CLINICAL FEATURES AND OUTCOME OF LIVE-BORN NEONATES DIAGNOSED WITH RENAL OLIGOHYDRAMNIOS

Renal oligohydramnios (ROH), caused by severe congenital abnormalities of the kidneys and urinary tracts, has a poor prognosis due to pulmonary hypoplasia and kidney failure. Although the survival rate of neonates with ROH has improved in recent years, information on prognosis remains limited, making it difficult to determine treatment plans and provide prenatal counseling.

This retrospective single-center cohort study included live-born neonates with prenatally detected ROH between 2010 and 2024. The following data were collected from the medical records: maternal age, onset of ROH, presence and duration of anhydramnios, fetal intervention, birth information, primary renal diagnosis, major associated anomalies requiring surgery, overall prognosis, respiratory and kidney outcome. We compared fetal and neonatal parameters between the neonatal survivors and those with neonatal death. Continuous variables were compared using the Mann–Whitney U-test, and categorical variables were compared using the Chi-square test. We also investigated the clinical course of the survivors beyond the neonatal period.

The study included 33 neonates (19 males, 13 females, 1 with ambiguous genitalia). Oligohydramnios developed at a median gestational age of 25 weeks, and 24 (73%) became anhydramniotic at 26 weeks. Primary diseases included bilateral renal agenesis (n=3), bilateral multicystic dysplastic kidneys (MCDK) (n=7), unilateral renal agenesis and contralateral MCDK (n=2), bilateral hypo/dysplastic kidneys (n=3), obstructive uropathy/hydronephrosis (n=10), polycystic kidney disease (n=6) and others (n=2). Fetal intervention was performed in 3 fetuses; 1 underwent serial amnioinfusion to improve the fetal prognosis, 1 underwent vesico-amniotic shunting, and 1 received cystoscopy to relieve the obstruction of the lower urinary tract. The median gestational age at birth was 35 weeks (interquartile range: 32.5–36.5) with a median weight of 2,184 g (1,877–2,675). Of the 33 neonates, 19 died neonatally: 18 due to pulmonary hypoplasia and 1 due to kidney failure. Neonatal survival was significantly associated with later onset of ROH (27.5 vs. 24.0 weeks, p=0.014), shorter duration of anhydramnios (5.1 vs. 8.3 weeks, p=0.001), and higher Apgar scores (score at 1 minute: 4.5 vs. 2.0, p=0.003 and score at 5 minutes: 8.0 vs. 4.0, p=0.001). Two postneonatal deaths occurred at 1.2 months and at 1.4 years following infections. With respect to respiratory support, 20 patients were managed with mechanical ventilation and 10 survived the neonatal period. One of them required home mechanical ventilation, which was discontinued at the age of 4 years. Regarding renal prognosis, kidney replacement therapy (KRT) was initiated in 5 patients in the neonatal period and in 3 patients postneonatally. Among them, 6 survivors received home peritoneal dialysis and 5 patients underwent kidney transplantation. The remaining 6 patients did not require KRT during a median observational period of 8.2 years.

Fourteen out of 33 (42%) live-born neonates who were diagnosed with ROH survived beyond the neonatal period. Later onset of ROH, shorter duration of anhydramnios, and higher Apgar score were associated with neonatal survival. Even in neonates with end-stage kidney disease, long-term survival can be expected if breathing resumes and KRT can be initiated.