Anatomical background for nephron-sparing surgery in renal cell carcinoma.

3-Dimensional endocasts of intrarenal structures were analyzed on the basis of their importance for performing nephron-sparing surgery. In 86.6% of the endocasts the superior pole was related to 3 arteries involved in its resection. Management of the superior (apical) segmental artery as well as ligature of the artery related to the anterior surface of the upper infundibulum are generally not difficult. Ligature of the posterior segmental artery branch related to the superior pole is critical due to the risk of injuring this segmental artery and loss of a great portion of renal parenchyma. In 62.2% of the endocasts the inferior pole resection involved ligature of the inferior segmental artery with no risk to the posterior segmental artery. A deep anatomical knowledge is mandatory to perform mid kidney resection. In 36.4% of the endocasts this region received subdivision branches of arteries from superior and inferior poles, and in 62.2% the mid kidney resection involved amputation of calices that are dependent on polar calices. The middle branch of the posterior segmental artery also is involved in mid kidney resection and its ligature demands much care to avoid injury to the posterior segmental artery itself. In the dorsal kidney the posterior segmental artery is involved and must be safeguarded in all cases of either superior pole or mid kidney resection. In 37.8% of the cases the posterior segmental artery also may be involved in inferior pole resection. When present (69.2%), the retropelvic vein must be previously ligated to provide safe management of the posterior segmental artery.