Incidence: 1/5000 to 1/8000 male births. It is the most common cause (64 %) of obstruction to the flow of urine during fetal life; it is one of the causes of LUTO (acronym for Lower Urinary Tract Obstruction). This is the persistence of mucous folds in the prostate urethra. 

The consequences are already present during intrauterine life in various forms, often recognizable by fetal ultrasound:

-        uréterohydronephrosis

-        oligoamnios often associated when severe, with pulmonary hypoplasia

-        sometimes ascites.

Some teams insert a vesicoamniotic drain in utero to decompress the urinary tract. When the diagnosis has been made antenatally, an urethral or suprapubic catheter is placed at birth while waiting for curative surgery. In the absence of antenatal diagnosis, the diagnosis is difficult in the neonate because the symptomatology is often crude; the condition may  be uncovered later following early, frequent, recurrent urinary tract infections, and advanced signs of renal failure (loss of the power of concentration of urine, elevation of serum creatinine) are sometimes already present. The most suggestive sign is dripping of urine ( "urination  by overflow") in a morphologically normal boy but who may show respiratory signs related to pulmonary hypoplasia (common in severe forms, usually responsible for severe oligoamnios). Urethral valves may also be associated with renal dysplasia or pulmonary hypoplasia.

From a morphological point of view, one distinguishes (Young's classification), according to the  in position with respect to the veru montanum:

-        type I (95 %): submontanal valve:

-        type II: supramontanal valve: remnants of Wolffian ureteral buds.

-        type III: submontanal diaphragm, by defective of resorption of the urogenital membrane

The surgical indication is urgent, from birth, especially if the examination shows a significant impact on the urinary tract: megabladder, megaureters, vesicorenal reflux, bilateral hydronephrosis with thinning of the renal parenchyma.

Two procedures can be proposed initially:

-        transurethral resection of the urethral valves, an endoscopic procedure to be preferred in neonates of 2.5 kg or more; it is performed by electrocoagulation, with a Whitaker hook or the YAG laser

-        bypassing the urethra with a suprapubic catheter (more rarely by surgical vesicostomy), in small children of small weight or when transurethral resection has not been possible or has not given the expected results

-        bilateral cutaneous ureterostomy

Evolution: variable according to the severity of the lesion, the precocity of the management and the importance of the bladder and renal sequelae. Some cases progress to chronic renal failure (represents 10-15 % of kidney transplant indications in France).

Anesthetic implications:

anesthesia of a newborn. Check blood electrolytes and urea/creatinine. Check chest X-ray and SpO2 at room air: pulmonary hypoplasia ? Difficult ventilation in case of pulmonary hypoplasia and ascites. Relatively painless surgery of variable duration but most often brief, not requiring muscle relaxation. Anesthesia can be conducted with a face- or laryngeal mask and associated with a caudal block. If the urinary tract was not drained preoperatively, blood and urine  electrolytes monitoring is necessary postoperatively because the child may present a post-obstruction polyuric syndrome  with the emission of huge amounts of diluted urine.

References :

-        Levin TL, Han B, Little BP.
Congenital anomalies of the male urethra.
Pediatr Radiol 2007; 37:851-62.

-        Eckoldt F, Heling KS, Woderich R, Wolke S.
Posterior urethral valves: prenatal diagnostic signs and outcome.
Urol Int 2004; 73:296-301.

Updated: October 2021