Clinical Management and Outcomes of Isolated Fetal Pyelectasis Detected at Second-Trimester Ultrasound: A...

Isolated fetal pyelectasis is a common finding on second-trimester ultrasound; however, optimal follow-up strategies remain variable, often leading to inconsistent use of imaging and specialist services. This study aimed to evaluate clinical management pathways and outcomes and to identify factors associated with persistence.

A retrospective cohort study was performed of 221 pregnancies with isolated fetal pyelectasis detected on routine second-trimester ultrasound within a large tertiary healthcare network.

Final outcome data were available in 214 cases. At initial third-trimester follow-up, pyelectasis had resolved in 167/214 cases (74.2%), increasing to 180/214 cases (84.1%) by final antenatal follow-up. Persistence was observed in 34/214 cases (15.9%). Male foetuses demonstrated significantly higher persistence rates than female foetuses (20.4% vs. 7.7%; OR 3.07, 95% CI 1.16-8.12, p = 0.022), while persistent cases had larger median renal pelvic diameters than resolved cases (5.6 mm [IQR 5.0-8.0] vs. 4.7 mm [IQR 4.2-5.3], p = 0.0003).

Isolated fetal pyelectasis demonstrates a high rate of spontaneous resolution, with relatively low persistence on follow-up imaging. These findings support a more risk-based approach to follow-up, with potential to reduce unnecessary imaging and optimise utilisation of specialised fetal diagnostic services.