LAUSR

Wilms tumor presents with 650 cases annually in the U.S. alone; 5% of these cases present as simultaneous bilateral Wilms tumor while an additional 2e3% present with contralateral metachronous disease.1 Bilateral Wilms tumor (BWT) in particular is associated with an increased risk of long-term renal insufficiency, 10% as compared to 0.7% in unilateral Wilms tumor.1 BWT is also associated with genetic syndromes such as BeckwithWiedemann, Denys-Drash, and Wilms-aniridia-genitourinarymental retardation (WAGR) among others. Standard treatment of BWT is based on NWTS 4 Regimen DD-4 with 12 weeks of neoadjuvant chemotherapy followed by definitive surgical resection; The Children's Oncology Group protocol (AREN 0534) stipulates the importance of obtaining negative margins with lymph node sampling including paraaortic and pericaval nodes.2 Pre-operative imaging is essential for surgical planning, and generally underestimates the extent of healthy parenchyma given compression of neighboring oncologic lesions. Use of intra-operative ultrasound allows more accurate delineation of areas requiring resection, particularly in extensive NSS as in the case below. This report contributes to the body of literature reporting equivalent longterm overall and disease-free survival with NSS compared to unilateral partial nephrectomy with contralateral radical nephrectomy in BWT. Improved long-term negative sequelae