Management of Large Renal Calculi (Percutaneous Nephrolithotomy)

Fig. 12.1

Bird’s-eye view of the surgical suit equipment and personnel setup

Two chest rolls are placed longitudinally along the anterior axillary line. The diameter of these rolls should allow for a neutral C-spine positioning, and the breasts are to be placed medially. Placing rolls too medially under the abdomen may cause the colon to be forced posteriorly, potentially increasing the risk of bowel injury during renal access. All pressure points are padded, and pneumatic stockings are maintained for anti-embolic prophylaxis.

Once the patient is positioned, the table is placed in a mild Trendelenburg to keep the patient’s back parallel to the floor, ensuring AP imaging is not distorted. The genitals, perineum, and flank are prepped widely, and percutaneous nephrolithotomy drapes are placed over the flank, with leg drapes covering the split leg extensions. The flank catch pouch is fixed to suction, and a receptacle is placed on the floor under the genitals to catch irrigation.

On the contralateral side of the patient, the fluoroscopy screen is at shoulder level, with the C-arm aligned with the respective flank. The endoscopic tower is aligned with the patient’s thigh and initially directed toward the operator seated to perform the initial cystoscopy. The monitor is adjusted to an ergonomic position to avoid neck strain, in either the sitting or standing position. The camera and light cord are secured to the drape, and typically only one tower provides visualization for the initial cystoscopy, flexible ureteroscopy, and PCNL (see Fig. 12.1). The irrigation stand is placed at the patient’s ipsilateral shoulder, and tubing is fixed to the drape and brought down to the cystoscope. Extra suction tubing is maintained on field for use during ultrasonic lithotripsy .

Step 2: Prone Cystoscopy and Ureteroscopy

A cystoscopy is initially required to survey the bladder, trigonal anatomy, and to place guidewires. Rigid cystoscopy (20 Fr cystoscope, 30° lens) can be used in women, while men require a flexible cystoscopy in the prone position. It is important to clear air from the tubing as this will rise to the trigone in the prone position and obscure the ureteral orifices.

If the patient is pre-stented, a stent grasper is used to deliver the distal curl to the meatus, at which point it may be used to place the initial guidewire. If the initial survey shows significant mucosal edema or inflammation or stent incrustation, a guidewire may be placed alongside the stent prior to removal.

The ureteric orifice will be located superior-lateral when the patient is prone. By starting at the bladder neck 12 o’clock position then sweeping laterally, the ureteric ridge can be followed to the 2 and 8 o’clock positions where the ureteral orifice will generally be encountered. With previous bladder neck or prostate surgery, prolapse, and benign prostatic hypertrophy (BPH), the ureteric orifices may not be in the expected positions. Careful observation for urine jets or the administration of intravenous indigo carmine or methylene blue may help identify the ureteral orifice.

Once the ureteric orifice is identified, a SOLO guidewire is advanced to the level of the kidney using fluoroscopic confirmation. A 10 Fr dual-lumen catheter is then advanced over the guidewire to the proximal ureter to introduce an Amplatz Super Stiff guidewire while providing mild dilation of the ureter. During advancement, one may appreciate a “tight” ureter, which can help in selecting the appropriate ureteric access sheath diameter.

Once both wires are placed, the SOLO wire is maintained as a safety wire and fixed to the drape using a hemostat. The stiff wire becomes the working wire, and it is important to fluoroscopically ensure that the metal wire core extends past the point to which the ureteric access sheath needs to travel.

The size of the sheath selected should be tailored to the patient. Optimal length would place the tip of the sheath in the proximal ureter, without too much excess sheath protruding from the urethral meatus. With proper placement, the maximal amount of ureteral mucosa is protected, and renal drainage of irrigation and stone fragments is achieved. The optimal length of the access sheath can be estimated using the amount of the dual access catheter outside of the patient when the tip is in the proximal ureter during the prior step. Pre-stented ureters can usually accommodate a 13/15 Fr sheath. If the patient was not previously stented, most ureters accommodate 11/13 Fr, though a small number of patients require even smaller sheaths (9.5/11.5 Fr). It is important to be cognizant of the external diameter of your flexible ureteroscope prior to access sheath selection, as not all scopes will fit the smallest diameter access sheaths.

With the working stiff wire in position, the ureteric access sheath is advanced to the proximal ureter. The inner dilator and sheath are assembled, so both are seated properly, and the outer surface is wetted to activate the hydrophilic coating to decrease resistance. Back-loading the sheath over the working wire (with the penis outstretched in men), a change in resistance may be met at the membranous urethra and the ureteric orifice. Fluoroscopy should be used during advancement if resistance is encountered and as the sheath approaches the renal pelvis. If the smallest available sheath will not advance, consider secondary manipulations such as sequential dilation with the inner sheath, balloon dilation, JJ stent insertion, and passive dilation, advancing the ureteroscope over a wire, or an alternative access strategy (fluoroscopy or ultrasound guided).

Once the sheath is placed, the dilator and stiff wire are removed. Flexible ureteroscopy is then performed using intermittent pressure irrigation via a single-action pump. This allows visualization of the relationship of the stone burden to the calyceal anatomy. Stones can be basketed and repositioned prior to gaining percutaneous access, so as to minimize the number of renal access sites and optimize the selection of the access site least likely to be associated with risk of complication or interference from the overlying ribs. Stones can also be lasered to clear a path to an appropriate calyx. On occasions, small stone collections (often appearing as large single stones on imaging) can be removed ureteroscopically, potentially sparing a puncture.

The ureteroscope is manipulated into a posterior calyx to prepare for puncture. Air bubbles can confirm a posterior position. Intermittent fluoroscopy is performed to find a calyx with the straightest trajectory of the scope.

Renal Puncture and Access

Once the appropriate calyx has been selected, the tip of the scope is held steady against the center of the papilla by an assistant. The fluoroscopic image is rotated so that the patient’s spine is at the top of the screen, which allows for more intuitive needle movements in relation to the fluoroscopic image. The C-arm is rotated until the tip of the ureteroscope is seen “end-on,” confirming that the bull’s-eye tract will be in line with the tip of the calyx. With an upper pole puncture, the C-arm is AP for the initial needle manipulation. If the calyx is obscured by an overlying rib, the C-arm can be rotated superiorly or inferiorly to throw the projection of the calculus above or below the rib, respectively, or a different calyx can be selected.

The tip of a Chiba needle is then positioned (using a needle holder) in line with the tip of the scope (under fluoroscopy, on expiration). The shaft of the needle is then manipulated so its trajectory is in line with the C-arm and scope tip forming a bull’s-eye. Once this angle is established, it is maintained, and anesthesia is directed to hold respirations. The needle is advanced through the skin, and the C-arm is rotated toward the radiology technician to get an oblique view to monitor the depth of advancement of the needle as it approaches the tip of the ureteroscope. Once the needle appears to meet the scope on fluoroscopy (Fig. 12.2), anesthesia can resume ventilation, and the assistant inspects the calyx and identifies the tip of the needle endoscopically.