anatomy and urologic technology is essential. See the images below.

Urethral strictures. Cross-sectional diagram of th Urethral strictures. Cross-sectional diagram of the penis.
Urethral strictures. Schematic of penile anatomy. Urethral strictures. Schematic of penile anatomy.

Many techniques are available for the treatment of urethral stricture disease. Based on the literature, no technique can be applied successfully to every situation. Each technique has advantages and disadvantages. [2, 3, 4]  

The role of tissue engineering and stem cells in urethral reconstruction

Tissue engineering incorporates the disciplines of cell transplantation, materials science, and engineering with the objective of creating functional replacement tissue. El Kassaby et al published a randomized comparative study of buccal mucosal and acellular bladder matrix grafts. An off-the-shelf matrix derived from the bladder was used. This biomaterial was obtained from donors and prepared via a multistep process, resulting in the removal of all cellular components. The tissue matrix that remains consists of collagen, elastin, growth factors, and macromolecules. Predicated on biocompatibility and the ability to recruit urethral tissue growth in several experimental and clinical studies, this matrix was used.

With a mean follow-up period of 25 months in patients with a healthy urethral bed, the success rates for the acellular bladder matrix were similar to those using buccal mucosa. In patients who had undergone two or more prior urethral surgeries with significant spongiofibrosis, the success rate significantly deteriorated for the acellular matrix relative to buccal mucosa. This study demonstrates promise for the use of acellular matrices as a viable option for urethral repair in patients with a healthy urethral bed, no fibrosis of the corpora spongiosis, and good urethral mucosa. [5]

 

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Relevant Anatomy

The urethra is divided into anterior and posterior segments. The anterior urethra (from distal to proximal) includes the meatus, fossa navicularis, penile or pendulous urethra, and bulbar urethra. The posterior urethra (from distal to proximal) includes the membranous urethra and the prostatic urethra.

The urethra lies within the corpus spongiosum, beginning at the level of the bulbous urethra and extending distally through the length of the penile urethra. The bulbar urethra begins at the root of the penis and ends at the urogenital diaphragm. The penile urethra has a more central position within the corpus spongiosum in contrast to the bulbous urethra, which is more dorsally positioned.

The membranous urethra involves the segment extending from the urogenital diaphragm to the verumontanum.

The prostatic urethra extends proximally from the verumontanum to the bladder neck. The soft-tissue layers of the penis, from external to internal, include the skin, superficial (dartos) fascia, deep (Buck) fascia, and the tunica albuginea surrounding the corpora cavernosa and corpus spongiosum.

The superficial vascular supply to the penis comes from the external pudendal vessels, which arise from the femoral vessels. The external pudendal vessels give rise to the superficial dorsal penile vessels that run dorsolaterally and ventrolaterally along the penile shaft, providing a rich vascular supply to the dartos fascia and skin. The deep penile structures receive their arterial supply from the common penile artery, which arises from the internal pudendal artery. The common penile artery gives off several branches, including the bulbourethral, cavernosal, and deep dorsal penile arteries. The corpus spongiosum receives a dual blood supply via anastomoses between dorsal and urethral artery branches in the glans.

The scrotum receives its vascular supply via branches from both the external and internal pudendal arteries. See the images below.

Urethral strictures. Cross-sectional diagram of th Urethral strictures. Cross-sectional diagram of the penis.
Urethral strictures. Schematic of penile anatomy. Urethral strictures. Schematic of penile anatomy.
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Pathophysiology

Anterior urethral injury most often results from a blunt force blow to the perineum, producing a crushing effect on the tissues of the urethra. The initial injuries are often ignored by the patient, and urethral injury manifests years later as a stricture. The stricture results from scarring induced by ischemia at the site of the injury. 

A congenital stricture results from inadequate fusion of the anterior and posterior urethra, is short in length, and is not associated with an inflammatory process. This is an extremely rare cause.

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Etiology

The most common causes of urethral stricture today are traumatic or iatrogenic. Inflammatory or infectious, malignant, and congenital etiologies are less common. Approximately 30% of urethral strictures are idiopathic.

Iatrogenic urethral trauma usually results from improper or prolonged catheterization and accounts for 32% of strictures. [6]  The size and type of catheter used have an important impact on urethral stricture formation. Silicone catheters and small-calibre Foley catheters are associated with less urethral morbidity. 

Urethral stricture after radiation therapy for prostate cancer is a late complication usually observed 1–3 years after radiation. The overall reported incidence of urethral stricture after radiation therapy for prostate cancer varies between 0%–18%. Urethral stricture occurs in about 2% of patients undergoing external beam (EBRT), 4% for brachytherapy (BT) and 11% of EBRT-BT combination therapy. Several risk factors for the development of a urethral stricture have been identified. Previous transurethral resection of the prostate (TURP) increases the stricture rates up to 15% compared to 6% without prior resection. History of arterial hypertension in combination with diabetes mellitus is also a predictive factor, as this may lead to reduced blood supply due to changes in microcirculation. [7]  

Lichen sclerosus is a chronic, inflammatory skin condition of the genitalia of unknown origin that accounts for nearly 10% of urethral strictures. [8]

Infectious urethral strictures are secondary typically to gonococcal urethritis, which remains common in certain high-risk populations.

 

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Epidemiology

The narrowing of the urethra is estimated between 200 and 1200 cases per 100 thousand people, and it will be dramatically increased within people over 55 years. In estimation, the prevalence of urethral stricture in industrial countries is around 0.9%. [9]

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Prognosis

The outcomes of urethral reconstruction for lichen sclerosus (LS) urethral strictures are poor, with reported stricture recurrence rates ranging from 20% to 50%. LS strictures are generally longer and have a penile urethral location, both of which independently increase the risk of recurrence. In contrast, non-LS strictures is usually shorter and located in the bulbar urethra. [8]

For patients with RT-induced strictures, radiation damage may result in vasculare atrophy, poorly oxygenated tissue and/or collagen deposition with eventual tissue scarring. The decreased availability of tissue healing and the close relation to the sphincter complicates any surgical approach. Dilatation and/or direct vision internal urethrotomy (DVIU) results are poor with success rates ranging from 0%-20%. [7]

In the largest study examining the outcome of men treated for RT-induced strictures, Hofer et al. examined 72 patients (42% received BT, 42% received EBRT and 14% combination EBRT-BT) with a mean stricture length of 2.3 cm. The majority of the patients (n=66) were treated with stricture excision and primary anastomosis (EPA). Intervention was successful in 70% of the patients. The median time to recurrence was 10,2 months. New onset incontinence was reported by 12 men (18.5%) but the rate of erectile dysfunction remained stable (preoperative, 45.6%; postoperative, 50.9%. [10]  

Urethral dilation and internal urethrotomy

A prospective randomized comparison of internal urethrotomy and urethral dilation for male urethral strictures found no significant difference in efficacy between the two procedures when used as initial treatment. [11]  Recurrence rates increased as the length of the stricture increased. Recurrence rates at 12 months were 40%, 50%, and 80% for stricture lengths of less than 2 cm, 2-4 cm, and greater than 4 cm, respectively. The recurrence rate for strictures 2-4 cm long increased to 75% at 48 months of follow-up.

Permanent urethral stents

Five-year follow-up data demonstrated a long-term success rate of 84% and high level of patient satisfaction. [12]  Failures typically occurred in patients with extensive stricture disease. The North American Study Group 11-year data demonstrated an overall success rate of less than 30%. [13]  A European group reported 2 out of 15 satisfied patients 10 years postimplantation. [14]  An Italian multicenter study following 94 cases reported on the short- and long-term complications. [15]  Short-term complications (7-28 d following the procedure) included perineal discomfort (86%) and dribbling (14%). Long-term complications included painful erections (44%), mucous hyperplasia (44%), recurring stricture (29%), and incontinence (14%). Additionally, some unique complications are associated with permanently implantable stents. The stents are designed for placement within the bulbous urethra. If they are placed distally, there is a risk of pain upon sitting and intercourse.

Excision with primary anastomosis

This form of repair for anterior urethral strictures is considered to be the criterion standard. Historically, this technique has been reserved for strictures shorter than 2 cm. Better understanding of the anatomy has led to successful application of this repair to longer strictures. Jordan and Schlossberg (2007) reported 3 recurrences among 220 patients undergoing primary repair, with a mean follow-up period of 44 months. [16]  Mundy (2006) performed an analysis of a large series of urethral reconstructions and described a durable rate after primary repair that does not deteriorate with time. [17]

Free graft repair

These procedures have an overall success rate of 84.3%. Mundy's analysis demonstrated a 95% success rate with graft reconstructions when the follow-up was limited to 1 year. Longer follow-up showed deterioration over time. [17]

Pedicled skin flaps

The overall success rate is 85.5%. Skin island onlay flap with preservation of the urethral plate provides better success rates than the tubularized flap. Tubularized island flaps have lower success rates than skin island onlay flaps secondary to stricture formation at the site of anastomosis with the native urethra. [18]

A meta-analysis showed equivalent results when comparing graft versus flap reconstruction. [19]  Many authors believe grafts are better suited for proximal reconstruction than flaps for distal reconstruction when all other variables are equivalent. [20]

Postoperative erectile dysfunction

Overall, the rates of erectile dysfunction after urethral reconstruction are low. Reported rates are as low as 2%. [16]  Patients with severe straddle injuries were particularly at risk. A series of 200 patients who underwent anterior urethroplasties demonstrated that the rate of erectile dysfunction was comparable to that after circumcision. Patients who had longer segments of their urethra reconstructed were at higher risk. In this analysis, erectile dysfunction did improve over time. [21]

A study to evaluate whether the type of one-stage urethroplasty has any influence on recovery from erectile dysfunction found that although the procedure has a probability of causing erectile dysfunction in as many as 20% of patients, the type of urethroplasty has no bearing on recovery, which generally occurs within 6 months. [22]

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