Two techniques help improve results of PCNL

March 1, 2005

Mumbai, India—Two newer techniques offer potential to improve the experience for patients undergoing percutaneous nephrolithotomy, according to separate presentations made at the World Congress on Endourology. One study focused on using a plastic model for visualization purposes before operating on complex renal stones, and the other examined the effectiveness of a hemostatic gelatin matrix to seal the percutaneous nephrostomy tract.

Mumbai, India- Two newer techniques offer potential to improve the experience for patients undergoing percutaneous nephrolithotomy, according to separate presentations made at the World Congress on Endourology. One study focused on using a plastic model for visualization purposes before operating on complex renal stones, and the other examined the effectiveness of a hemostatic gelatin matrix to seal the percutaneous nephrostomy tract.

Having a 3-D plastic model of the pelvocalyceal system is helpful for visualization purposes when operating on complex renal stones, reported researchers from Uppsala University, Uppsala, Sweden. The model proved to be better for planning purposes of percutaneous nephrolithotomy than intravenous pyelogram and CT with contrast, said Eva Radecka, MD, an Uppsala University radiologist who presented the goup's preliminary findings on this concept.

An exact plastic copy of the pelvocalyceal system (stereolithographic model) is the product of processed computer data generating a virtual replica of pelvocalyceal system with the stone.

Dr. Radecka pointed out that the results were based on subjective rather than objective data from the urologists. The urologists found biomodels useful in morphologic assessment, planning and rehearsal of surgery, and for informed consent from patients. Dr. Radecka said that the limitations of the technology are manufacturing cost and time. It takes 2 days to make the model, and it costs approximately $1,400.

Sealing method lessens pain In the second study, patients who received a hemostatic gelatin matrix (FloSeal, Baxter, Deerfield, IL) to seal the percutaneous nephrostomy tract did not experience the postoperative pain that is associated with a percutaneous tube. The method of using the matrix was presented by Isaac Kim, MD, an endourology fellow at the University of California, Irvine, working with Ralph Clayman, MD, and colleagues.

The retrospective study examined outcomes in 10 patients who had hemostatic gelatin matrix to seal the percutaneous nephrostomy tract and 10 patients who had standard PCNL with a 10F nephrostomy tract. As the postoperative pain is mainly associated with a percutaneous tube, the authors developed an innovative method of sealing the tract with hemostatic gelatin matrix and encouraging antegrade drainage of urine by a double-J stent, thereby avoiding the placement of a nephrostomy tube.

After removing the stone, if the patient is endoscopically and radiologically stone-free, then an occlusion balloon catheter is passed retrograde over a guidewire into the collecting system and the balloon is inflated at the entry point into the collecting system. Hemostatic gelatin matrix is instilled into the tract while simultaneously removing the Amplatz sheath. An indwelling 7F double-J stent and a Foley catheter are placed. The skin is then closed with 2-octyl cyanoacrylate (Dermabond, Ethicon, Somerville, NJ).

"There were no significant problems with patients who underwent a tubeless PCNL," Dr. Kim said. "We suspect that the use of FloSeal is a safe way to contain bleeding after a standard PCNL."

The researchers noted that mean operative time was shorter in the hemostatic gelatin matrix group (173 min vs. 271 min for the standard PCNL group, p=.05), and the mean hospital stay was shorter (43 vs. 51 hr, p=.50). They found no statistically significant difference between the two groups in estimated blood loss, postoperative analog pain scales, amount of analgesic use, and stone clearance rates.

The researchers concluded that hemostatic gelatin matrix serves to achieve hemostasis of the nephrostomy tract, precluding the need for nephrostomy tube or a sutured closure. They are in the process of conducting a prospective randomized trial with a large number of patients.