Diagnosis of isolated fetal renal pyelectasis during midtrimester and follow-up the outcome in utero by prenatal ultrasonography

Objective To assess the clinical significance of fetal pyelectasis and its changing in utero. Methods One hundred and ninty-seven isolated pyelectasis cases were retrospective reviewed from Jan 2012 to Jul 2014. Isolated pyelectasis was defined as a renal pelvis anteroposterior diameter (RPAPD) of ≥5 mm without other fetal anomaly in second trimester. Persistent or progressive pyelectasis was defined as a RPAPD of ≥10 mm before delivery. They were divided into two groups according to the size of renal pelvis in second trimester: group A (RPAPD 5-10 mm) and group B (RPAPD ≥10 mm). As the same, there were two groups after 32 weeks of gestation: group C (RPAPD <10 mm) and group D (RPAPD ≥10 mm). Results Totally 154 cases were followed up. There were 188 cases (95.4%) in group A, with 41 cases lost, 141 cases (95.9%) RPAPD <10 mm, 6 cases (4.1%) RPAPD ≥10 mm before delivery. There were 9 cases (4.6%) in group B, with 2 cases lost, remained 7 cases RPAPD ≥10 mm before delivery. Conclusions Although most of the fetuses with RPAPD 5-10 mm in second trimester will remain the same or resolved before delivery, those with RPAPD ≥10 mm may persistent or progress.Prenatal assessment of fetal renal pelvis may provide properly consultation. Key words: Ultrasonography, prenatal; Fetus; Pyelectasis; Pregnancy trimester, second