Intraoperative ultrasound in nephron-sparing surgery for paediatric renal tumours: A single-centre cohort study.

BACKGROUND

Nephron-sparing surgery (NSS) for paediatric renal tumours seeks maximal parenchymal preservation. However, incomplete tumour excision often requires additional therapy impacting renal function. We evaluate the impact of intraoperative ultrasound on histological margins during NSS (US-NNS).

METHODS

All patients offered US-NSS (2016-2025) were recorded prospectively and compared to all historical NSS cases (2000-2016) undertaken without ultrasound (non-US-NSS). On-table US was performed by a consultant radiologist using a linear-array transducer on the renal capsule. NSS sought a rim of normal parenchyma and was used for multiple lesions when needed. Data included demographics, histology, surgical margins, and kidney/specimen volumes. Using the formula d1 × d2 × d3 × 0.523, pathological specimen volumes were subtracted from the pre-operative MRI renal unit volumes to determine the percentage of preserved parenchyma. Fisher's exact test compared margin positivity for malignant lesions.

RESULTS

The cohorts comprised 128 non-US-NSS in 51 patients (median age 28 months) and 39 US-NSS in 20 patients (median age 15.5 months). Histology for the 128 non-US-NSS were 64 Wilms tumours (WT), 13 equivocal WT, 51 non-malignant lesions, and for the 39 US-NSS 14 WT, 1 equivocal WT, 3 renal cell carcinoma (RCC), and 21 non-malignant lesions. The median specimen volumes per renal unit was 12.00 cm3 (IQR 4.01-28.5 cm3) vs 8.93 cm3 (IQR 3.34-17.89 cm3), and median preserved parenchyma per renal unit was 84.56% (IQR 62.71%-97.17%) vs 90.74% (IQR 74.20%-96.67%) in non-US-NSS vs US-NSS. Positive margins for malignant lesions occurred in 27/75 (36%) non-US-NSS, and in 0/18 US-NSS (p < 0.001).

CONCLUSION

Intraoperative ultrasound for NSS eliminated positive margins for malignant lesions while maintaining high parenchymal preservation.