Residual Stone Group Research Articles

Extracorporeal shock wave lithotripsy success based on body mass index and Hounsfield units

To determine whether body mass index (BMI) and Hounsfield units (HUs) could be used as independent predictors of stone-free status after extracorporeal shock wave lithotripsy (ESWL). No detailed studies have assessed BMI as an independent predictor of ESWL outcome. Some studies have suggested that HUs of urinary calculi on noncontrast computed tomography may predict the stone-free rate after ESWL. We evaluated 100 patients who had undergone ESWL for 5-mm to 10-mm upper urinary tract stones. The BMI was calculated for each patient. HU determination and chemical analysis was performed for each stone. Radiographic assessment at 6 weeks categorized patients into a stone-free (SF) or residual-stone (RS) group. Statistical analysis, using BMI and HUs as predictors, was performed to assess the stone-free rate after ESWL. Of 100 patients, 72 were in the SF and 28 in the RS group. The mean BMI for the SF group was 26.9 +/- 0.5 versus 30.8 +/- 0.9 in the RS group (P <0.05). The difference in the mean HU values for the SF and RS groups was statistically significant (577.8 +/- 182.5 versus 910.4 +/- 190.2, respectively; P <0.05). A successful outcome was significantly related to BMI (odds ratio 1.34, 95% confidence interval 1.09 to 1.65, P <0.01) and HUs (odds ratio 1.01, 95% confidence interval 1.007 to 1.019, P <0.01). The following equation was formulated to compute the probability of treatment failure: 1/1 + 2.7(-z), where z = 0.294 BMI + 0.13 HU - 18.98. BMI and HUs were statistically significant independent predictors of stone-free rates after ESWL. We believe a predictive model of ESWL outcome may be formulated on the basis of these findings and may be used to select the preferred treatment option for patients with urinary calculi.

THE IMPACT OF CALICEAL PELVIC ANATOMY ON STONE CLEARANCE AFTER SHOCK WAVE LITHOTRIPSY FOR PEDIATRIC LOWER POLE STONES

The clearance rather than stone disintegration of lower pole stones after shock wave lithotripsy (SWL) is significantly inferior according to the other localizations of the kidney. We retrospectively evaluated the impact of caliceal pelvic anatomy on stone clearance after SWL for pediatric lower pole stones. We treated 163 renal units (RUs) in children 16 years old or younger with SWL between March 1992 and February 2002. In 36 RUs stones were localized in the lower calices. All patients were treated with sedoanalgesia except 3 (8%) who were treated under general anesthesia. Patients were evaluated by excretory urography and ultrasonography 12 weeks after the last session, and were designated as stone-free or with residual stone. The lower infundibular length, width, length-to-width ratio, pelvic caliceal height and lower infundibulopelvic angle were determined on standard excretory urography before SWL. All measurements were done by 1 urologist who was unaware of the results. Statistical analysis was performed with chi-square, Fisher's exact and Mann-Whitney U tests. ROC analysis was done to determine the cutoff points of caliceal anatomy measurements for stone clearance. We treated 36 RUs in 23 males and 10 females with isolated lower caliceal stones. Median patient age was 10.5 years (range 2 to 16). Median stone burden was 0.7 cm (range 0.2 to 4), and median number of shock waves and energy used for the entire patient population was 1,500 and 17.2 kV, respectively. Overall stone-free rates for the 36 RUs were 61% after a median treatment session of 1 (range 1 to 7) and retreatment rates were 39%. Of the patients rendered free of stones 13 (59%) were treated in a single SWL session and 9 (41%) underwent 2 or more sessions. Median lower infundibular length, width, length-to-width ratio and pelvic caliceal height in the stone-free and residual stone group were 25.5, 28.0 mm, 4.5, 5.0 mm, 6.4, 5.5 mm and 21.5, 21.5 mm, respectively (p = 0.810, 0.327, 0.511 and 0.511). Median lower infundibulopelvic angle in the stone-free and residual stone groups was 92.50 and 92.50 degrees, and 60.0 and 54.50 degrees, respectively (p = 0.860 and 0.089). On ROC analysis no parameter predicting stone-free rate and cutoff points of caliceal anatomy measurements for stone clearance was found. Our results suggest that caliceal pelvic anatomy in pediatric lower pole stones has no significant impact on stone clearance after SWL. There was a highly significant relation between retreatment rates and stone burden, which should be considered for determining the treatment modality.

Hounsfield Units on Computerized Tomography Predict Stone-Free Rates After Extracorporeal Shock Wave Lithotripsy

Studies suggest that HU values on non-contrast computerized tomography may predict the ability to fragment urinary calculi. We determined whether the HUs of in vivo urinary stones could be used to predict the stone-free rates after extracorporeal shock wave lithotripsy. We evaluated 50 patients who underwent extracorporeal shock wave lithotripsy for 5 to 10 mm. upper urinary tract stones. Chemical analyses and HU calculations were performed for each stone and posttreatment radiographic assessment categorized patients into a stone-free or a residual stone group. Statistical analysis was performed using the Student t test to compare mean HU values in the 2 groups. Of the patients 32 (64%) were stone-free and 18 (36%) had residual stones. Mean values +/- SEM for the stone-free and residual stone groups were significantly different (551.20 +/- 46.66 versus 926.20 +/- 51.42 HU, p <0.0001). A total of 30 calculi (60%) were located in the ureter, including 21 in the stone-free group and 9 in the residual stone group with a mean value of 505.10 +/- 46.66 and 888.70 +/- 102.00 HU, respectively, which was significantly different (p = 0.0005). A total of 20 calculi (40%) were located in the kidney, including 11 in the stone-free group and 9 in the residual stone group with a mean value of 558.40 +/- 62.38 and 905.10 +/- 61.49 HU, respectively, which was significantly different (p = 0.001). These findings suggest that HU measurement of urinary calculi on pretreatment non-contrast computerized tomography may predict the stone-free rate. This information may be beneficial for selecting the preferred treatment option for patients with urinary calculi.

Usefulness of lower ihfundibular length-to-diameter ratio as a predictor of lower pole stone clearance after extracorporeal shock wave lithotripsy; clinical research with two lithotriptors

Lower pole renal stones are well known to exhibit a poor stone clearance rate following extracorporeal shock wave lithotripsy (ESWL). In the present study, we analyzed several anatomical factors as predictors of lower pole stone clearance that may be used to indicate the usefulness and the universality of ESWL in such patients with two different lithotriptors. 93 patients with a unilateral single lower pole stone of 2 cm. or less underwent ESWL using Piezolith 2500 or Medstone STS, were included in the study. An IVP was used to determine the lower infundibulopelvic angle, the caliceal pelvic height, the lower infundibular length, the lower infundibular diameter, the lower infundibular length-to-diameter ratio and the number of lower pole minor calyces. Stone-free status was assessed by a plain film with or without renal ultrasound. The stone clearance rate at the Piezolith 2500 group was 53.1% (34 of 64 patients), while was 51.7% (15 of 29 patients) at the Medstone STS group. In all cases, the overall stone clearance rate was 52.7% (49 of 93 patients). Age, laterality of the stone burden within the kidney and stone size were not different between the stone-free and residual stone groups. Multivariate logistic analysis revealed that length-to-diameter ratio was the most independent predictors of successful stone clearance at each group. The patients exhibited length-to-diameter ratio less than 7 achieved high stone clearance rates, greater than 72%. In contrast, the stone clearance rate was less than one third when length-to-diameter ratio was 7 or greater. Besides length-to-diameter ratio was strong prognostic factor in patients with stones 1 cm. or less and 1 to 2 cm at each group. From this study, it is apparent that successful ESWL is highly sensitive to the anatomy of the lower pole of the kidney. Especially, the lower infundibular length-to-diameter ratio is potentially useful and a universal predictor regardless of the kind of lithotriptors at least in patients with a lower pole radiopaque stone 2 cm. or less treated with ESWL.

Predictors of Lower Pole Renal Stone Clearance After Extracorporeal Shock Wave Lithotripsy

Lower pole renal stones are well known to show a poor stone clearance rate after extracorporeal shock wave lithotripsy (ESWL) (Dornier Medical Systems, Marietta, Georgia). In the current study we analyzed several anatomical factors as predictors of lower pole stone clearance that may be used to indicate the usefulness of ESWL in such patients. Between January 1993 and October 2000, 63 patients with a unilateral single lower pole stone of 2 cm. or less were included in the study. Excretory urography was done to determine the lower infundibulopelvic angle, caliceal pelvic height, lower infundibular length and diameter, lower infundibular length-to-diameter ratio and number of lower pole minor calices. Stone-free status was assessed by x-ray. The overall stone clearance rate was 54% (34 of 63 patients). While caliceal pelvic height, lower infundibular diameter, length, length-to-diameter ratio and number of minor calices were different in the stone-free and residual stone groups on univariate analysis, multivariate logistic analysis revealed that the lower infundibular length-to-diameter ratio, diameter and number of minor calices were independent predictors of successful stone clearance. The 13 patients (20.6%) who showed all 3 favorable anatomical factors (lower infundibular length-to-diameter ratio less than 7, diameter greater than 4 mm. and a single minor calix) achieved an impressive 84.6% stone clearance rate. In patients with only 1 or 2 favorable factors the stone clearance rate was still greater than 60%. In contrast, the stone clearance rate was only 6.7% in the 15 patients who showed none of these factors. From this study it is apparent that successful ESWL is highly sensitive to the anatomy of the lower pole of the kidney. If a patient with a lower pole stone has at least 1 of the favorable factors identified in this study, ESWL may be advocated as first line therapy with a greater than 60% prospect of a successful outcome. Other treatment options should be considered in those without any of these predictive factors.

Surgical treatment of hepatolithiasis: Long-term results

Hepatolithiasis is a common disease in East Asia and is prevalent in Taiwan. Surgical and nonsurgical procedures for management of hepatolithiasis have been discussed, but long-term follow-up results of surgical treatment of hepatolithiasis are rarely reported. We conducted a retrospective study of case records of patients with hepatolithiasis who underwent surgical or nonsurgical percutaneous transhepatic cholangioscopy treatment. Of 614 patients with hepatolithiasis seen between January 1984 and December 1988, 427 underwent follow-up after surgical (380) or percutaneous transhepatic cholangioscopy (47) treatment for 4 to 10 years and constituted the basis of this study. Long-term results of 427 patients with hepatolithiasis after surgical and nonsurgical treatment within 4 to 10 years of follow-up were recurrent stone rate 29.6% (105 of 355), repeated operation 18.7% (80 of 427), secondary biliary cirrhosis 6.8% (29 of 427), late development of cholangiocarcinoma 2.8% (12 of 427), and mortality rate 10.3% (44 of 427). The patients with hepatectomy had a better quality of life (symptom-free) with a lower recurrent stone rate (9.5%), lower mortality rate (2.1%), and lower incidence of secondary biliary cirrhosis (2.1%) and cholangiocarcinoma (0%) than did the nonhepatectomy group (p < 0.01). The patients without residual stones after choledochoscopy had a better quality of life than did the residual stone group (p < 0.01). Long-term follow-up study of hepatolithiasis after surgical treatment revealed a high recurrent stone rate (29.6%) that required repeated surgery and a high mortality rate (10.3%) resulting from repeated cholangitis, secondary biliary cirrhosis, and late development of cholangiocarcinoma. Patients who received hepatectomy or without residual stones after choledochoscopy had a good prognosis and quality of life.