Intraoperative Localization of Renal Calculi

Abstract

With the success of extracorporeal shock-wave lithotripsy and the percutaneous techniques of stone removal, conventional stone surgery will be reserved for the more complex cases. In order to reduce the recurrence rate, it is essential that all free calculi be removed at the time of surgery. The authors would suggest careful preoperative evaluation of stones with intravenous urography, tomography, and appropriate oblique and lateral views to determine size, number, and location of all calculi. Retrograde studies with a combination of contrast and CO2 can further define caliceal arrangement and identify obstructed calices or narrowed infundibuli that may require surgical repair. At the time of surgery, complete renal mobilization will facilitate all localization techniques. Elevation of the kidney with cotton tapes allows proper alignment of the x-ray beam and target (kidney and film). If extensive scar tissue or perinephric inflammation prevents adequate mobilization, the more maneuverable dental x-ray unit or ultrasonography will assist in localization of stones. A preliminary film will often provide considerably greater detail than even preoperative tomography. The surgeon needs to select the appropriate film type and exposure technique. Small stones (less than 2 mm) or poorly opacified stones may require use of a film that incorporates an intensification screen for improved resolution and contrast. Multiple small caliceal stones are best managed with careful needle localization prior to pyelotomy or nephrotomy. Anteroposterior and 90-degree views can give effective three-dimensional localization. If there remains any question or if localization is difficult because stones are poorly opaque or nonopaque, ultrasonography is useful to localize peripherally situated stones quickly and is best initiated prior to introducing air into the collecting system. To facilitate the speed of additional intraoperative films, especially once the vessels are clamped, Polaroid film has been shown to give good-quality resolution with reduced development time. At the conclusion of each case, we would suggest nephroscopic inspection of each calix to identify tiny residual fragments that might be missed on the final operative film. With direct visualization, these stones can be grasped effectively or irrigated out. A potential disadvantage to the use of any type of intraoperative localization technique is the possibility that an overly zealous attempt to remove tiny particles will cause unnecessary damage to the kidney. Small particles may pass spontaneously, and their presence is not always incompatible with achieving sterile urine and stable renal function.(ABSTRACT TRUNCATED AT 400 WORDS)