Prevalence is unknown, but it affects boys more than girls. The cause is unknown. It is part of the causes of LUTO (acronym for Lower Urinary Tract Obstruction). At prenatal echography, a megabladder, oligohydramnios or anhydramnios and sometimes urinary ascites (that can be life-threatening for the fetus) can be observed. When the fetus survives until birth, respiratory failure due to pulmonary hypoplasia (Potter sequence), megaureter, hydronephrosis and enlarged dysplastic often cystic kidneys, with functional or non-functional failures, as well as abdominal distension, may be present. Some patients may have an urachal fistula or a vesicocutaneous or vesicorectal fistula that has decompressed the bladder in utero.

Prenatal diagnosis is based on echography. After birth, mictional cystography and/or cystoscopy may be performed to make the final diagnosis and distinguish between urethral atresia and other causes of megabladder.

Differential diagnosis(es): posterior urethral valve, anterior urethral valve, urethral stenosis, urethral agenesis, urethral duplication, cloacal malformation and megabladder-megaureter syndrome. Urethral atresia can be associated with several other diseases, including caudal dysplasia, cloacal exstrophy, DiGeorge syndrome, Prune Belly syndrome, cryptophthalmia in the context of Fraser syndrome, Johnson-Munson syndrome, Meckel-Gruber syndrome, trisomy 18, silenomelia and Townes-Brocks syndrome.

Prognosis: prenatal decompression (vesicoamniotic shunt) allows survival and may even provide normal bladder and kidney function. Evolution to renal failure is common.

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 hypolasia and ascites. Relatively painless surgery of variable duration but most often quite brief, not requiring muscle relaxation. Anesthesia can be managed 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.

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Updated: October 2021