Urethral Strictures


Continuing Education Activity

Urethral strictures cause obstructive urinary symptoms, which can be severe and affect the quality of life. They can be caused by many etiologies and can vary in severity. To avoid significant effects on life activities, urethral strictures should be diagnosed and investigated to offer the best treatment option. This activity describes the etiology, evaluation, and management of urethral strictures and highlights the role of the interprofessional team in providing care for patients with this condition.

Objectives:

  • Describe the etiology and pathophysiology of urethral strictures.
  • Review the appropriate history, physical, and evaluation of urethral strictures.
  • Outline the management and current treatment options for urethral strictures.
  • Summarize interprofessional team strategies for improving care for patients with urethral strictures.

Introduction

A urethral stricture is a narrowing of the urethra, causing obstructive symptoms. They usually result from injury to the urethral mucosa and tissues around it. It can develop anywhere along the length of the male urethra and can be due to many etiologies.[1] It is a common condition resulting in many office and hospital visits and admissions.[2] Urethral strictures can be classified into anterior and posterior, with the anterior ones comprising 92.2%. Most of them occur in the bulbar urethra alone (46.9%), followed by the penile urethra alone (30.5%), or a combined bulbar and penile stricture (9.9%), and finally pan-urethral strictures (4.9%).[3] Urethral strictures can occur in both sexes but are rare in females, which has led to lacking guidelines on how to diagnose and treat female strictures.[4] However, data on male urethral strictures is prevalent, and many treatment options are available. 

The male urethra extends from the external urethral meatus at the tip of the glans penis to the bladder neck proximally. It is contained within the corpus spongiosum, which lies in a groove below the two corpora cavernosa. The inside of the urethra is lined with stratified squamous epithelium. The urethra is divided into anterior (from the external urethral meatus to the distal membranous urethra) and posterior (from the distal membranous urethra to bladder neck) parts. However, the World Health Organization conference in 2002 recommended that this nomenclature should be discarded. According to the new nomenclature, the urethra is broken up into seven segments; the urethral meatus, followed by fossa navicularis, penile, bulbar, membranous, and prostatic urethra, and finally, the bladder neck.[5]

Etiology

The etiology of urethral strictures is divided into four major groups; idiopathic, iatrogenic, inflammatory, and traumatic, with the idiopathic and iatrogenic being the most common at 33% each. Following them are the traumatic causes comprising 19% and finally inflammatory, causing 15% of them.[6] 

With regards to idiopathic causes, there are clinical features that point towards the possibility of them being caused by unrecognized repetitive minor perineal traumas, eventually leading to the stricture.[7]

Iatrogenic causes are divided into five causes. Trans-urethral resections (TUR) comprise 41% of them.[6] During these procedures, the instruments are passed up and down the urethra repeatedly, leading to epithelial injury with stretching the urethra.[8] This urethral injury leads to stricture. Prolonged catheterization (36%) exerts pressure on the urethra leading to pressure necrosis in the epithelium.[6] Changes in the materials used for the make and design of catheters (using silicone instead of latex) has helped in reducing the incidence of strictures. Also, even with the use of intermittent catheterization techniques, strictures still do occur after prolonged periods of use.[5] Cystoscopy (12.7%) causes epithelial injury as well, leading to strictures.[6] Hypospadias repair causes 6.3% of the iatrogenic strictures.[6] Children who undergo repair have a 10% risk of developing urethral strictures later in life.[5] Prostatectomy (3.2%) is another cause of urethral strictures.[6] Urethral strictures complicate the cases of 8.4% of men who undergo treatment for prostate cancer, including prostatectomy, radiotherapy, and chemotherapy, causing stricture in the posterior or bulbar urethra.[9] The direct cause is not very clearly known, whether it is due to instrumental injuries during the procedure or postoperative bladder neck stenosis in the case of radical prostatectomy.[1] 

Inflammatory strictures can be the result of post-infectious inflammation leading to narrowing of the lumen and weakening of the epithelium, most commonly from recurrent gonococcal urethritis. These causes are becoming less common in the developed world due to public education, but some are still common in developing countries.[2] The connection of other infectious causes to urethral strictures is still unclear. There are suggestions that chlamydia, tuberculosis, and schistosomiasis can cause post-infectious inflammation and stricture.[5] Recurrent urinary tract infections (UTIs) can also cause urethral strictures, with the most isolated microorganism being Escherichia coli.[1] Lichen sclerosis (LS) is another cause of inflammatory urethral strictures. The cause and pathophysiology of the disease remain unclear; however, there is a possible genetic predisposition and an autoimmune factor. LS presents as pale, ivory lesions on the glans or vulva and surrounding the anus.[10] The lesions can extend into the urethral meatus and cause obstructive symptoms, leading to high pressure voiding against a narrowed urethra and causing further damage to the epithelium.[5] Inflammatory urethral strictures only affect the anterior part and do not extend to cause posterior urethral strictures.[2] Also, these strictures are significantly longer than the ones caused by other etiologies.[11] 

Post-traumatic anterior urethral strictures most commonly affect the bulbar urethra and are frequently due to straddle injuries compressing the bulbar urethra against the symphysis pubis. This pattern of injury is rarely associated with a pelvic fracture. Penile urethral strictures due to trauma are rare but can happen following a penile fracture.[2] Significant trauma leading to pelvic fracture causes a posterior urethral stricture almost exclusively in the bulbar or membranous urethra (almost 70 % of causes of membranous stenosis is traumatic pelvic future) as they are the site of urethral injury is these scenarios.[1] Although a small fraction of people who sustain a pelvic fracture develop structure (3%-25%), 84% of people with a traumatic posterior stricture have a pelvic fracture.[2] Moreover, post-traumatic urethral strictures tend to be short, with most of them less than four cm in length.[1]

Epidemiology

Urethral strictures are common, with its prevalence in the US being around 200/100,000 in younger men and more than 600/100,000 in men older than 65. The estimated annual incidence rate in The US is 0.9%.[2] Male urethral strictures account for 5,000 hospital admissions annually and 1.5 million visits to clinics.[3] In The UK, the prevalence is considerably less with an estimation of 40/100,000 in men up to 65 years of age and 100/100,000 afterward.[8] Worldwide, it is estimated that male urethral strictures have a prevalence of 229-627/100,000.[12]

Pathophysiology

The pathophysiology is an injury to the urethral epithelium attributed to any of the specific etiologies causing a leak of urine to the corpus spongiosum or by direct trauma to the corpus spongiosum. Either of which initiates inflammation and fibrous changes of the corpus spongiosum. This form of fibrous tissue causes contraction compressing the urethral lumen.[3] These also cause metaplasia of the urethral epithelium to stratified squamous epithelium, which is more affected by pressure changes and stretch causing tears in the mucosa, leading to a further leak of urine into the outer corpus spongiosum, which causes fibrous changes and stricture.[8] This process causes a vicious cycle of strictures and urethral injuries leading to further narrowing of the urethra, and so on.[2]

History and Physical

Most patients present with progressive obstructive voiding symptoms, mostly occurring as a weak stream. However, the severity of the symptoms can vary widely among patients. Especially in patients with slowly progressive or a discrete stricture. These can present with the absence of such symptoms. Usually, in this case, the patient will have detrusor hypertrophy compensating. Other obstructive symptoms can be hesitancy, intermittency, and dribbling.[13] The symptom most associated with strictures is the feeling of incomplete emptying. Patients can present with acute obstruction, more commonly hematuria, and even more commonly UTIs. But overall, 70% of all patients present with obstructive symptoms alone.[8]

Following the initial history taking, additional questioning should be focused on uncovering the underlying etiology. History of interventions, previous infections, and trauma should be sought as well. Finally, appropriate past medical history and comorbidities should be elucidated.[13]

Although that physical examination is usually unrewarding, performing a detailed one is still important. During the physical examination, the clinician should palpate the urethra feeling for any palpable fibrous tissue and look for any skin changes like pale patches pointing towards LS. On some occasions, these patches can be confined only to be surrounding the urethral meatus. Also, identify any scars indicating previous surgery. Examination of the prostate is very important, looking for benign prostatic hyperplasia (BPH), prostatic cancer, or prostatitis.[8][13]

Evaluation

Blood tests do not have a role in diagnosing urethral strictures. However, many lower urinary tract flow studies provide a detailed assessment of the urethra.

Uroflowmetry is the preferred initial investigation. It provides a good assessment of the urethral flow. Also, the interpretation of triphasic uroflowmetry provides data to distinguish patterns of healthy individuals, benign prostatic obstruction, and urethral strictures. A maximum flow (Qmax) of less than 15 mL per second raises the suspicion of lower urinary tract stricture. It is also of importance to study the curve shape to differentiate the cause. Urethral strictures typically produce a plateau at the level of Qmax. Ideally, uroflowmetry studies should be of more than 150mL in volume to yield reliable results.[13][14][15]

Urethroscopy or cystoscopy is a relatively easy and fast investigation to diagnose urethral stricture, and it can be done under local anesthesia (flexible cystoscopy). It helps to determine the location of the stricture. However, it can be of limited use when it is unable to pass through the stricture to assess the length or the state of the urethra proximal to it. In this case, using a smaller caliber ureteroscope can sometimes help pass beyond the stricture and provide more information. Again, another limitation is its inability to provide information about the surrounding fibrosis. So, although it is of limited diagnostic value, it can provide a quick diagnosis in case of clinical doubt.[8][13][15]

Urethrography is the next investigation if the clinical picture and uroflowmetry suggest stricture to confirm the diagnosis. A retrograde urethrography (RUG) can visualize the entire urethra up to the bladder if the patient is relaxed. Frequently, especially when the stricture is significant and insufficient distention of the proximal urethra happens, RUG will not provide sufficient information about the proximal urethra and extent of the stricture. In such cases, a voiding cystourethrography (VCUG) will provide valuable additional information. This is by either asking the patient to void after the bladder is filled with contrast from the RUG or by introducing the contrast through a suprapubic catheter. The combination of RUG and VCUG yields a good image of the entire urethra. It provides information about the location, number, length, and severity of strictures. They are usually the most definitive diagnostic tools. However, these studies have limitations when interpreting the images. This relates to the position of the stricture and the state of the proximal urethra, as these techniques provide a 2D image of a 3D structure.[8][13] Some studies suggest that the use of computed tomography (CT) voiding urethrography or sonoelastography provides better images of the stricture and its characteristics.[16][17]

Ultrasonography (US) is mainly used to assess the bladder and upper urinary tract. It can show a thickened urinary bladder wall. Residual post-voiding urine can be seen on ultrasound as well, which may guide the clinician as to how significant the urethra is obstructed.[8][18] Also, ultrasonography may be useful when directly pointed at the area suspected to assess the presence of spongiofibrosis and possibly visualize the stricture zones when the urethra is filled with a physiologic solution through a Foley catheter.[13]   

Magnetic resonance imaging (MRI) scan use in diagnosing simple urethral strictures is debatable. However, it can provide excellent images when cancer is suspected to be the cause of the stricture, showing the location and extent of the tumor into surrounding tissues.[13]

Treatment / Management

When there are no complications, the treatment’s goal would be symptom relief only. The choice should be based on symptom severity and patient preference. If the symptoms are not troublesome, treatment should not be offered. However, if the patient presents with a complication like recurrent infections or acute retention, treatment would reduce the incidence of complications.[8] The normal urine flow rate in a healthy young male is greater than 15mL/s. Patients with stricture and flow rates between 10-15mL/s usually are asymptomatic. Provided that there is no increased bladder thickness or incomplete emptying, there is no need for any intervention. A flow rate of 5-10 mL/s is usually more associated with obstructive symptoms and complications. But again, this is not always the case. Treatment should only be offered for patients who have troublesome symptoms. If not, active monitoring should be undertaken. If the flow rate is below 5mL/s, there is an increased risk of acute retention, although this is not very common. This group of patients should be offered treatment, even if the symptoms are not significant.[18] In cases where patients present with acute complications, the acute complication should be dealt with first before offering treatment for the stricture. Patients presenting with acute urinary retention should be given a suprapubic bladder fistula. Any existing UTI is treated with antibiotics as well. Once this is dealt with, definitive treatment for the stricture should be undertaken.[15]

Generally speaking, urethral stricture treatment can be divided into transurethral (dilation, internal urethrotomy) and open surgical (stricture resection and anastomosis, urethroplasty, and perineal urethrostomy). It should also be noted that with any of the treatment options, recurrence tends to happen. Especially with long strictures and previously treated ones.[15]

Urethral dilation using sounds and boogies has been the standard and initial treatment modality for a long time. Inserting urethral dilators and sequentially increasing the size leads to stretch and disruption of the stricture. When compared to direct vision internal urethrotomy, there was no demonstrable difference between them with regards to outcomes.[8][18][19] The need for re-treatment within three years for both is around 65%.[20] This procedure is usually performed under local anesthesia and can cause significant discomfort and bleeding. Some studies suggest that the use of balloon dilation would exert a radial force reducing urethral trauma. Initial numbers are pointing towards fewer recurrence rates compared to the previous methods. Sometimes it can be used as a regular dilatation of the urethra using the sounds or the catheter as clean intermittent self-catheterization (CISC) following the internal visual urethrotomy.[20]

Direct vision internal urethrotomy (DVIU) is performed by incising a transurethral incision to release the stricture and leave it to heal by secondary intention, increasing the caliber size of the urethra. It is the first-line treatment of choice for short (<1.5 cm) bulbar strictures with no previous intervention as its highest success rates are with such strictures.[3] As mentioned above, recurrence rates are high and can reach 65% within 3 years.[20] The complication rate after this procedure is 6.5%, with erectile dysfunction being the most common (5%), followed by urinary incontinence (4%), extravasation (3%), UTI (2%), and hematuria (2%). There is a difference in opinion on whether to attempt a repeat DVIU after a recurrence of the first procedure or to go straight to urethroplasty. Some suggest attempting visual internal urethrotomy once more after the first time,[21] while others say that the best option in recurrence is to offer urethroplasty.[19] The explanation for this is that during the procedure, healthy tissue proximal and distal to the stricture has to be excised, resulting in a longer stricture when recurrence happens.[15]

Both of the above-mentioned procedures should be followed by prophylactic antibiotics.[8]

Anastomotic urethroplasty is a more commonly used name for stricture resection and end-to-end anastomosis. It is most appropriate when the stricture is short (<2 cm) and is in the bulbar urethra, which is usually the result of a traumatic straddle-type injury.[2] Preferably, the patient would not have had any previous intervention nor instrumentation as these can worsen the stricture.[22] Here, the urethra is dissected through a perineal approach, the stricture excised, and end-to-end tension-free anastomosis is performed.[15] This is followed by the placement of a Foley catheter that stays in for three weeks and is taken out after a leak-free peri-catheter urethrogram.[22] This procedure is avoided in longer or penile strictures as the loss of urethral length will result in ventral penile curvature. It provides excellent outcomes with success rates of more than 90%.[18][21] The possible complications are erectile dysfunction and stricture recurrence, both at 5%.[22]

Substitution urethroplasty or graft urethroplasty is a procedure where the urethra is mobilized in the area of stricture, dissected from the corpora cavernosa, and opened along the urethra for the entire length of the stricture.[15] This can be achieved through a ventral, dorsal, or lateral approach.[21] Following this, a skin graft is sutured to the defect to create a wider urethra. Skin grafts can be taken from the foreskin, oral mucosa, and rarely form the upper thigh.[15] Theoretically, the oral mucosa provides a more suitable graft material than the skin, mainly due to its histological features and its resistance to urine exposure.[21] However, studies did not show significant superiority of the skin over oral mucosa with regards to success rates, so the donor site is chosen based on the effects on the donor site itself. When the graft is taken from buccal mucosa, pain, stricture, and numbness can happen and lead to considerable discomfort.[15] Some are suggesting the use of lingual mucosa rather than buccal mucosa as it offers fewer complications at the donor site.[23] 

Substitution urethroplasty should be used for bulbar strictures that are too long for anastomotic urethroplasty or any penile urethra stricture.[18][24] When the local conditions are not suitable for a skin graft like scarring from previous surgery, radiotherapy, active infection, or when the stricture is very long, a local skin flap is preferred.[18] In complex urethral strictures like patients who had previous hypospadias repair or urethral reconstruction, or patients with LS, a two-stage approach is preferred.[19][25]. In this technique, stricturotomy is performed, a proximal urethrostomy created, and a skin graft stitched to the urethral plate. Six months later, and if there are no complications, a suprapubic catheter is placed, and the urethra closed over a sound. After three weeks, a voiding trial is performed.[25] Urethroplasty offers a high success rate of more than 85%. Although rare, complications of urethroplasty include erectile dysfunction, UITs, fistulae, incontinence, chordee, and neuropraxia.[3]

Perineal urethrostomy (Boutonnière) is a procedure with palliative intent preserved for patients who have had multiple stricture operations and do not wish to undergo additional surgeries and patients with multiple comorbidities who cannot tolerate a urethroplasty. The bulbar urethra is sutured to the perineal skin with the preservation of sphincter function and continence. Most of the patients who undergo this procedure express high satisfaction with the results.[15]

Differential Diagnosis

As urethral strictures usually present with progressive obstructive symptoms, many other diseases can present similarly. Some of which are:

  • Prostate enlargement, either benign or cancerous. BPH is the commonest cause of weak stream 
  • Prostatitis, in this case, would be associated with burning, frequency, urgency, blood in urine, perineal deep pain (especially when sitting), and cloudy urine with a high prostate-specific antigen (PSA)
  • Underactive bladder, bladder stones, sensory underactivity 
  • Central and peripheral neuropathies
  • Drug-related[26]

Prognosis

As seen from the pathophysiology of urethral strictures, once a stricture is established, it follows a closed circle pattern of increasing fibrosis and worsening stricture. If definitive treatment is not offered, stricture severity will increase gradually, eventually causing complications. However, especially when non-operative management is offered, strictures have high recurrence rates. Surgical management is the treatment option with the best outcomes, with success rates of more than 85%.

Complications

If left untreated, urethral strictures can cause some fo the following complications:

  • Recurrent UTI 
  • Acute urinary retention
  • Bladder diverticulum 
  • Urethrocutaneous fistula 
  • Bilateral vesicoureteric reflux 
  • Unilateral vesicoureteric reflux[27]

Deterrence and Patient Education

Reducing the incidence of urethral strictures would be based on trying to minimize the incidence of causative etiologies.

  • Avoiding pelvic, perineal, and penile trauma. 
  • Educating the patients about the best and safest way to self-catheterize. Advice should include the liberal use of lubricating gel and using the smallest size catheter possible for short periods of time. Also, the least traumatic technique of catheter insertion should be taught and mastered by patients who self-catheterize.  
  • The practice of safe sex is of paramount importance, as gonorrhea was the most causative organism leading to strictures. The effectiveness of this intervention has already been demonstrated in the developed countries where numbers of urethral strictures secondary to gonorrheal urethritis have dropped significantly.[2]

Enhancing Healthcare Team Outcomes

Teamwork is of utmost importance in the prevention, detection, and treatment of urethral strictures. Public education helps reduce the incidence of strictures by educating the public on the causative etiologies and how to prevent them. General practitioners and emergency clinicians should be aware of risk factors and presentation of patients with urethral strictures, providing early intervention when needed. They should also counsel any patient who presents with pelvic, perineal, or penile trauma on how to recognize early signs of urethral strictures and encourage them to seek expert help without delay. When a diagnosis of urethral stricture is made, a team of clinicians, including experienced surgeons, nurses, and social workers, should all work together to provide the most effective and timely advice and treatment. Ideally, in a large-volume center, a specialized interprofessional team should be assembled to care for patients with urethral stricture, as they require expert surgical opinion and treatment and continuous care post-op for a long time.


Article Details

Article Author

Bashar Abdeen

Article Editor:

Almostafa Badreldin

Updated:

1/15/2021 7:53:26 AM

PubMed Link:

Urethral Strictures

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