Very rare. It is part of the causes of LUTO (acronym for Lower Urinary Tract Obstruction). It could be the result of an imbalance in tissue growth during the development of the urethra, incomplete hypospadias, incomplete urethral duplication or a defective union between the glandular and urethral tissues.

It is found either in the bulbar urethra (40 % of cases), at the penoscrotal junction (30 % of cases), or in the penile urethra (30 % of cases).  Sometimes associated with a urethral diverticulum. Clinical signs are highly variable and can occur before birth in the form of hydronephrosis or distended bladder, or between birth and adolescence in the form of urinary tract infections or a weak urine stream. Other clinical manifestations are obstruction of the lower urinary tract, a distended bladder on palpation, urinary incontinence, renal failure, renal dysplasia, trabeculation and thickening of the bladder and vesicoureteral reflux. After valve removal, more than 20 % of patients experience abnormalities in renal function, which can evolve to end-stage renal failure. Urethral stenosis or a damaged external vesical sphincter are among the complications of surgery.

Diagnosis: cystourethrogram during miction (CUM), typically showing dilation of the urethral upstream of the valve and its narrowing downstream. Trabeculation of the bladder, a bladder or urethral diverticulum may also be observed. At echography, patients may present bladder distension and bilateral ureterohydronephrosis.

Prenatal diagnosis: prenatal ultrasound may show hydronephrosis, distended bladder or a periurethral cystic mass, a sign of the malformation.

Treatment:

• initial management: decompression and drainage of the genitourinary system using an indwelling urethral or suprapubic catheter or ureterostomy
• surgical treatment: transurethral removal of the valve, either by laser, electrocautery or cold blade urethrotomy. However, this solution can be postponed in favor of a primary vesicostomy in preterm infants, or low birth weight infants with high serum creatinine.
• in case of diverticulum of the urethra, invasive urethral reconstruction is necessary, with excision of the diverticulum and tubularization of the urethra.

Prognosis: In general, valve removal gives good functional results, although there is a risk of complications and chronic renal or bladder dysfunction.

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 have a post-obstruction polyuric syndrome with the emission of huge amounts of diluted urine.

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Updated: October 2021