Introduction
The male urethra can be divided anatomically into anterior and posterior segments. The anterior portion is further divided into the bulbous, pendulous, and fossa navicularis or meatal urethral segments (also referred to as the distal urethra; Figure 1). The term 'urethral stricture' specifically refers to scarring of the spongy tissues of the corpus spongiosum (spongiofibrosis of the anterior urethra). As this scar contracts, the lumen of the urethra narrows and effects on voiding are seen.
Figure 1 | Sagittal section of the pelvis.
The urethra is subdivided into the following sections: (1) fossa navicularis; (2) pendulous or penile urethra; (3) bulbous urethra; (4) membranous urethra; (5) prostatic urethra; (6) bladder neck. By common usage, the fossa navicularis, pendulous urethra, and bulbous urethra comprise the anterior urethra, and the membranous urethra, prostatic urethra, and bladder neck comprise the posterior urethra.
The overall incidence of stricture disease might be as high as 0.6% in certain populations. In some populations, inflammatory disease can cause anterior stricture disease; in developed countries, prompt antibiotic therapy of urethritis is thought to diminish the incidence of these strictures. In virtually all populations, trauma is likely to be the most common cause of anterior strictures.1 Strictures of the anterior urethra can be seen in patients of all ages, but their etiology differs in prevalence between age groups. In children, stricture can certainly be caused by trauma, but congenital strictures and those associated with idiopathic urethrorrhagia present more frequently in childhood than in adulthood. Stricture disease is responsible for as many as 5,000 hospitalizations and 1.5 million outpatient visits per year in the USA, at an annual cost of US$200 million.1
Management of urethral stricture disease within each urethral segment is determined by the individual etiologic characteristics, cosmesis and availability of local tissues for use in reconstruction. Treatment options are dilatation, urethrostomy and open reconstruction. In the proximal anterior urethra, implantable stents have been proposed as a management option, but stents have no place in the distal anterior urethra. We begin this Review by describing some of the factors that lead to urethral stricture disease, paying special attention to the most distal urethral segment. We will then discuss the diagnosis and management options for these patients, with a focus on the different techniques of open surgery.
Etiology of urethral strictures
In general, strictures of the anterior urethra can result from any process that causes injury to the urethral epithelium or corpus spongiosum and leads to scar formation. Such causes can include infection, trauma, iatrogenic injury, inflammatory disorders and congenital issues. Anterior urethral strictures might, however, occur idiopathically.
Strictures of the distal anterior urethra are typically short and occur with less frequency than those in other urethral segments. According to one report, distal strictures comprise only 18% of anterior urethral strictures, although 11% of patients assessed had stricture disease in multiple urethral segments.2 The etiology of distal urethral strictures is evenly split between idiopathic, iatrogenic and inflammatory causes in several studies.3
Trauma and iatrogenic injury
Today, trauma—specifically, straddle trauma—is the most common cause of anterior urethral strictures.4 Iatrogenic injury as a result of catheterization or transurethral endoscopy can cause spongiofibrosis, especially in the most distal segment of the anterior urethra. With the development of flexible endoscopes that have a smaller caliber than those formerly used, as well as the use of diligent care for patients with indwelling catheters, fewer iatrogenic injuries occur today than previously. Despite this decrease, stricture rates after transurethral resection procedures are reportedly as high as 6.3%, and 41% of these cases involve the fossa navicularis and meatus (distal region).5
Infectious and inflammatory causes
Historically, infectious urethritis caused by Neisseria gonorrhea was a common cause of anterior urethral stricture disease; however, with the advent of prompt diagnostic testing and increased efficacy of antibiotic treatments, this infection is now less common.
Perhaps the best-recognized inflammatory etiology of distal urethral strictures is lichen sclerosus. In male patients, this chronic dermatosis is also termed balanitis xerotica obliterans and primarily involves the prepuce and glans penis; however, the condition can progress to involve other genital tissues. The exact etiology is unknown, although infection, autoimmune reaction and genetic predilection have all been proposed as possible causes.6 Balanitis xerotica obliterans presents as whitish, dry macular lesions; occasionally, visible meatal stenosis is present. Strictures related to balanitis xerotica obliterans are the exception to the rule that strictures of the distal urethra are typically short. In many instances, strictures associated with balanitis xerotica obliterans can at initial presentation occupy much of the pendulous urethra, although the bulbous urethra is often spared.
Diagnosis and evaluation
When urethral stricture is suspected as an etiology of voiding dysfunction, the location, length, density and depth of the spongiofibrosis are important to ascertain. A combined clinical, radiographic and endoscopic evaluation allows collection of these data.
Clinical assessment
Common presentations of urethral strictures include acute urinary retention, straining to void, splaying of the urinary stream and infections of the urinary tract, including recurrent epididymitis and prostatitis. Those patients who present late in the course of the disease show thickening of the bladder wall, diverticulum formation, and acute or chronic renal failure. Many patients might recall an insidious onset of voiding complaints before the frank presentation.
Inspection of the urethral meatus is very important. A scarred meatus, a scarred and retrusive meatus, or a scar of the meatus along with changes in the texture and color of the glans or preputial or penile skin can be indicative of the presence of balanitis xerotica obliterans. The extent of fibrosis can often be delineated by palpation of the corpus spongiosum; induration is a sign of scarring associated with the distal stricture process. Calibration of the meatus should be accomplished using a bougie-à-boule approach, not by ultrasonography.
Radiographic assessment
Commonly, retrograde urethrography is performed as the first step in evaluation of an urethral stricture. The data obtained might be limited in the case of distal stricture disease, as the catheter or injection device might obscure the area of interest. In these cases, voiding urethrography might be most helpful, as the obscuring effect of devices employed in retrograde urethrography is not present.7 Additionally the proximal hydrodilatation noted on voiding urethrography tends in some cases to emphasize the narrowed distal segment.
Ultrasonographic evaluation of the urethra has also been described;8, 9 however, the amount of additional information obtained from this procedure compared to that provided by contrast imaging is questionable. Even those clinicians who are most enthusiastic about the efficacy of ultrasonographic urethrography agree that its optimum use is in the evaluation of bulbous strictures.
Endoscopic assessment
Finally, an endoscopic evaluation of the urethra can be carried out to gain information about the degree of spongiofibrosis present. In our experience, use of a rigid pediatric endoscope usually enables the surgeon to traverse the stricture without the need to dilate it, and thereby allows visualization of both ends of the stricture. The information gained at endoscopy, coupled with the palpable findings outlined above, provides significant information on the extent of spongiofibrosis. However, evaluation of this symptom is a matter of gestalt; a thorough evaluation of the entire urethra should always be performed before any treatment is planned, as several segments of the organ might be simultaneously affected.
Management options
The 'reconstructive ladder' principle, in which a progression from simple to complex surgeries is only considered after the failure of several successive interventions, has been applied to treatment of urethral strictures for some time. This approach is, however, archaic in the context of current medical practice. The development of refined reconstructive techniques enables even complex strictures to be treated with the aim of 'curing' the disease. Before any attempt at treatment, however, both physician and patient must arrive at a common understanding in relation to their expectations of treatment outcomes. The presence of comorbidities or personal preference might lead some patients to choose symptomatic management of their stricture disease (by periodic dilation and internal urethrotomy) over potentially curative procedures, such as urethroplasty.
Open reconstruction of the distal urethra also carries two preoperative considerations that are not applicable to strictures in proximal locations: the location of the neomeatus, and reconstruction of the glans penis. The reconstructive surgeon should counsel the patient with regard to the additional challenges of maintaining a patent, functional urethra and a cosmetically acceptable glans before any open procedure is scheduled.
Dilatation
The goal of dilatation is to gently stretch the scar tissue, thereby expanding the urethral lumen, without tearing it or causing further trauma. This aim might be best accomplished by repeated soft dilatation techniques. In our experience, soft catheters or balloon dilators are often best suited to this method of treatment. Ideally, the intervals between treatments should be lengthy to reduce the patient's discomfort and avoid repeated trauma that might contribute to disease progression. We consider that distal urethral strictures might be better suited to protocols that employ periodic self-dilatation than are relatively proximal strictures. In relation to stricture associated with balanitis xerotica obliterans, however, the repeated trauma and inflammation associated with periodic dilation renders this procedure of questionable efficacy compared with a patient-administered chronic dilatation protocol.
Internal urethrotomy
An internal urethrotomy refers to any procedure that incises the scarred urethral tissue. Typically, this approach can be accomplished by cold knife incision or with the use of a laser. This procedure allows the release of contracted scar tissue and expansion of the urethral lumen. For this improvement to be durable, re-epithelialization across the incision must proceed faster than wound contracture. If the area contracts before this process is complete, the stricture essentially recurs. As with dilatation, the goal is to treat abnormal scarred tissues without damaging the underlying healthy tissues, to avoid causing disease progression.
The conflicting success rates of internal urethrotomy reported in the literature might, in part, be the result of differences in selection of patients and definitions of success. In general, a 'cure' rate of 20–30% is attained.10 The procedure is reportedly most successful in highly selected patients with short bulbar strictures (1.0–1.5 cm) and minimal spongiofibrosis. An important point to note is that repeated attempts at urethrotomy do not increase success rates. In fact, many surgeons have described increased procedural difficulty and decreased success at open repair in patients who have undergone multiple urethrotomies.11, 12 Other articles have also refuted the long-held opinion that repeat endoscopic management is safer and more cost-effective than open repair.13, 14, 15 Not all these reports specify the precise urethral location of the strictures treated, but penile and bulbar strictures predominate. The distal urethra is a particularly challenging location for stricture treatment by urethrotomy. This structure is more mobile than the bulbar urethra and the leverage needed to incise the scar is not easily obtained. Additionally, inadvertent incision into the glans penis or corpora cavernosa can cause significant hemorrhage and, possibly, erectile dysfunction. These factors make urethrotomy of questionable efficacy in the treatment of distal urethral strictures.
Open repair techniques
A myriad of open techniques for distal urethral reconstruction have been described.16, 17, 18, 19, 20, 21 Most distal reconstructions can be accomplished with a one-stage technique. The choice of technique is dictated by the specific characteristics of the stricture, its etiology and the preference of the surgeon. Certain principles of reconstructive surgery are paramount to the successful outcome of all these techniques. The scarred tissues should be adequately exposed and excision must be effective. An appropriate choice of tissue should also be made to substitute for that incised by the stricturotomy (see below). All tissues should be handled carefully. The suture lines should be watertight and should not overlap; the choice of suture material is also important. The goal is to create a meatus of adequate caliber. A number of procedures are available to reconstruct the glans penis and glanular urethra (Figure 2).
Figure 2 | Schematic representations of the different techniques of flap meatotomy.
a | Technique of flap meatotomy, after Blandy and Tresidder.17 b | Technique of flap meatotomy, after Cohney.16 c | Flap meatotomy with glans reconstruction and reconstruction of fossa navicularis, after Brannen.19 d | Technique of reconstruction of fossa navicularis and glans reconstruction, after De Sy.18 e | The technique described by Devine, using full-thickness skin-graft 'resurfacing' of the fossa navicularis.20 Original drawings by Robin Reichner Franklin.
Graft urethroplasty
The use of a penile skin graft for reconstruction of the fossa navicularis was described by Devine in 1986 (Figure 2e).20 Since then, the use of buccal mucosa and postauricular skin has also been described as sources of tissue for substitution. Buccal mucosa, a tissue familiar to reconstructive urologists, is well suited to graft procedures owing to its dense subdermal vascular plexus and thick epithelium. It is relatively easy to harvest and to handle, and the site of harvest is cosmetically acceptable. Its use has been well described for repairs of bulbar urethral strictures but use in the distal urethra has been limited. The use of buccal mucosa onlay grafts for staged hypospadias repairs has been the most commonly reported technique.22 Nonetheless, the use of nongenital tissue to repair inflammatory strictures caused by balanitis xerotica obliterans represents a valuable technique. The incorporation of any diseased genital tissue into the repair site would represent a potential nidus for recurrence of the stricture. For this reason, some surgeons advocate a two-stage oral mucosal graft repair of distal urethral strictures caused by balanitis xerotica obliterans (Figure 3).23, 24 In the first stage the oral mucosa is placed (open-faced) in the area of the involved urethra, which has been excised, or occasionally incised (Figure 3a,b). In the second stage, the graft, which is now somewhat mature, is tubularized. This process allows reconstruction and in most cases reconstitution of the glans penis (Figure 3c–e). According to Bracka,24 unless staged oral mucosal graft techniques are used to repair strictures caused by balanitis xerotica obliterans, they will recur, albeit in some cases quite slowly.
Figure 3 | Staged reconstruction of an anterior urethral stricture.
a | The appearance of the penis with the urethra (shaded area shows the location of a tight stenosis of the fossa navicularis that extends into the distal pendulous urethra). b | The distal narrow stricture of the fossa navicularis has been excised, and stricturotomy performed into the normal urethra proximal to the excised tissue. A buccal graft has been applied to the defect, but the bolster dressing has not yet been placed. c | After 6 months, the graft is mature. The illustration shows a Tiersch tube ready for closure. d | The Tiersch tube is closed with a watertight suture line. The distal urethra is usually calibrated to create a urethral lumen of approximately 9.33 mm (28 Fr) diameter. e | Glans reconstruction and closure of the distal shaft has been performed (the shaded area shows the tunica dartos flap, which carries a parietal tunica vaginalis island). The flap was mobilized from the left hemiscrotum in this instance, and transposed to cover the entire area of urethral reconstruction. Original drawings by Robin Reichner Franklin.
Flap urethroplasty
Penile skin flaps have been used in urethral reconstruction procedures for nearly half a century. As it has its own blood supply, the mobilized tissue can be brought in to fill the gap left after stricturotomy without concern for a graft bed. Many different flap procedures have been described, most based on a ventral skin or dartos pedicle graft (Figure 2a–d). The main morbidities associated with these procedures have been flap contraction, necrosis or tethering, any of which can lead to meatal migration or penile torsion. Additionally, penile skin flaps do not perform well when tubularized in a one-stage fashion. For this reason, the most successful use of such flaps has occurred when they have been used in an onlay fashion.
The most readily reproducible and effective modern procedure is perhaps the fasciocutaneous ventral transverse island skin flap, described by Jordan in 1987 (Figure 4).25 This flap is a rectangular ventral skin flap perfused by superficial vessels within the dartos fascia. It is placed ventrally into the defect created by stricturotomy. The glans is closed around the neourethra to make a cosmetically and functionally acceptable distal penis. Again, the results for strictures associated with balanitis xerotica obliterans have not been as impressive as for those of other etiologies. Virasoro et al. studied 35 patients treated using this technique over a mean of 10 years' follow-up.3 A recurrence rate of 50% was seen in patients with strictures associated with balanitis xerotica obliterans, whereas all patients with strictures caused by other etiologies had excellent results. Several modifications of this procedure that employ a circular fasciocutaneous penile skin flap have been described, with reported good results.26, 27
Figure 4 | Technique of reconstruction of the fossa navicularis.
a | The ventral corpus spongiosum is exposed and the urethra opened ventrally through the area of stenosis. A transverse ventral skin island is outlined on the distal penile skin. b | The skin island is elevated on the ventral dartos fascia. c | The skin island is transposed and inverted into the meatotomy defect (d | shows detail). Original drawings by Robin Reichner Franklin. Modified with permission from Schreiter, F. (Ed.) Plastisch-rekonstruktive, Chirurgie in der Urologie, 338–344 © Georg Thieme, Stuttgart, 1999.
As mentioned previously, balanitis xerotica obliterans is a dermatosis; our experience (which supports that of others) suggests that if a stricture is considered likely to have this etiology, skin should not be used as the substitution tissue, either as a graft or flap.
Conclusions
The treatment of urethral strictures has advanced dramatically with our increasing understanding of both the etiology of these strictures and the surgical principles required to achieve successful reconstruction. No longer is a series of repeated, noncurative procedures held to be the standard of treatment. Distal anterior urethral strictures are especially challenging to repair, as both urethral functionality and glanular cosmesis are important to the overall success of the procedure. Careful discussion of the patient's expectations, appropriate selection of graft tissues and consideration of the reconstructive procedures chosen are critical to the long-term success of distal urethral reconstruction.
Review criteria
We performed a MEDLINE review of English language abstracts and full text articles covering all years in the database. The following search terms were used, both alone and in combination: "urethral stricture disease", "anterior urethra", "fossa navicularis", "lichen sclerosis", "urethral dilation", "internal urethrotomy", "buccal mucosa graft", and "penile flap".
