P10.03: Magnetic resonance imaging as an alternative to amnioinfusion in suspected fetal renal agenesis

Primary renal agenesis is not a diagnostical challenge as oligohydramnios is almost always present at the time of the anomaly scan. In contrast secondary (or progressive) renal agenesis (e.g. in multicystic dysplastic kidney) is frequently missed as kidneys are present but smaller in size and they tend to vanish with advancing gestational age. We present a case of a 24-year-old woman, gravida 1 para 0, referred to our center at 24 + 3 weeks' gestation for suspicion of IUGR and oligohydramnios. Ultrasound showed a small multicystic left kidney. The right kidney could not be visualized. In view of the challenging scan conditions and the fact that normal kidneys were documented on previous exams a fetal MRI was requested. This case stresses the possibility of MCDK and other forms of cystic renal dysplasia in fetuses with oligohydramnios—even if a normal urinary tract was visualized on earlier exams. From our experience MRI as an alternative to amnioninfusion was decisive in confirming the diagnosis.