Ureteroscopic Management of Renal Calculi

Improvements in technology have expanded the indications for the ureteroscopic management of renal calculi. Flexible ureter-renoscopes have become smaller and more flexible and have improved optics compared with prior generations. They allow access to the entire collecting system. Instrumentation, such as flexible baskets, ureteral access sheaths, and smaller holmium laser fibers, have facilitated the treatment of renal stones. Retrograde intrarenal surgery is effective for treating stones in any location in the kidney and even for stones larger than 1.5 cm, although repeat procedures may be necessary.

Preoperative Planning and Considerations

Patients should have an appropriate preoperative evaluation, including urinalysis and urine culture and appropriate imaging studies. It is helpful to have a preoperative computed tomography (CT) scan to delineate stone size and location before surgery. This aids in preoperative planning and provides better patient counseling on expectations such as the likelihood of being stone free and the potential for staged procedures. All patients should have a preoperative urinalysis and urine culture performed, and any untreated infections should be treated with a course of culture-specific antibiotics. Patients can remain on their anticoagulants, including aspirin, clopidogrel, or warfarin, for ureteroscopy. It is the author’s practice to have patients continue these medications because it has been shown to be safe to do so.

Patients should be counseled regarding the need for a ureteral stent and the expected duration for the stent. It is important to counsel patients regarding the need for repeat procedures, in particular if the ureteroscope is unable to be advanced into the kidney to treat the stone. In such a case, a ureteral stent should be left in place, and a second staged procedure should be planned in 10 to 14 days.

An appropriate preoperative evaluation with anesthesia should be performed as is routine for the specific institution. General anesthesia with neuromuscular paralysis is preferred for renal endoscopy, and this should be communicated with the anesthesiologist. This significantly reduces respiratory variation associated with spontaneous breathing and allows the anesthetist to hold respirations for stone fragmentation.

Operative Technique

Patients are positioned in the dorsal lithotomy position. The procedure is begun by inserting a rigid cystoscope into the bladder. The ureteral orifice is identified and cannulated with a 5-Fr open-ended ureteral catheter. A retrograde pyelogram is performed under direct fluoroscopic guidance using half-strength water-soluble contrast. The pyelogram provides an anatomic “roadmap” for inspection of the collecting system. A guidewire is advanced through the ureteral catheter and up into the renal pelvis ( Fig. 42.1 ). A second “safety” guidewire is advanced alongside the wire into the renal pelvis under fluoroscopic guidance. The ureteral catheter and cystoscope are then removed over the guidewires, leaving them in place.


Fluoroscopic image of safety guidewire into the intrarenal collecting system.

It is the author’s preference to use a ureteral access sheath for ureteroscopic treatment of renal calculi. The size of ureteral access chosen depends on the size of the ureteroscope to be used. In general, the author prefers a 12- ×14-Fr access sheath. Alternatively, an 11- × 13-Fr ureteral access sheath can be used with smaller flexible ureteroscopes. The ureteral access sheath and obturator are then placed over the guidewire up to the proximal ureter, just distal to the ureteropelvic junction (UPJ). The use of the access sheath facilitates passage of the flexible ureteroscope for removal of stones and has been shown to decrease intrarenal pressures and ultimately lead to greater stone-free rates. If the ureteral orifice is noted to be narrow or stenotic, then the obturator may be passed initially by itself over the guidewire to gently dilate the lower ureter. The ureteral orifice can also be visually dilated using a semirigid ureteroscope, which can be advanced between the wires under direct vision. When this is unsuccessful, sequential ureteral dilators or a pressure-regulated ureteral dilating balloon may be used. When the ureteral access sheath is in appropriate position, the obturator is removed. In cases when, despite these maneuvers, the ureteral access sheath cannot be placed, the flexible ureteroscope can be advanced over one of the guidewires under fluoroscopic image guidance and into the kidney.

A flexible ureteroscope with a pressurized water source is used for renal endoscopy. The ureteroscope is advanced through the ureteral access sheath, and the ureter is inspected in a retrograde fashion. The UPJ is then traversed gently, and the renal collecting system is entered. The calyces of the kidney are then systematically inspected ( Fig. 42.2 ). Modern-generation flexible ureteroscopes allow for complete inspection of the collecting system, including the lower pole calyces. A retrograde pyelogram may be performed through the ureteroscope at this point in case further delineation of the intrarenal anatomy is required.

Jan 2, 2020 | Posted by in UROLOGY | Comments Off on Ureteroscopic Management of Renal Calculi

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