Fetal Urinoma Secondary to Posterior Urethral Valve and Its Association to Postnatal Renal Function: A Multicenter Retrospective Study.

Aim: The role of prenatal urinoma in lower urinary tract obstruction (LUTO) such as posterior urethral valves (PUV) is debated. We aimed to describe the risk factors associated with fetal urinoma and the association between fetal urinoma and postnatal renal function before 2 years of age.

Methods: This retrospective multicenter case-control study from 2000 to 2018 included pregnant patients with suspected LUTO in their male fetus on prenatal ultrasound and postnatal confirmation of PUV. The exposure criterion was prenatal urinoma. The main composit outcome (MCO) was chronic kidney disease stage 3 or higher (CKD3+) before 2 years or death. Descriptive analyses of patient data and crude and multivariate logistic regression analyses were performed in an intent-to-treat fashion, thus including lost-to-follow-up patients. Ethical approval # 20.144.

Results: We included 299 patients, of whom 39 (13%) had prenatal urinoma. Thirty-eight patients had a termination of pregnancy (12.7%). Sixty-four (24.5%) patients'children were MCO positive. Twenty-one children were lost-to-follow-up, including one prenatal urinoma. Thirty-nine (60.9%) of the remaining children had CKD3+ before the age of two, of whom 6 had a prenatal urinoma (9.4%). Among the 197 children negative to the MCO, 24 had a prenatal urinoma (12.2%, p = 0.42). Four died neonatally. In livebirth patients, prenatal urinoma was associated with obstetrical complications (p = 0.02), prenatal bloodcord sample for fetal beta2-microglobulin (p = 0.01) and uro-amniotic shunt (p = 0.01). Patients with prenatal urinoma more often presented with oligohydramnios (p = 0.01) and dilated posterior urethra (p = 0.01) and were less likely to have urinary tract infections (p = 0.02), although their DMSA scan was more often altered (p = 0.001). Prenatal urinoma was not significantly associated with CKD3+ before 2 years (OR = 0.56, CI98% = 0.20-1.39, p = 0.23).

Conclusion: Renal function in infants with PUV was not worsened by the presence of a prenatal urinoma. Thus, there should not be any more pejorative message conveyed to concerned couples apart from other already known prenatal poor prognosis risk factors.