Contrast-enhanced and conventional ultrasound images of renal wounds after partial nephrectomy

Objectives: To observe the features of conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) images of renal wounds after minimally-invasive partial nephrectomy (MIPN) and evaluate their severity using these two modalities. Methods: This prospective, observational study included 120 patients who underwent MIPN from April to December 2019 in our hospital. The postoperative US images were evaluated and classified, and contrast extravasation characteristics of CEUS were recorded. The correlation between the classification system and perioperative factors was analyzed.Results: Eighty-five patients underwent US and CEUS after MIPN. Conventional US images were classified into three grades according to the surface morphology of renal wounds and overall shape of the kidney around the incision. Univariable and multivariable analyses indicated that the N component of the R.E.N.A.L. score and the resection range were preoperative and intraoperative factors, respectively, related to the US image grades (UIGs). A deep location and expanded excision contributed to an increased UIG. The extravasation rate increased with the UIG (Spearman correlation rho=0.247, P=0.022), and a higher UIG prolonged the length of extravasation. The depth of the tumor and resection range were related to the UIG.Conclusions: US and CEUS were feasible and repeatable methods that reflect the morphologic changes of renal wounds after MIPN and may be useful for evaluating their severity.