[Factors associated with the survival of fetuses with a prenatal diagnosis of megabladder].

The presence of fetal megacystis in a renal ultrasound may suggest a mechanical or functional bladder outlet obstruction, an uncommon condition with a poor outcome. To determine prog nostic factors in fetuses with prenatal diagnosis of megacystis. Retrospective study carried out between 2003 and 2018 in the Orient Perinatal Reference Center (CERPO), Uni versity of Chile. Prenatal and postnatal data were analyzed, as well as etiology, pulmonary hypoplasia, medical and surgical treatment, mortality, renal function, and need for renal replacement therapy. The primary variable analyzed was survival at one year, and the secondary ones were renal function and predictors of survival. Statistical analysis was performed using the Mann-Whitney U tests or Fisher test, and a p < 0.05 was considered statistically significant. Twenty-five fetuses with prenatal diagnosis of megacystis were included. 52% of them presented oligohydramnios and 84% showed renal anomalies. Vesicocentesis was performed in 15 fetuses and vesicoamniotic shunt was performed in 5 cases. There were 6 intrauterine fetal deaths (24%) and, among the 19 live births, 9 died soon after birth (36%) and 1 died in the post-neonatal period due to a non-nephron-urological cause. Nine newborns survived by one year of age (36%), seven of them with associated nephron- urological anomaly, and two were healthy patients. Two patients developed chronic kidney disease. The presence of pulmonary hypoplasia was the only factor associated with increased perinatal mor tality (p<0.05) secondary to oligohydramnios in all cases. Oligohydramnios was not identified as a prognostic factor in this study. The prenatal diagnosis of megacystis comprises a wide spectrum of pathologies including conditions with a high perinatal mortality rate to healthy fetuses with transient enlarged bladder without nephron-urological pathology. The only factor associated with increased perinatal mortality was pulmonary hypoplasia.