The shape of the kidney pelvis in the fetus with hydronephrosis grade III as a predictor of surgical treatment in postnatal period

BACKGROUND: Fetal hydronephrosis is one of the most common malformations of the urinary system. The main goal of prenatal diagnostics is to identify a risk group with a dilatation of the renal collecting system due to mechanical obstruction of the pelvic-ureteral segment. AIM: The aim of the study is to definition of a prenatal risk group with a high probability of early surgical intervention in the postnatal period based on an assessment of the predictor properties of the pelvis shape in hydronephrosis grade III. MATERIALS AND METHODS: A prospective analysis of the results of prenatal ultrasound examination of 77 fetuses (82 renal units) with grade III hydronephrosis (SFU classification) was carried out. The anteroposterior diameter of the pelvis was measured in millimeters at the level of the kidney gate. With the ellipsoid shape of the pelvis, the compression ratio of the ellipse was calculated as the ratio of the small semi-axis of the ellipse to its large semi-axis. All parameters were recorded in the third trimester of pregnancy. The study included cases of hydronephrosis with parenchymal thickness not differing by more than two sigma deviations from the standard value. The first ultrasound examination in the postnatal period was performed during the first month of life and then at 3, 6 and 12 months. RESULTS: Prenatally, 57 kidneys had an elliptical pelvis and 25 funnel-shaped. The anteroposterior diameter of ellipsoid (16.5 [13; 20]) and funnel-shaped pelvis (15.0 [13; 17.8]) did not differ statistically significantly (p = 0.39). 36 (43.9%) patients were operated on, 29 of them were operated at the age of 13 months, due to the increase in APD from 17.56.0 to 27.98.2 (p = 0.001) and the transition of hydronephrosis to the IV degree by 1 month of life. The remaining 7 children had gradual progression of hydronephrosis and were operated at the age of 12 months and older. In 56.1%, resolution, regression or stabilization of hydronephrosis were noted during dynamic observation lasting 1 year. With a single-variant analysis, it was found that the configuration of the pelvis and the compression ratio of the ellipse statistically significantly correctly predicted the progression of hydronephrosis and the probability of surgery at 69.5% and 80.5%, respectively. At the same time, the compression ratio had a higher sensitivity and specificity. CONCLUSIONS: Fetal hydronephrosis with a funnel-shaped configuration of the pelvis, has a functional nature and regresses after birth during the first year of life. The antenatal ellipsoid configuration of the pelvis, approaching the circumference, is a statistically significant predictor of surgical intervention due to the progression of hydronephrosis due to external causes of obstruction.