The Guy's stone score--grading the complexity of percutaneous nephrolithotomy procedures.

OBJECTIVES: To report the development and validation of a scoring system, the Guy's stone score, to grade the complexity of percutaneous nephrolithotomy (PCNL). Currently, no standardized method is available to predict the stone-free rate after PCNL. METHODS: The Guy's stone score was developed through a combination of expert opinion, published data review, and iterative testing. It comprises 4 grades: grade I, solitary stone in mid/lower pole or solitary stone in the pelvis with simple anatomy; grade II, solitary stone in upper pole or multiple stones in a patient with simple anatomy or a solitary stone in a patient with abnormal anatomy; grade III, multiple stones in a patient with abnormal anatomy or stones in a caliceal diverticulum or partial staghorn calculus; grade IV, staghorn calculus or any stone in a patient with spina bifida or spinal injury. It was assessed for reproducibility using the kappa coefficient and validated on a prospective database of 100 PCNL procedures performed in a tertiary stone center. The complications were graded using the modified Clavien score. The clinical outcomes were recorded prospectively and assessed with multivariate analysis. RESULTS: The Guy's stone score was the only factor that significantly and independently predicted the stone-free rate (P = .01). It was found to be reproducible, with good inter-rater agreement (P = .81). None of the other factors tested, including stone burden, operating surgeon, patient weight, age, and comorbidity, correlated with the stone-free rate. CONCLUSIONS: The Guy's stone score accurately predicted the stone-free rate after PCNL. It was easy to use and reproducible.

Treatment of urolithiasis in the morbidly obese.

BACKGROUND: Morbidly obese patients with urolithiasis present a therapeutic and diagnostic challenge to the Urologist. Management is reported and potential difficulties discussed. METHODS: Morbidly obese patients (body mass index > or = 40kg/m2) with stone disease were identified by retrospective review. Stone load was calculated and treatment modalities noted. RESULTS: 18 renal units (kidneys) were treated in 17 patients. Of these, 2 required no treatment, 2 had open procedures, and 15 were treated with flexible ureteroscopy. Mean stone burden in patients treated with flexible ureteroscopy was 18 mm, but 8 patients had stone loads >15 mm and in these patients mean stone burden was 23 mm. All were successfully treated or rendered asymptomatic. There were no major complications. CONCLUSION: Obesity is increasingly prevalent and associated with a high incidence of co-morbidity and complications. Imaging can be difficult and treatment options are limited. Flexible ureteroscopy has proven to be the most successful treatment option, and can avoid the need for more invasive procedures. Furthermore, stone loads greater than normally acceptable can be successfully undertaken in these patients, and should be attempted due to problems associated with other techniques.

Baskets in the kidney: an old problem in a new situation.

A potential complication of using a zero-tip basket to remove stones from a lower-lower pole calix of the kidney is impaction in this position. We report an endourologic technique involving a hydrogel-coated ureteral dilator to facilitate closure of the wires and removal of the basket following lithotripsy to fragment the stone.

Management of encrusted ureteral stents impacted in upper tract.

OBJECTIVES: To present our series of patients with ureteral stent encrustation and give indwelling times and management. Encrustation is one of the most serious complications of ureteral stents. METHODS: A retrospective review was undertaken of all encrusted stents during a 4-year period. The inclusion criterion was a stent that required some form of intervention above the ureteral orifice to remove it. Combinations of extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, and open surgery were used to achieve stent removal. RESULTS: Forty-nine impacted encrusted stents were treated in 41 patients. Of these, 75.5% had become encrusted within 6 months and 42.8% within 4 months. The mean indwelling time was 5.6 months. Forty-seven stents were removed by endourologic techniques, with 4 requiring extracorporeal shock wave lithotripsy alone, 28 ureteroscopy, and 10 a combination of both. Five patients underwent successful percutaneous nephrolithotomy. One patient underwent open surgery, and in one removal failed. The mean number of procedures per patient was 1.94. CONCLUSIONS: Stent encrustation can pose a serious challenge to the endourologist, and indwelling times should be minimized to avoid problems. Patients often require multiple treatments and a combination of extracorporeal shock wave lithotripsy and ureteroscopy offers highly successful outcomes and often avoids the need for more invasive techniques.