[Fetal genitourinary anomalies Perinatal and postnatal management with imaging techniques].

Improvements in ultrasound technology and the appropriate timing of antenatal ultrasound has led to refined prenatal diagnosis and enhanced accuracy of diagnosis of fetal renal anomalies and makes it possible to treat obstructive and/or refluxing uropathies before the onset of clinical symptoms. The third trimester renal sonography is the most important to detect hydronephrosis amenable to treatment.Classically, the prenatal diagnosis of hydronephrosis, unilateral renal agenesis, or MDKD initiates postnatal investigations, including sonography, voiding cystourethrography (VCUG), and isotopic renography. The exact degree of renal pelvic dilatation that requires full postnatal investigation is still not entirely resolved. Most authors accept the upper limit of 7 mm for the AP diameter of the renal pelvis. The US examination should be performed after the physiological dehydration period, namely 3-5 days after birth, in an urgent case on the 1st day. A meticulous ultrasound examination performed by a physician who is familiar with the renal abnormalities shows the whole extent of underlying pathology. The role of MR urography in the work-up of renal anomalies, particularly of hydronephrosis, is currently being investigated. Due to the close developmental relationship of the urinary and genital tracts, malformations frequently occur in both of these systems. Therefore in all patients, especially in girls with renal anomalies (unilateral renal agenesis, multicystic dysplastic kidney disease), the internal genitalia need to be evaluated.