Two timely topics are investigated: the sensitivity and cost-effectiveness of unenhanced CT to detect residual calculi following percutaneous nephrostolithotomy and the use of percutaneous endoscopic resection for patients with transitional cell carcinoma (TCC).
Unenhanced Computerized Axial Tomography to Detect Retained Calculi After Percutaneous Ultrasonic Lithotripsy
Waldmann TB, Lashley DB, Fuchs EF.
J Urol. 1999;162:312–314.
Unenhanced CT scanning (including helical CT) was the sole method of identifying residual fragments in 121 patients (124 kidneys) after percutaneous ultrasonic lithotripsy. Patients were classified based on their CT findings as having:
No retained calculi.
Insignificant (1 to 3 mm) retained calculi.
Retained calculi requiring shock wave lithotripsy (SWL).
A requirement for second-look nephroscopy.
On CT scan, 73 kidneys (59%) were found to be free of stones, and insignificant fragments were seen in 21 kidneys (17%). Follow-up of the patients with “insignificant calculi” was not available. SWL was used to manage residual fragments in 8 kidneys (6%), and a second percutaneous procedure was necessary in 23 kidneys (19%). Although the investigators did not directly compare these patients with others for whom different modalities (plain renal tomography or second-look nephroscopy) were used to detect residual calculi, they comment that compared with their earlier experience with renal tomography, CT scans offer several advantages. CT scans permit visualization of radiolucent calculi, have less interference from the nephrostomy tube, and can determine the precise 3- dimensional position of residual calculi, which can significantly facilitate endoscopic removal when necessary. Compared with second-look nephroscopy, CT scans are less expensive, less invasive, and probably more likely to detect residual stones that were not seen during the original nephroscopy. The investigators recommend unenhanced CT as the primary method for evaluating patients after percutaneous ultrasonic lithotripsy.
Sensitivity of Noncontrast Helical Computerized Tomography and Plain Film Radiography Compared to Flexible Nephroscopy for Detecting Residual Fragments After Percutaneous Nephrostolithotomy
Pearle MS, Watamull LM, Mullican MA.
J Urol. 1999;162:23–26.
This prospective study was designed to compare secondlook nephroscopy with CT and plain film radiography to detect residual calculi in patients following percutaneous nephrostolithotomy. All 3 modalities were used in 41 kidneys (36 patients) studied. CT detected the greatest number of residual calculi, 3.4 per renal unit, compared with 2.3 found with flexible nephroscopy and 0.7 with plain film radiography. Using second-look nephroscopy as the gold standard, the sensitivity and specificity for each of the other modalities were determined. The sensitivity and specificity were, respectively, 46% and 82% for plain film radiography and 100% and 62% for CT.
Routine flexible nephroscopy following percutaneous nephrostolithotomy has several drawbacks. It is expensive; the total cost reported in this study was more than $5000. It is invasive; 2 patients in this series had hydrothorax after flexible nephroscopy when it was performed without a sheath. (The authors now perform all flexible nephroscopy through a sheath to prevent this problem.) Most important: nephroscopy is frequently unnecessary; the procedure was not needed in 20% of the patients in this study. The authors determined that a significant cost savings would be possible if a CT scan was used as the initial method for detecting residual calculi.
The use of unenhanced helical CT to search for residual calculi after percutaneous stone treatment is a very sensitive method and may be the more cost-effective modality. The additional information gained from 3-dimensional imaging can facilitate percutaneous removal of residual fragments when necessary. I believe our goal with these patients is to render them stone-free. Postoperative CT scanning can help us achieve that goal. Even if it is felt that small, “clinically insignificant” fragments can be left in place, the CT scan will serve as the most accurate baseline study for future medical or surgical management.
13-Year Experience With Percutaneous Management of Upper Tract Transitional Cell Carcinoma
Clark PE, Streem SB, Geisinger MA.
J Urol. 1999;161:772–776.
These authors review their experience with the percutaneous endoscopic resection of TCC of the upper urinary tract in 18 kidneys from 17 patients. The mean age of the patients was 72 years, and the most common indication for nephron-sparing endoscopic management was a solitary kidney (71%). Percutaneous nephroscopy and resection of the tumor were performed, followed by secondlook nephroscopy 3 to 5 days later. A nephrostomy tube was left in place and, starting 2 weeks later, BCG treatment was used in 16 of the 18 kidneys for 6 weeks. A third-look nephroscopy was performed following completion of the BCG treatment, and follow-up consisted of cystoscopy and radiographic or endoscopic evaluation of the upper urinary tract every 3 to 6 months. Mean follow-up was 20.5 months (range, 1.7 to 75.5 months). Recurrences occurred in 6 renal units (33%) and were managed endoscopically in 4 patients and by nephroureterectomy in 2 patients. At latest follow-up, 65% of the patients were alive and without evidence of disease. Three patients (17.6%) died of TCC. There was a trend toward increased risk of recurrence and metastasis with higher grade and stage of tumor.
The percutaneous approach to the management of TCC of the upper urinary tract seems to be safe. One of the concerns regarding the percutaneous approach is the potential for seeding of the percutaneous tract with TCC, but no seeding was reported in this series. I prefer the ureteroscopic approach, when possible, to avoid violating the urothelium. As our instruments continue to improve, ureteroscopic evaluation and management of these transitional cell tumors should become safer and more successful.