Data support expanded role for tubeless percutaneous nephrolithotomy

October 15, 2008

Tubeless percutaneous nephrolithotomy can be performed safely and effectively without preoperative selection, and it appears to be associated with fewer postoperative intracorporeal changes than standard percutaneous nephrolithotomy.

Orlando, FL-Tubeless percutaneous nephrolithotomy (PCNL) can be performed safely and effectively without preoperative selection, and based on a review of findings of postoperative non-contrast computed tomography (NCCT), the tubeless approach appears to be associated with fewer postoperative intracorporeal changes than standard PCNL.

In a presentation at the AUA annual meeting, researchers from the Sourasky Medical Center at Tel Aviv University, Israel, discussed their data on the use of tubeless PCNL in previously operated kidneys.

"Tubeless PCNL is an attempt to avoid the problems accompanying placement of a post-PCNL nephrostomy tube," said Mario Sofer, MD, director of the endourology service at Sourasky. "Initially reported in selective groups of patients, the application of tubeless PCNL was further extended by us to be performed based on intraoperative decision, without preoperative selection.

Outcomes of tubeless PCNL in patients with previous surgery were assessed on the basis of a consecutive series of 145 patients who underwent the tubeless procedure over a 4-year period. The group was comprised of 29 previously operated patients, of whom 14 had undergone nephrolithotomy and 15 had had prior PCNL. The only statistically significant difference between the previously operated and no-prior-surgery groups in analyses of postoperative endpoints was a threefold higher rate of urinary tract infections in the patients with a history of surgery.

Demographic features were similar in the groups of tubeless PCNL patients with and without a history of prior surgery. Comparison of intraoperative characteristics showed that the group with previous surgery was twice as likely to have supracostal access compared with the patients without prior surgery.

"The increased need for supracostal access may suggest that the kidneys become adherent to the flank body wall in an upward position after previous surgery due to scarring and adhesions. In fact, the majority of patients in the previously operated group had fixed kidneys compared with none of the controls," Dr. Sofer noted.

Other features found in the previously operated group that were absent in the controls included the need for fascial incision needle to develop the percutaneous tract (21%) and kidney hypermobility (14%).

No significant differences were reported between the groups with and without a history of surgery with respect to operating room time, postoperative creatinine changes, analgesic requirements, hospital stay, or stone-free rates, although there was a trend in the group with previous surgery for lower immediate and 3-month postoperative stone-free rates.

"It may be more difficult to reach the stone in the pre-operated kidney. However, in interpreting the stone-free data, it is also important to realize that we use strict criteria based on NCCT. In our patients, stone free truly means stone free," Dr. Sofer said.

With patients in the previously operated group stratified by type of surgery, there were no significant differences between the PCNL and nephrolithotomy subgroups with respect to demographic, intraoperative, or postoperative features. There was a trend for a higher rate of kidney fixation in the nephrolithotomy group.

The evaluation of NCCT findings based on type of PCNL included 100 consecutive, prospectively followed patients referred for PCNL. Sixty-five patients underwent a tubeless procedure, while 35 patients suspected intraoperatively to have residual stones were converted to standard PCNL.

NCCT was performed within 18 hours after surgery in all patients. The scans were quantitatively and qualitatively analyzed by two radiologists in consensus who were blinded to the clinical data. Overall, hydronephrosis was the most common NCCT finding, noted in almost three-fourths of patients. Atelectasis and ipsilateral pleural effusion also were recorded in the majority of patients, and other common features (incidence >20%) were gutter fluid, perinephric hematoma, perinephric fluid, ureteronephrosis, renal swelling, and pleural effusion.

The analyses also found that the overall sum of NCCT findings was significantly associated with need for standard PCNL as well as with older patient age, larger stone size, longer hospitalization, and longer operation. The standard PCNL group also had significantly more CT findings present on average than the tubeless group. Considering the individual NCCT findings, gutter fluid and perinephric fluid were present at significantly higher rates in the standard group.

"Patients in our study were not randomized to treatment, and perhaps the patients who underwent standard PCNL had more difficult and more challenging procedures," said Dr. Sofer. "However, comprehensive statistical analysis revealed baseline and stone feature data were similar in the two groups, as were the technical complexity, operative times, postoperative clinical outcomes, and complications. Therefore, we believe our assumptions in comparing the standard and tubeless PCNL groups are justified."