Overview

When a child has posterior urethral stenosis, the urethra narrows in the highest region, impairing normal urine flow. It can be caused by factors like pelvic fractures, prior treatments for prostate cancer, or congenital issues. Symptoms include difficulty urinating, urinary tract infections, bloody urine and abdominal pain.

Diagnosis involves tests like ureteroscopy and retrograde urethrogram. Treatment options include open surgery to remove scar tissue and suture healthy ends of the urethra, or urethrotomy to cut and enlarge the stenosis. Regular follow-up is crucial as stenosis can recur. Prevention involves avoiding injuries like pelvic fractures. Collaborative care involving paediatricians, urologists and nephrologists is essential for managing this condition effectively.

Introduction

One of the most frequent causes of urinary tract obstruction in children is posterior urethral valves. These are exclusive to patients assigned male at birth (amab) and block membrane folds in the posterior urethral lumen.¹ Trauma is the primary cause of posterior urethral strictures in children, with pelvic fractures frequently serving as an underlying cause. The treatment of urethral strictures in children often involves surgery, particularly anastomotic repair, the outcome of which varies depending on the particulars of each case.²

Anatomy of the urethra

The urethra is divided into the anterior and posterior segments by the urogenital diaphragm. The posterior urethra consists of the membranous urethra enclosed in the urogenital diaphragm, and the prostatic urethra, while the anterior part is formed by the bulbar and penile urethra.³

Posterior urethral valves are small leaflets of tissue in the urethra that can block urine flow. Urethral stricture refers to a narrowing of the urethra which can restrict urine flow and mainly affects people amab. Urethral prolapse, more common in individuals assigned female at birth (afab), involves the inner lining of the urethra protruding through the urethral opening, often causing minimal symptoms but may lead to bleeding.⁴

Aetiology and pathophysiology of urethral stenosis

Urinary tract blockage is brought on by posterior urethral valves. Acute urine retention during delivery may indicate posterior urethral valves, depending on the degree of obstruction.¹ Hypertrophy of the bladder wall and detrusor muscle may result from obstruction brought on by posterior urethral valves. Modifications to the bladder can cause changes in intravesical pressure, bladder fullness and compliance. Vesicoureteric reflux is a condition when high bladder pressure is transferred into the ureters.This is linked to infection, urinary incontinence and gradually declining kidney function. Severe cases of low urine production might result in pulmonary hypoplasia due to oligohydramniosis.⁵

Moreover, the impact of posterior urethral valves extends beyond the urinary system, as severe cases with low urine production can lead to pulmonary hypoplasia due to oligohydramnios, highlighting the potential systemic consequences of this condition on foetal development.

Mechanisms leading to urethral narrowing

The mechanisms causing urethral stricture or narrowing of the urethra entail damage to the urethral epithelium, which can be caused by a number of things, including infections, trauma or medical procedures like catheterization. This injury causes the tissue to become inflamed and fibrous, which causes the urethra to scar and restrict. The urethra contracts as a result of the accumulation of fibrous tissue, squeezing the lumen and preventing urine passage.

Furthermore, the urethral epithelium may develop metaplasia into stratified squamous epithelium which increases the tissue's sensitivity to pressure fluctuations and trauma and promotes the formation of strictures. Urine function is impacted by this process, which also causes a cycle of strictures and urethral obstruction that may result in infections and urine retention.⁶

Scar tissue formation in the urethra as a result of prior urethral injury or surgery is the primary mechanism responsible for urethral narrowing, sometimes referred to as urethral strictures, in children. The natural passage of urine from the bladder may be obstructed by this scar tissue, which may result in a number of symptoms and possible consequences.⁷

Clinical presentation of urethral stenosis

In a study involving paediatric patients aged 1 day to 8 years, the following symptoms were observedof the 37 (100%) individuals with voiding dysfunction, the most common clinical characteristics were fever with a core temperature greater than 38°C (n = 7: 18.9%) and suprapubic distention from palpable bladder in 36 (97.3%) of the patients, failure to thrive (n = 6: 16.2%), ascites (n = 4: 10.8%), and ballotable kidneys (n = 11: 29.7%), of which 7 (7/11; 63.6%) were bilateral. Three patients each had hematuria, patent urachus, and hiccups, and eleven patients (29.7%) had anemia (hematochrit <30%) at presentation.⁸

• Fever
• Suprapubic distention
• Failure to thrive
• Ascites
• Haematuria
• Ballotable kidneys
• Anaemia

A further study found these symptoms

Using urine microscopy and culture, Klebsiella genus, mixed growth, Escherichia coli, Pseudomonas, and Staphylococcus aureus, were the most frequently isolated bacteria. Other patients having varied degrees of hydronephrosis, hydroureters, and thick wall bladders, abdomino-pelvic ultrasonography was performed on the majority of patients.⁹

Prognosis for urethral stenosis

The prognosis in urethral stenosis varies by the extent of obstruction and the consequences that occur during pregnancy. Many infants who survive the newborn period continue to experience bladder dysfunction and the majority go on to develop chronic kidney disease (CKD).¹⁰

The prognosis for urethral stricture is generally positive as it is a treatable condition. However, there is a possibility of recurrence after treatment. 

Regular follow-up with a urologist is recommended, especially since strictures can come back after surgery. The outcome can vary depending on the severity of the stricture and the chosen treatment plan. It is crucial to address any symptoms promptly and seek appropriate medical care to manage urethral strictures effectively.

Management strategies

Non-surgical approaches 

Managing posterior urethral stenosis in children can be difficult, but some of the non-surgical methods are dilation and urethral stents.

Urethral dilatation and urethral stent usage are two non-surgical methods for treating pediatric urethral strictures. It is crucial to remember that these non-surgical techniques cannotalways produce the best results and might occasionally necessitate the use of further surgical procedures. 

Poor outcomes of urethral dilatation and internal urethrotomies in childrenfrequently require additional surgical procedures so these procedures are typically not advised. 

More invasive procedures like transpubic urethroplasty or replacement techniques may be necessary in children when non-surgical approaches are insufficient to produce a tension-free anastomosisSurgical interventions.

Paediatric patients must undergo a new evaluation prior to postponed repair in order to determine the location and length of the urethral defect, the anatomy of the anterior urethra, the shape of the bladder neck, and the presence of any local problems like fistulas, pseudo diverticula, or stones.¹¹ Although early surgical exploration and suture repair have been suggested in the past, they are challenging to carry out because of the patient's critical condition and the urologists' inexperience treating such serious urethral injuries.¹²

Endoscopic realignment, is a method that allows the urologist to find incomplete urethral rips that can be quickly stented. However, the majority of patients need several surgeries and long-term documented results with this course of treatment are poor in children.

Despite these limitations, it is generally accepted that early endoscopic realignment should only be performed on paediatric patients in the following circumstances: 

• when there is a significant urethral distraction defect
• when there is also a concurrent bladder neck tear
• when there is a rectal laceration that needs to be sutured²

Most urologists prefer to do a suprapubic cystostomy followed by postponed urethral reconstruction due to ongoing advancements in surgical procedures that can cure posttraumatic urethral distraction abnormalities with good postoperative results, low incidence of impotence, and incontinence. A suprapubic cystotomy reduces the danger of significant blood loss in a severely sick child and effectively drains the bladder without disturbing the pelvic hematoma.The primary disadvantage is the extended duration of the patient's cystostomy prior to the final surgical repair.²

Complications and challenges

An important part of managing children with posterior urethral valves (PUV) is taking into account the long-term effects and follow-up issues. TThese patients need to have close follow-up, sometimes for the rest of their lives.¹³ If PUV is not adequately controlled, long-term effects may include problems like growth failure, declining renal function and recurring urinary tract infections.¹³ Antenatal diagnosis is crucial for improving prognosis since it enables prompt interventionto lower the condition's related morbidity.¹³

Summary

Several important factors are highlighted in the research on posterior urethral stenosis in children. Understanding the origins and features of posterior urethral strictures is crucial since trauma, especially that connected to pelvic fractures, is a common source of these strictures in infants. Although there are several obstacles to treating traumatic posterior urethral stenosis in children, frequent surgical methods include excision and end-to-end anastomotic urethroplasty, transpubic urethroplasty, and tubed penile fasciocutaneous flap.

Although there are few long-term outcome studies, follow-up is important to watch for problems such as worsening renal function and recurring urinary tract infections. Furthermore, studies highlight the significance of precise imaging methods such as magnetic resonance imaging (MRI) in determining the extent of the ailment and directing therapeutic interventions.