Percutaneous Nephrolithotomy (PCNL)
Percutaneous nephrolithotomy (PCNL) is an elegant form of minimally invasive surgery for larger stones in the kidney or upper ureter, or for stones that are not good candidates for shock wave lithotripsy (SWL).
Hospitalization for PCNL is anywhere from one to five days, depending on complexity. In this technique, a surgeon places a telescope directly into the kidney through a small tract about the size of a pencil. The tract is usually placed below the tip of the lowest rib. This operation requires a general anesthetic and the patient is positioned face down or prone on a well padded operating table. A telescope is placed into the bladder and a small catheter tube is passed up the ureter of the involved side.
The surgeon places a second catheter in the bladder to drain urine. The ureteral catheter is used during the operation to inject contrast fluid into the interior urine space of the kidney where the stone is located in order to visualize it well using fluoroscopic or x-ray imaging. The tract into the kidney is then established and a special telescope is inserted into the kidney.
Very large kidney stones and staghorn stones (large stones filling the internal branches of the kidney) are pulverized with a variety of instruments including ultrasound, pneumatic hammers, and lasers. Small fragments may be vacuumed out and larger fragments the size of peanuts (10mm) may be removed intact.
A surgeon may insert flexible telescopes to inspect the internal branches of the kidney and meticulously remove stones. For some stones with a complex shape, more than one tract may be necessary to eliminate all stone material.
The goal of the surgery is the complete removal of all stones, expecially for stones related to infections, as bacteria inhabit the interior of the stone and cause stone crystals to form and grow. In order to avoid recurrent infection in these cases, all stone debris, including the bacteria, must be eradicated.
Upon completion of the operation, the surgeon places a temporary tube into the kidney through the established tract and sutures it to the skin for security. The ureteral catheter is removed and the bladder catheter is left in place. The patient is awakened from the anesthesia and transported to the recovery room where monitoring takes place for about an hour. Following this the patient is transferred to an inpatient floor.
This operation usually requires pain medication for comfort and a special intravenous (IV) pump for delivering pain medicine if needed. The patient is on bed rest for the rest of the day and overnight. You may take clear liquids, but we usually discourage regular foods until the following day.
Special pneumatic compression pumps are placed on the legs while at bed rest to avoid a possible blood clot. Urine drainage from the catheters is typically rose or cranberry in color.
The following morning the patient may have x-rays to determine if any stone material remains. Usually the bladder catheter is removed at that time if there are no problems. If there are no stones, no leakage within the kidney noted, and no blockage in the ureter by stone fragments or blood clots, the tube in the kidney is removed either the same day or the following day. The patient is then ready for discharge.
Taking a second look
If there is residual stone material, the urologist usually waits at least another day and performs a second look into the kidney to remove the remaining stones. Usually there is some stone material not visible at the original operation. This second-look operation may be performed with general anesthesia if it appears that substantial manipulation will be necessary, or with IV sedation alone if there is minimal residual stone remaining.
This procedure is usually brief, less than one hour. The patient is sent to the recovery room again for monitoring and then back to the inpatient floor.
A nephrostomy tube may be removed if there is no remaining stone and no other problems. Otherwise the tube may be kept for one or more days until the urologist decides it is safe to remove it. The patient may be discharged with the tube temporarily in place, draining urine into a leg bag. Then the patient returns to the doctor’s office in a few days for removal, an essentially painless procedure that takes only a few seconds.
Laboratory analysis of extracted stones is available about three or four weeks after surgery. For large stones, residual stone may persist after one or more percutaneous procedures. A urologist may recommend lithotripsy to better clear all remaining fragments that are too difficult or inaccessible by percutaneous techniques. Occasionally, irrigation of residual debris through one or more nephrostomy tubes is recommended to flush out and dissolve the remnants, depending on the composition of the stone.
Risks of PCNL
Potential complications of PCNL are less than for open surgery but generally more than for ureteroscopic stone removal or lithotripsy. Bleeding requiring a blood transfusion is necessary in about 2 percent of cases. The risk of transfusion is increased for a larger, more complex stone, or if multiple tracts are required.
The potential for infection requiring IV antibiotic treatment is greater about 5% with a possibility for severe life threatening infection of less than 1 percent. There is a small risk (less than 1 percent of cases) of injury to other organs near the kidney, such as the bowel, spleen, or liver.
Internal leakage of urine is an uncommon occurrence that may prolong hospitalization until adequate drainage is performed. Injury to the space about the lung (pleura) is rare but may occur if a tract over a rib is necessary for a stone in the upper kidney. A collapsed lung or fluid collection around the lung may occur, requiring a tube for a few days to repair this problem.
Stone free results for large simple stones is about 95 percent at one procedure, and about 90 percent for complex staghorn stones requiring one or more procedures. Follow-up for PCNL is usually an abdominal radiograph (KUB), renal ultrasound, and blood tests in two weeks.
An intravenous pyelogram (IVP) may be ordered in six weeks to evaluate the anatomy and function of the kidney. The patient should make follow-up appointments with the urologist at six and twelve months to monitor for stone recurrence, and then annually. For infectious stones, urine cultures should be performed every three months for the first year.
If you have symptoms of kidney stones, contact us to schedule an appointment with our board certified urologists in San Francisco East Bay Area to determine the optimal treatment option for you.