Subdiaphragmatic extra-lobar sequestrations (ELS) are uncommon entities that are increasingly detected on antenatal imaging. Resection of these lesions has historically been performed, primarily due to the differential of congenital neuroblastoma. There is growing evidence to suggest that these lesions spontaneously involute in early life and that there are sonographic features that enable ELS to be distinguished from more concerning differentials. Our observational cohort study follows such lesions in five patients at Sydney Children’s Hospital. All patients were referred by the MFM unit. Demographic information and relevant imaging characteristics such as size, laterality, identification of a feeding vessel, echogenicity and calcifications were considered. Those with features consistent with ELS and normal catecholamines were reviewed with serial USS’ in the immediate post-natal period and then at 3–6-month intervals. All lesions were detected in the second trimester, 4/5 were left sided and 4/5 had the specific USS finding of a direct feeding vessel. USS surveillance is ongoing for all patients, with a duration ranging from 16 months – 3 years. All lesions have demonstrated a significant decrease in size or else complete spontaneous resolution during surveillance. No patients have proceeded to cross-sectional imaging or operative intervention. Our small cohort demonstrates that antenatally diagnosed subdiaphragmatic ELS’ can be safely observed with USS alone. This avoids the need for cross-sectional imaging and surgical resection. These single-centre, prospective results are promising, but should form the basis of larger trials to make more robust conclusions and management protocols.