Fetal renal anomalies : diagnosis, management, and outcome

In two to three percent of fetuses structural anomalies can be found with prenatal ultrasound investigation. Anomalies of the urinary tract account for 15 to 20% of these anomalies with a detection rate of approximately of 90%. In Chapter 2, 3 and 4 we present reference curves for size and growth of fetal kidney, renal pelvis and adrenal gland, preceded by an intra- and interobserver variation analysis. In Chapter 5 we describe the ultrasound findings and outcome of a large cohort of 402 fetuses with a prenatally diagnosed urinary tract anomaly. Of the fetuses died 26,4% before or after birth directly related to the renal tract anomaly. The overall conclusion for obstructive uropathy that can be drawn from this series is that, regardless of the presence of 1 or 2 kidneys and regardless of the degree of urinary tract dilatation, the prognosis for renal function is excellent when oligohydramnios is absent before birth and when proper urological care is given postnatally. In Chapter 6 a large cohort of 100 fetuses with unilateral multicystic kidney disease, prenatally diagnosed, is described. Children with unilateral MCKD have 75% chance of having other congenital anomalies of the urinary tract and therefore they need to be precisely screened pre- and postnatally. We recommend that a routine postnatal examination consist of an ultrasound examination, an isotope scan and a VCUG and when a nephrectomy is done also a cystoscopy and a colposcopy to detect possibly hidden anomalies of the genitourinary tract. In Chapter 7 a study is described that was done to investigate urinary tract morbidity in late childhood in infants with a prenatally diagnosed mild pyelectasis. Based on these findings we advocate in case of a mild renal pyelectasis at about 20 weeks of gestation a single follow-up scan in the third trimester. The child should only be referred for postnatal examination if there is progression of the pyelectasis to >10mm. With this policy there seems to be only a very low chance of missing an occasional case of VUR or potential obstruction. Parents should be advised to visit the general practitioner in case their child is lethargic or has fever of unknown origin to have the child's urine tested to rule out urinary tract infection in order to prevent renal damage. In Chapter 8 a study is described on the variation of the dimensions of the fetal renal pelvis in relation to the degree of bladder filling in fetuses with mild pyelectasis. In one third of the fetuses the dilatation of the renal pelvis varied according to bladder volume with a mean difference of 6,7 mm and a largest observed difference of 14,3 mm. So the filling state of the bladder should be taken into account when fetal hydronephrosis is suspected. CONCLUSION The mortality rate in fetuses is high once a renal anomaly is identified. The prognosis for the surviving children is relatively good and these infants have only a little chance on lifelong damage, if during pregnancy the right diagnosis has been made and if these children have had good urological care after birth. It is important that paediatricians and urologists are acquainted with the advices, which were given when antenatally anomalies at the urinary tract are diagnosed, because they will be consulted often about these anomalies after birth