Abstract：Objective To assess the clinical significance of isolated fetal renal pyelectasis and its changes
in utero. Methods One hundred and fourteen isolated pyelectasis cases with their RPAPD (Renal
Pelvis Anteroposterior Diameter) ≥ 4 mm without other fetal anomaly who were screened from 13500
pregnant women by using ultrasound were retrospectively reviewed. Results There was no obvious
difference between RPAPD and the age of pregnancy (P=0.062)>0.05; 72 cases (63.15%) were one sided
renal pyelectasis, more than 42 cases (36.84%) of renal pyelectasis were on both sides; 69 cases (66.35%)
were one sided renal pyelectasis and RPAPD < 10 mm before delivery, more than 35 cases (33.65%) with
bilateral renal pyelectasis and RPAPD < 10 mm; 3 cases with RPAPD ≥ 10 mm (30%) and one sided
renal pyelectasis were treated with continuous renal pelvis separation, less than 7 cases with RPAPD
≥ 10 mm (70%) and bilateral renal pyelectasis; According to the Chi-square test between two groups
(RPAPD < 10mm Before Gelivery Group and RPAPD ≥ 10 mm Continuous Renal Pelvis Separation
Group), the difference was statistically significant (P=0.0023<0.05). Conclusion Although most of the
fetuses with RPAPD ranging from 4 to 10 mm in second trimester would remain the same or resolved
before delivery, those with RPAPD ≥ 10 mm might continuously expand. Tracking and monitoring of
fetal renal pelvis by using ultrasound could provide proper prenatal consultation.
