Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra ...

and

genitourinary system The genitourinary system, or urogenital system, are the organs of the reproductive system and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common path ...

of male newborns. A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal ''

in utero ''In Utero'' is the third and final studio album by American rock band Nirvana. It was released on September 21, 1993, by DGC Records. After breaking into the mainstream with their second album, ''Nevermind'' (1991), Nirvana hired Steve Albin ...

'' 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 The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

and

respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise ...

from lung underdevelopment as result of low amniotic fluid volumes, requiring

intensive care Intensive care medicine, also called critical care medicine, is a medical specialty that deals with seriously or critically ill patients who have, are at risk of, or are recovering from conditions that may be life-threatening. It includes pro ...

and close monitoring. It occurs in about one in 8,000 babies.

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. The later presentation can be a urinary tract infection, diurnal enuresis, or voiding pain.

Complications

Incontinence Incontinence or Incontinent may refer to: *Fecal incontinence, the involuntary excretion of bowel contents * Urinary incontinence, the involuntary excretion of urine * Lack of moderation or self-control, especially related to sexual desire - see ...

Urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...

Renal failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...

Vesicoureteral reflux 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 directio ...

Chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

Oligohydramnios 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 ( ...

Diagnosis

Abdominal

ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...

is of some benefit, but not diagnostic. Features that suggest posterior urethral valves are bilateral hydronephrosis, a thickened bladder wall with thickened

smooth muscle Smooth muscle is an involuntary non- striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit ...

trabeculations, and bladder

diverticula In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...

Voiding cystourethrogram 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 (kidney reflux), am ...

(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 The seminal colliculus (Latin ''colliculus seminalis''), or verumontanum, of the prostatic urethra is a landmark distal to the entrance of the ejaculatory ducts (on both sides, corresponding vas deferens and seminal vesicle feed into corresponding ...

, with the specific level depending on the developmental variant.

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. Diagnosis can also be made by

cystoscopy Cystoscopy is endoscopy of the urinary bladder via the urethra. It is carried out with a cystoscope. The urethra is the tube that carries urine from the bladder to the outside of the body. The cystoscope has lenses like a telescope or microscop ...

, 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

by inflowing irrigation fluid, making it difficult to visualize. Cystoscopy may also demonstrate the bladder changes. 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.

Classification

Posterior urethral obstruction was first classified by H. H. Young in 1919. The ''

'', or mountain ridge, is a distinctive landmark in the prostatic urethra, important in the systemic division of posterior valve disorders: * Type I - Most common type; due to anterior fusing of the ''plicae colliculi'', mucosal fins extending from the bottom of the verumontanum distally along the prostatic and membranous urethra * Type II - Least common variant; vertical or longitudinal folds between the verumontanum and proximal prostatic urethra and bladder neck * Type III - Less common variant; a disc of tissue distal to verumontanum, also theorized to be a developmental anomaly of congenital urogenital remnants in the bulbar urethra 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. The congenital obstructive lesions in the bulbar urethra, named Type III Valves by Young in 1919, have been

eponymous An eponym is a person, a place, or a thing after whom or which someone or something is, or is believed to be, named. The adjectives which are derived from the word eponym include ''eponymous'' and ''eponymic''. Usage of the word The term ''epon ...

ly referred to as Cobb's collar or Moorman's ring. 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. 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.

Treatment

If suspected antenatally, a consultation with a paediatric surgeon/ paediatric urologist maybe indicated to evaluate the risk and consider treatment options. Treatment is by endoscopic valve ablation. Fetal surgery is a high risk procedure reserved for cases with severe

oligohydramnios 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 ( ...

, to try to limit the associated lung underdevelopment, or

pulmonary hypoplasia Pulmonary hypoplasia is incomplete development of the lungs, resulting in an abnormally low number or size of bronchopulmonary segments or alveoli. A congenital malformation, it most often occurs secondary to other fetal abnormalities that i ...

, 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 The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products between ...

, serial bladder aspiration, and creating a connection between the amniotic sac and the fetal bladder, or vesicoamniotic shunt. There are three specific endoscopic treatments of posterior urethral valves: * Vesicostomy followed by valve ablation - a

stoma In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bo ...

, or hole, is made in the

urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine ente ...

, also known as ''low diversion'', after which the valve is ablated and the stoma is closed. * Pyelostomy followed by valve ablation - stoma is made in the pelvis of the kidney as a slightly ''high diversion'', after which the valve is ablated and the stoma is closed * Primary (transurethral) valve ablation - the valve is removed through the urethra without creation of a stoma The standard treatment is primary (transurethral) ablation of the valves. Urinary diversion is used in selected cases, and its benefit is disputed. 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 Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiati ...

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.

Female homolog

The

female Female ( symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Fema ...

homolog In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of prima ...

to the

male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot reproduce sexually without access to ...

from which the valves originate is the

hymen The hymen is a thin piece of mucosal tissue that surrounds or partially covers the external vaginal opening. It forms part of the vulva, or external genitalia, and is similar in structure to the vagina. In children, a common appearance of the ...

References

External links

{{Congenital malformations of urinary system Congenital disorders of urinary system Pediatrics