The increase of renal pelvis dilatation in the fetus and its significance

Objective: To determine the effects of the changes in fetal renal pelvis dilatation on post-natal diagnosis and outcome. Methods: Prenatal sonographic fetal renal anteroposterior diameters of ≥ 4 mm in the second trimester, which persisted to ≥ 7 mm in the third trimester, were the inclusion criteria. Fifty-six fetuses and 73 renal units with normal karotypes and a solitary sonographic finding of renal pyelectasis, which met the inclusion criteria, were followed, post-natally, until the age of 30 months. The neonates were categorized into three groups, according to their final diagnosis: No hydronephrosis, pelvi-ureteric junction obstruction and hydronephrosis from other causes. The neonates were also categorized according to their outcome: no treatment, follow-up only and surgical treatment. Results: In 17 neonates (30.4%), and 19 renal units, the diagnosis of hydronephrosis was excluded post-natally. In 39 neonates (69.6%), and 54 renal units, an urinary tract pathology was confirmed. The dynamics of pyelectasis in the second and third trimesters of pregnancy differed significantly among the neonates when categorized according to the final diagnosis (P < 0.05), or according to outcome (P < 0.05). Conclusion: It is possible to predict, and distinguish between, long-term conservative and surgical treatments of renal pelvis dilatation in the third trimester of pregnancy.