Posterior urethral valve

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Posterior urethral valve
Prostate - Gray1153.png
Vesiculæ seminales and ampullæ of ductus deferentes, seen from the front. Posterior urethral valves are at the dorsal aspect (back) of the prostatic urethra.
Specialty Urology

Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the urethra and genitourinary system of male newborns. [1] A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal in utero development. It is the most common cause of bladder outlet obstruction in male newborns. The disorder varies in degree, with mild cases presenting late due to milder symptoms. More severe cases can have renal and respiratory failure from lung underdevelopment as result of low amniotic fluid volumes, requiring intensive care and close monitoring. [2] It occurs in about one in 8,000 babies. [3]

Contents

Presentation

PUV can be diagnosed before birth, or even at birth when the ultrasound shows that the male baby has a hydronephrosis. Some babies may also have oligohydramnios due to the urinary obstruction. [4] The later presentation can be a urinary tract infection, diurnal enuresis, or voiding pain.[ citation needed ]

Complications

Diagnosis

Postvesicular obstruction due to urethral valves. Urethralklappe.jpg
Postvesicular obstruction due to urethral valves.

Abdominal ultrasound is of some benefit, but not diagnostic. Features that suggest posterior urethral valves are bilateral hydronephrosis, a thickened bladder wall with thickened smooth muscle trabeculations, and bladder diverticula.[ citation needed ]

Voiding cystourethrogram (VCUG) is more specific for the diagnosis. Normal plicae circularis are variable in appearance and often not seen on normal VCUGs. PUV on voiding cystourethrogram is characterized by an abrupt tapering of urethral caliber near the verumontanum, with the specific level depending on the developmental variant. Vesicoureteral reflux is also seen in over 50% of cases. Very often the posterior urethra maybe dilated thus making the abrupt narrowing more obvious. the bladder wall may show trabeculations or sacculations or even diverticuli.[ citation needed ]

Diagnosis can also be made by cystoscopy, where a small camera is inserted into the urethra for direct visualization of the posteriorly positioned valve. A limitation of this technique is that posterior valve tissue is translucent and can be pushed against the wall of the urethra by inflowing irrigation fluid, making it difficult to visualize. Cystoscopy may also demonstrate the bladder changes.[ citation needed ]

Centers in Europe and Japan have also had excellent results with cystosonography, although it has not been approved for use in the United States yet. [5]

Classification

The male urethra laid open on its anterior (upper) surface. Posterior valves are usually fusion of the plicae colliculi between the entrance of the seminal vesicles at the veromontanum, and extend to the membranous urethra. Gray1142.png
The male urethra laid open on its anterior (upper) surface. Posterior valves are usually fusion of the plicae colliculi between the entrance of the seminal vesicles at the veromontanum, and extend to the membranous urethra.

Posterior urethral obstruction was first classified by H. H. Young in 1919. The verumontanum , or mountain ridge, is a distinctive landmark in the prostatic urethra, important in the systemic division of posterior valve disorders:[ citation needed ]

Dewan has suggested that obstruction in the posterior urethra is more appropriately termed congenital obstructions of the posterior urethral membrane (COPUMs), a concept that has come from an in-depth analysis of the historical papers, and evaluation of patients with a prenatal diagnosis that has facilitated video recording of the uninstrumented obstructed urethra. [7] The congenital obstructive lesions in the bulbar urethra, named Type III Valves by Young in 1919, have been eponymously referred to as Cobb's collar or Moorman's ring. [8] For each of the COPUM (Posterior Urethra) and Cobb's (Bulbar Urethra) lesions, the degree of obstruction can be variable, consistent with a variable expression of the embryopathy. [9] The now nearly one hundred year old nomenclature of posterior urethral valves was based on limited radiology and primitive endoscopy, thus a change COPUM or Cobb's has been appropriate.[ citation needed ]

Treatment

If suspected antenatally, a consultation with a paediatric surgeon/ paediatric urologist maybe indicated to evaluate the risk and consider treatment options.[ citation needed ]

The most important first treatment in a newborn baby boy is to relieve the bladder with urethral catheter or suprapubic drainage. [10]

Treatment is by endoscopic valve ablation. Fetal surgery is a high risk procedure reserved for cases with severe oligohydramnios, to try to limit the associated lung underdevelopment, or pulmonary hypoplasia, that is seen at birth in these patients. The risks of fetal surgery are significant and include limb entrapment, abdominal injury, and fetal or maternal death. Specific procedures for in utero intervention include infusions of amniotic fluid, serial bladder aspiration, and creating a connection between the amniotic sac and the fetal bladder, or vesicoamniotic shunt. [5]

There are three specific endoscopic treatments of posterior urethral valves:[ citation needed ]

The standard treatment is primary (transurethral) ablation of the valves. [11] Urinary diversion is used in selected cases, [11] and its benefit is disputed. [12] [13]

Following surgery, the follow-up in patients with posterior urethral valve syndrome is long term, and often requires a multidisciplinary effort between paediatric surgeons/ paediatric urologists, paediatric nephrologists, pulmonologists, neonatologists, radiologists and the family of the patient. Care must be taken to promote proper bladder compliance and renal function, as well as to monitor and treat the significant lung underdevelopment that can accompany the disorder. Definitive treatment may also be indicated for the vesico-ureteral reflux.[ citation needed ]

Female homolog

Vector diagram of posterior urethral obstruction causing severe bilateral hydronephrosis and bladder trabeculation Posterior Urethral Valve.svg
Vector diagram of posterior urethral obstruction causing severe bilateral hydronephrosis and bladder trabeculation

The female homolog to the male verumontanum from which the valves originate is the hymen.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Urinary system</span> Human anatomical system consisting of the kidneys, ureters, urinary bladder, and the urethra

The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine. The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary system are very similar, differing only in the length of the urethra.

<span class="mw-page-title-main">Urinary catheterization</span> Insertion of a catheter through the urethra to drain urine

In urinary catheterization a latex, polyurethane, or silicone tube known as a urinary catheter is inserted into the bladder through the urethra to allow urine to drain from the bladder for collection. It may also be used to inject liquids used for treatment or diagnosis of bladder conditions. A clinician, often a nurse, usually performs the procedure, but self-catheterization is also possible. A catheter may be in place for long periods of time or removed after each use.

<span class="mw-page-title-main">Urethral stricture</span> Medical condition

A urethral stricture is a narrowing of the urethra, the tube connected to the bladder that allows the passing of urine. The narrowing reduces the flow of urine and makes it more difficult or even painful to empty the bladder.

Oligohydramnios is a medical condition in pregnancy characterized by a deficiency of amniotic fluid, the fluid that surrounds the fetus in the abdomen, in the amniotic sac. It is typically diagnosed by ultrasound when the amniotic fluid index (AFI) measures less than 5 cm or when the single deepest pocket (SDP) of amniotic fluid measures less than 2 cm. Amniotic fluid is necessary to allow for normal fetal movement, lung development, and cushioning from uterine compression. Low amniotic fluid can be attributed to a maternal, fetal, placental or idiopathic cause and can result in poor fetal outcomes including death. The prognosis of the fetus is dependent on the etiology, gestational age at diagnosis, and the severity of the oligohydramnios.

Potter sequence is the atypical physical appearance of a baby due to oligohydramnios experienced when in the uterus. It includes clubbed feet, pulmonary hypoplasia and cranial anomalies related to the oligohydramnios. Oligohydramnios is the decrease in amniotic fluid volume sufficient to cause deformations in morphogenesis of the baby.

Urinary tract obstruction is a urologic disease consisting of a decrease in the free passage of urine through one or both ureters and/or the urethra. It is a cause of urinary retention. Complete obstruction of the urinary tract requires prompt treatment for renal preservation. Any sign of infection, such as fever and chills, in the context of obstruction to urine flow constitutes a urologic emergency.

<span class="mw-page-title-main">Hydronephrosis</span> Medical condition

Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of the entire upper urinary tract.

<span class="mw-page-title-main">Urostomy</span>

A urostomy is a surgical procedure that creates a stoma for the urinary system. A urostomy is made to avail for urinary diversion in cases where drainage of urine through the bladder and urethra is not possible, e.g. after extensive surgery or in case of obstruction.

<span class="mw-page-title-main">Mitrofanoff procedure</span>

The Mitrofanoff procedure, also known as the Mitrofanoff appendicovesicostomy, is a surgical procedure in which the appendix is used to create a conduit, or channel, between the skin surface and the urinary bladder. The small opening on the skin surface, or the stoma, is typically located either in the navel or nearby the navel on the right lower side of the abdomen. Originally developed by Professor Paul Mitrofanoff in 1980, the procedure represents an alternative to urethral catheterization and is sometimes used by people with urethral damage or by those with severe autonomic dysreflexia. An intermittent catheter, or a catheter that is inserted and then removed after use, is typically passed through the channel every 3–4 hours and the urine is drained into a toilet or a bottle. As the bladder fills, rising pressure compresses the channel against the bladder wall, creating a one-way valve that prevents leakage of urine between catheterizations.

<span class="mw-page-title-main">Vesicoureteral reflux</span> Medical condition

Vesicoureteral reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the renal calyx or kidneys. Urine normally travels in one direction from the kidneys to the bladder via the ureters, with a one-way valve at the vesicoureteral (ureteral-bladder) junction preventing backflow. The valve is formed by oblique tunneling of the distal ureter through the wall of the bladder, creating a short length of ureter (1–2 cm) that can be compressed as the bladder fills. Reflux occurs if the ureter enters the bladder without sufficient tunneling, i.e., too "end-on".

In urology, voiding cystourethrography (VCUG) is a frequently performed technique for visualizing a person's urethra and urinary bladder while the person urinates (voids). It is used in the diagnosis of vesicoureteral reflux, among other disorders. The technique consists of catheterizing the person in order to fill the bladder with a radiocontrast agent, typically diatrizoic acid. Under fluoroscopy the radiologist watches the contrast enter the bladder and looks at the anatomy of the patient. If the contrast moves into the ureters and back into the kidneys, the radiologist makes the diagnosis of vesicoureteral reflux, and gives the degree of severity a score. The exam ends when the person voids while the radiologist is watching under fluoroscopy. Consumption of fluid promotes excretion of contrast media after the procedure. It is important to watch the contrast during voiding, because this is when the bladder has the most pressure, and it is most likely this is when reflux will occur. Despite this detailed description of the procedure, at least as of 2016 the technique had not been standardized across practices.

A ureteral stent, or ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney. The length of the stents used in adult patients varies between 24 and 30 cm. Additionally, stents come in differing diameters or gauges, to fit different size ureters. The stent is usually inserted with the aid of a cystoscope. One or both ends of the stent may be coiled to prevent it from moving out of place; this is called a JJ stent, double J stent or pig-tail stent.

Urinary diversion is any one of several surgical procedures to reroute urine flow from its normal pathway. It may be necessary for diseased or defective ureters, bladder or urethra, either temporarily or permanently. Some diversions result in a stoma.

<span class="mw-page-title-main">Seminal colliculus</span>

The seminal colliculus, or verumontanum, of the prostatic urethra is a landmark distal to the entrance of the ejaculatory ducts. Verumontanum is translated from Latin to mean 'mountain ridge', a reference to the distinctive median elevation of urothelium that characterizes the landmark on magnified views. Embryologically, it is derived from the uterovaginal primordium. The landmark is important in classification of several urethral developmental disorders. The margins of seminal colliculus are the following:

<span class="mw-page-title-main">Ureterostomy</span>

A ureterostomy is the creation of a stoma for a ureter or kidney.

Urethroplasty is the surgical repair of an injury or defect within the walls of the urethra. Trauma, iatrogenic injury and infections are the most common causes of urethral injury/defect requiring repair. Urethroplasty is regarded as the gold standard treatment for urethral strictures and offers better outcomes in terms of recurrence rates than dilatations and urethrotomies. It is probably the only useful modality of treatment for long and complex strictures though recurrence rates are higher for this difficult treatment group.

<span class="mw-page-title-main">Prostatic stent</span> Type of stent

A prostatic stent is a stent used to keep open the male urethra and allow the passing of urine in cases of prostatic obstruction and lower urinary tract symptoms (LUTS). Prostatic obstruction is a common condition with a variety of causes. Benign prostatic hyperplasia (BPH) is the most common cause, but obstruction may also occur acutely after treatment for BPH such as transurethral needle ablation of the prostate (TUNA), transurethral resection of the prostate (TURP), transurethral microwave thermotherapy (TUMT), prostate cancer or after radiation therapy.

Bladder outlet obstruction occurs when urine is unable to flow from the kidneys through the ureters and out of the bladder through the urethra. Decreased flow of urine leads to swelling of the urinary tract, called hydronephrosis. This process of decreased flow of urine through the urinary tract can begin as early as during intrauterine life and it prevents normal development of fetal kidneys and fetal urine. Low levels of fetal urine leads to low amniotic fluid levels and incomplete lung maturation. Older children and adults can also experience bladder outlet obstruction; however, this process is usually reversible and isn't associated with as many poor outcomes as in infants with congenital bladder outlet obstruction.

<span class="mw-page-title-main">Duplicated ureter</span>

Duplicated ureter or Duplex Collecting System is a congenital condition in which the ureteric bud, the embryological origin of the ureter, splits, resulting in two ureters draining a single kidney. It is the most common renal abnormality, occurring in approximately 1% of the population.

References

  1. ↑ Manzoni C, Valentini A (2002). "Posterior urethral valves". Rays. 27 (2): 131–4. PMID   12696266.
  2. ↑ "Emedicine - Posterior urethral valves - overview and treatment". Emedicine. Retrieved July 26, 2010.
  3. ↑ "Posterior urethral valves - Disease Information". Children's hospital, Boston. Archived from the original on May 19, 2011. Retrieved January 31, 2011.
  4. ↑ Klaassen, I.; Neuhaus, T. J.; Mueller-Wiefel, D. E.; Kemper, M. J. (2006). "Antenatal oligohydramnios of renal origin: long-term outcome". Nephrology Dialysis Transplantation. 22 (2): 432–439. doi: 10.1093/ndt/gfl591 . ISSN   0931-0509. PMID   17065192.
  5. 1 2 "Emedicine - Posterior Urethral Valves - Diagnosis and Treatment". Emedicine. Archived from the original on July 8, 2012. Retrieved July 18, 2010.
  6. ↑ "Nationwide Children's Hospital, Radiology - Posterior urethral valves". Nationwide Children's Hospital. Retrieved July 26, 2010.
  7. ↑ Dewan, Paddy (2014-07-19). "Posterior Urethral Obstruction: COPUM". Bangladesh Journal of Endosurgery. 2 (1): 29–32. doi: 10.3329/bje.v2i1.19590 . ISSN   2306-4390.
  8. ↑ "Nationwide Children's Hospital, Radiology - Cobb's Collar". Nationwide Children's Hospital. Retrieved July 26, 2010.
  9. ↑ Dewan, PA; Goh, DW (1995). "Variable expression of the congenital membrane of the posterior urethra". Urology. 45 (3): 507–509 1995. doi:10.1016/s0090-4295(99)80024-7. PMID   7879340.
  10. ↑ Rink, Richard C.; Mouriquand, Pierre D. E. (2010). Pediatric Urology. ISBN   978-1-4160-3204-5.
  11. 1 2 Warren J, Pike JG, Leonard MP (April 2004). "Posterior urethral valves in Eastern Ontario - a 30 year perspective". Can J Urol. 11 (2): 2210–5. PMID   15182412.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ↑ Kim YH, Horowitz M, Combs A, Nitti VW, Libretti D, Glassberg KI (August 1996). "Comparative urodynamic findings after primary valve ablation, vesicostomy or proximal diversion". J. Urol. 156 (2 Pt 2): 673–6. doi:10.1097/00005392-199608001-00028. PMID   8683757.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ↑ Smith GH, Canning DA, Schulman SL, Snyder HM, Duckett JW (May 1996). "The long-term outcome of posterior urethral valves treated with primary valve ablation and observation". J Urol. 155 (5): 1730–4. doi:10.1016/S0022-5347(01)66186-X. PMID   8627873.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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