The Association between the Severity and Timing of Antenatal Hydronephrosis Diagnosis and Postnatal Renal Outcomes

Introduction: Antenatal hydronephrosis (ANH) is the single most common congenital malformation and presents in 0.2% of live births. Little is known about the impact of the timing of the diagnosis of ANH on the progression of the hydronephrosis and renal damage over time. Our aim was to determine the association between the severity and timing of ANH and the postnatal renal outcomes.

Material & methods: A single center retrospective study based on medical records of patients referred for prenatal nephro-genetic consultation due to suspected ANH, between the years of 1997-2018. Early ANH was defined as diagnosis

Results: Our study population included 160 patients who were diagnosed with ANH and had a sonographic follow up during the first year of life, 79 (49.3%) were diagnosed with early ANH while 81 (50.7%) were diagnosed with late ANH. The rate of severe ANH was significantly higher in the early ANH group (45.6% vs.19.8%; p<0.001). The severity of ANH was highly correlated with the severity of hydronephrosis at one year of age (Rs=0.569, P<0.001), a stronger correlation was noted in the early ANH group (Rs=0.771, P<0.001). The risk for severe renal outcome at one year of age was higher among the early group with severe ANH compared to those diagnosed later with non-severe ANH (RR 3.33, 66.7% vs 20%, 95%CI 1.45 to 7.15).

Conclusions: Severe ANH is more commonly diagnosed early in the pregnancy. Early diagnosis of ANH is an independent risk factor for poor postpartum renal outcome.