ESWL monotherapy for large-volume renal calculi: efficacy and morbidity

Evaluation of the impact of shock wave lithotripsy on kidneys using a new marker: how do neutrophil gelatinese-associated lypocalin values change after shock wave lithotripsy?

OBJECTIVE

To determine possible acute kidney injury with new marker neutrophil gelatinase-associated lipocalin (NGAL) in urine and to show the relationship between changes of this marker and conventional markers in patients undergoing shock wave lithotripsy (SWL).

METHODS

In patients with kidney stones, serum urea, creatinine, urine microalbumin, and NGAL levels were determined before SWL and at the first, second, and seventh days after SWL. In addition, patients who had undergone SWL were evaluated with Technetium-99m (Tc99m)-dimercaptosuccinic acid (DMSA) and Tc99m-diethylenetriaminepenta acetate renal scintigraphy 1 week before and 3 months after SWL.

RESULTS AND LIMITATIONS

Forty patients were included in the study. All patients had a single stone in the kidney with an average size of 9.25 mm (range 5-15). No statistical change was found in the levels of average serum urea and creatinine levels, urine microglobulin, and NGAL levels, which were measured before SWL and after SWL. No significant difference was identified in urine NGAL and microalbumin levels of the groups, which were separated by shock wave number and shock energy amount on the first, second, and seventh days after SWL. In the high-energy SWL group, 3 patients had a statistical decrease in their differential kidney function measured with Tc99m difference between differential function rates of the kidney before and after SWL (DMSA) after 3 months after SWL.

CONCLUSION

Our study found that, using both new and conventional parameters in the acute stage and 3 months later, SWL treatment does not cause acute kidney damage.

What is the Role of Retrograde Ureteroscopy in the Management of Large Renal Calculi?

Background and purpose:

The management of large renal calculi has traditionally been with percutaneous nephrolithotomy (PCNL) or occasionally extracorporeal shock wave lithotripsy (ESWL). We present our experience of ureteroscopic treatment of large renal calculi in patients where PCNL/ESWL were contraindicated, refused or failed.

Patients and methods:

Data from 30 patients with intra-renal calculi ≥20 mm was prospectively entered onto a database and analysed. Patients were treated with rigid and flexible ureteroscopy (URS) using holmium laser or lithoclast (pneumatic) lithotripsy.

Results:

Mean stone size was 2.8cm (range 2.0–6.0cm). The most common indications were ESWL failure (40%), anatomical reasons (20%), patient choice (10%) and failed PCNL access (7%). Stone clearance (no fragments >3 mm on follow-up imaging) was observed after one URS treatment alone in 30% of patients and a further 27% with a post-operative session of ESWL. Two URS sessions alone were used in 23% of patients, with a single patient needing two URS and post-operative ESWL. Three URS sessions plus ESWL was used in 7% of patients. Three patients (10%) required PCNL. Median operative time was 60min. Complications were minimal: four patients had urinary tract infection, one failed trial without catheter, one atrial fibrillation, and one stent migration.

Conclusion:

Where PCNL is not favoured for any reason, patients with a large stone burden can be safely and effectively managed with retrograde URS, either with the intention of stone clearance or de-bulking prior to ESWL.

Clinical Insignificant Residual Fragments (CIRF) after Extracorporeal Lithotripsy: Implications and Treatment

The stone-free status depends on the appropriate selection of the urologic treatment according to the stone and excretory tract characteristics, and/or to the patient parameters.

Although the gold standard for the treatment is the stone-free status, the authors believe that the presence of non-infected, nonobstructive, asymptomatic residual fragments, smaller than 4–5 mm, can be treated with an adequate medical therapy in order to prevent stone growth. Further urological treatment is recommended if the clinical indications for stone removal persist.

Use of a neural network to predict stone growth after shock wave lithotripsy

OBJECTIVES

To determine whether a neural network is superior to standard computational methods in predicting stone regrowth after shock wave lithotripsy (SWL) and to determine whether the presence of residual fragments, as an independent variable, increases risk.

METHODS

We reviewed the records of 98 patients with renal or ureteral calculi treated by primary SWL at a single institution and followed up for at least 1 year; residual stone fragment growth or new stone occurrence was determined from abdominal radiographs. A neural network was programmed and trained to predict an increased stone volume over time utilizing input variables, including previous stone events, metabolic abnormality, directed medical therapy, infection, caliectasis, and residual fragments after SWL. Patient data were partitioned into a training set of 65 examples and a test set of 33. The neural network did not encounter the test set until training was complete.

RESULTS

The average follow-up period was 3.5 years (range 1 to 10). Of 98 patients, 47 had residual stone fragments 3 months after SWL; of these 47, 8 had increased stone volume at last follow-up visit. Of 51 patients stone free after SWL, 4 had stone recurrence. Coexisting risk factors were incorporated into a neural computational model to determine which of the risk factors was individually predictive of stone growth. The classification accuracy of the neural model in the test set was 91%, with a sensitivity of 91%, a specificity of 92%, and a receiver operating characteristic curve area of 0.964, results significantly better than those yielded by linear and quadratic discriminant function analysis.

CONCLUSIONS

A computational tool was developed to predict accurately the risk of future stone activity in patients treated by SWL. Use of the neural network demonstrates that none of the risk factors for stone growth, including the presence of residual fragments, is individually predictive of continuing stone formation.

Minor residual fragments after extracorporeal shockwave lithotripsy: spontaneous clearance or risk factor for recurrent stone formation?

The aim of this study was to follow the fate of residual stone fragments (RF) < 5 mm after extracorporeal shockwave lithotripsy (SWL) over a sufficiently long period to determine how many are spontaneously cleared and after what time interval. A further aim was to clarify their role in clinical outcome and stone recurrence and regrowth. The clinical and radiologic data of 266 patients were analyzed. The patients were followed up for a mean of 387 days. After SWL, 55 patients (21%) had residual fragments < 5 mm in diameter. There were no significant differences between the stone-free patients and those with RF with regard to age, sex, relevant medical history, or SWL treatment. After a mean follow-up of 2.5 years, 12.7% of the residual fragments had not passed spontaneously, but all of them were clinically silent and located exclusively in the lower calices and the proximal ureter. Only 2% of the patients with RF showed stone regrowth, and no stone recurrences were observed within the follow-up period. In conclusion, although a minor pathophysiological role of RF < or = 5 mm cannot be discounted in recurrence and regrowth of kidney stones after SWL, more invasive attempts to clear all minor fragments do not seem warranted.