(尿通過障害を来す小児男子の疾患)後部尿道弁

WordNet

control consisting of a mechanical device for controlling the flow of a fluid
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
one of the paired hinged shells of certain molluscs and of brachiopods
the entire one-piece shell of a snail and certain other molluscs
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
located at or near or behind a part or near the end of a structure
duct through which urine is discharged in most mammals and which serves as the male genital duct
of or relating to the urethra
(of brass instruments) having valves

PrepTutorEJDIC

(液体・ガスなどの流れを調節する)『バルブ』,弁 / (血液の流れを調節する)弁,弁膜 / (管楽器の)バルブ / (2枚貝の)から,貝がら / 《英》真空管
《名詞の前にのみ用いて》(生物学的に,位置が)後ろの,後部の / (時間・順序が)後の;(…より)後の《+『to』+『名』》(later) / しり(buttocks)
尿道

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/11/11 20:40:44」(JST)

wiki en

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 followed conservatively. 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 8000 babies.^[3]

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Video explanation

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.

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:

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^[4]
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.^[5] 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.^[6] 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.^[7] 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.

Diagnosis

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.

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.

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.

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.^[8]

Treatment

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.^[8]

There are three specific endoscopic treatments of posterior urethral valves:

Vesicostomy followed by valve ablation - a stoma, or hole, is made in the urinary bladder, 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.^[9] Urinary diversion is used in selected cases,^[9] and its benefit is disputed.^[10]^[11]

Following surgery, the follow-up in patients with posterior urethral valve syndrome is long term, and often requires a multidisciplinary effort between urologists, 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.

Complications

Incontinence
Urinary tract infection
Renal failure
Vesicoureteral reflux
Chronic kidney disease

Female homolog

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.

References

^ Manzoni C, Valentini A (2002). "Posterior urethral valves". Rays. 27 (2): 131–4. PMID 12696266.
^ "Emedicine - Posterior urethral valves - overview and treatment". Emedicine. Retrieved July 26, 2010.
^ "Posterior urethral valves - Disease Information". Children's hospital, Boston. Retrieved January 31, 2011.
^ "Nationwide Children's Hospital, Radiology - Posterior urethral valves". Nationwide Children's Hospital. Retrieved July 26, 2010.
^ 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.
^ "Nationwide Children's Hospital, Radiology - Cobb's Collar". Nationwide Children's Hospital. Retrieved July 26, 2010.
^ Dewan, PA; Goh, DW. "Variable expression of the congenital membrane of the posterior urethra". Urology. 45: 507–509 1995. doi:10.1016/s0090-4295(99)80024-7.
^ ^a ^b "Emedicine - Posterior Urethral Valves - Diagnosis and Treatment". Emedicine. Retrieved July 18, 2010. ^{[dead link]}
^ ^a ^b Warren J, Pike JG, Leonard MP. Posterior urethral valves in Eastern Ontario - a 30 year perspective. Can J Urol. 2004 Apr;11(2):2210-5. PMID 15182412.
^ Kim YH, Horowitz M, Combs A, Nitti VW, Libretti D, Glassberg KI. Comparative urodynamic findings after primary valve ablation, vesicostomy or proximal diversion. J Urol. 1996 Aug;156(2 Pt 2):673-6. PMID 8683757.
^ Smith GH, Canning DA, Schulman SL, Snyder HM 3rd, Duckett JW. The long-term outcome of posterior urethral valves treated with primary valve ablation and observation. J Urol. 1996 May;155(5):1730-4. PMID 8627873.

UpToDate Contents

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1. 後部尿道弁の臨床症状および診断 clinical presentation and diagnosis of posterior urethral valves
2. 後部尿道弁のマネージメント management of posterior urethral valves
3. 先天性腎尿路異常（CAKUT）の評価 evaluation of congenital anomalies of the kidney and urinary tract cakut
4. 小児における膀胱機能障害の評価および診断 evaluation and diagnosis of bladder dysfunction in children
5. 胎児水腎症の産後マネージメント postnatal management of antenatal hydronephrosis

English Journal

Congenital Anomalies of the Kidney and the Urinary Tract (CAKUT).

Rodriguez MM.
Fetal and pediatric pathology.Fetal Pediatr Pathol.2014 Oct 14. [Epub ahead of print]
This article reviews the majority of Congenital Anomalies of the Kidney and Urinary Tract (CAKUT) with emphasis in Pediatric Pathology describing and illustrating lesions as varied as ureteral duplications, ureteropelvic junction obstruction, horseshoe kidney, posterior urethral valve and prune bell
PMID 25313840

Laser Ablation in the Management of Obstructive Uropathy in Neonates.

Pagano MJ1, van Batavia JP, Casale P.
Journal of endourology / Endourological Society.J Endourol.2014 Sep 5. [Epub ahead of print]
Abstract Introduction: Endoscopic management of posterior urethral valves and congenital ureteroceles is the current standard to relieve the obstruction. While the most commonly used techniques involve cystoscopic incision with cold knife or electrosurgery, an alternative is to ablate the obstructiv
PMID 25046584

Anterior urethral valve associated with posterior urethral valves: report of 2 cases and review of the literature.

Tran CN1, Reichard CA2, McMahon D1, Rhee A1.
Urology.Urology.2014 Aug;84(2):469-71. doi: 10.1016/j.urology.2014.04.034. Epub 2014 Jun 21.
Anterior urethral valve (AUV) associated with posterior urethral valves (PUVs) is an extremely rare congenital urologic anomaly resulting in lower urinary tract obstruction. We present our experience with 2 children with concomitant AUV and PUV as well as a literature review. The clinical presentati
PMID 24958476

Japanese Journal

後部尿道弁と経尿道的内視鏡切開術 (特集小児泌尿器科内視鏡手術"最前線" : 適応とコツ) -- (内視鏡手術)

臨床泌尿器科 = Japanese journal of clinical urology 69(2), 119-127, 2015-02
NAID 40020342591

CAKUT(congenital anomalies of the kidney and urinary tract)に対する画像検査—排尿時膀胱尿道造影(VCUG)と核医学検査—

日本小児腎臓病学会雑誌 26(1), 33-42, 2013
NAID 130003384552

Urinary ascites in a fetus with posterior urethral valve : Antenatal diagnosis

Pediatrics international : official journal of the Japan Pediatric Society 53(2), 281-282, 2011-04-01
NAID 10029558118

Related Pictures

★リンクテーブル★

リンク元	「後部尿道弁」
関連記事	「posterior」「urethral」「valve」

「後部尿道弁」

Posterior urethral valve
	Vesiculæ seminales and ampullæ of ductus deferentes, seen from the front. Posterior urethral valves are at the dorsal aspect (back) of the prostatic urethra.
Classification and external resources
DiseasesDB	34137
eMedicine	ped/2357 radio/572
	[edit on Wikidata]

　　[★]

英: posterior urethral valve
関: 尿道弁、先天性水腎症

概念

男子後部尿道の精丘の両脇に発生する線維筋性組織からなる膜状構造物が排尿時に弁状に作用することで排尿障害を来す病態。
重症度は弁の構造により様々であり、高度の障害では新生児期より尿路感染・腎機能障害を来すが、軽症例では幼児期・学童期に尿路感染・排尿習慣異常・夜尿症を契機に発見される。
排尿時膀胱尿道造影で、後部尿道の拡張、膀胱の変形、膀胱尿管逆流と共に上部尿路の拡張が見られる。
治療は経尿道的切開を行うが、改善しない場合には膀胱皮膚瘻や尿管皮膚瘻が行われる。