Cephalad renal movement during percutaneous nephrostolithotomy

Renal Displacement with Supine to Prone Positional Change: Effect of Sex and BMI

OBJECTIVE

To determine patterns of kidney and retroperitoneal organ movement during positional change between the supine and prone positions as seen on computed tomography (CT) scans.

METHODS

Axial CT scans of 75 subjects who underwent supine and prone were retrospectively analyzed. A total of 1650 measurements were taken for anterior-posterior, medial-lateral, cranial-caudal, skin-to-calyx distance, kidney-to-liver distance, and kidney-to-colon distance in both positions.

RESULTS

Pronation shortens the distance from the skin to renal calyx for both the right (99.62 mm vs. 85.14 mm; p < 0.00001) and left (96.67 mm vs. 90.80 mm; p < 0.00001) sides. The reduction in left-side tract length for obese patients is significantly greater than that of normal weight patients (11.88 mm vs. -5.02 mm; p = 0.001). The left kidney displaces ventrally (11.12 mm vs. 18.59 mm; p < 0.00001) while the right kidney does not (14.26 mm vs. 15.30 mm; p = 0.30). The right kidney displaces cranially (62.76 mm vs. 79.51 mm; p < 0.00001) while the left kidney does not (64.35 mm vs. 66.52 mm; p = 0.14). The left kidney in females moves medially while no change is seen in males (4.22 mm vs. -0.48 mm; p = 0.0004). The left kidney in females displaces towards the descending colon while it moves farther away in males (2.73 mm vs. -2.01 mm; p = 0.011).

CONCLUSIONS

Both sex and BMI had effects on the movement of the kidneys upon pronation. The differences can be clinically useful to help pre and intraoperative planning.

Multitract percutaneous nephrolithotomy in staghorn calculus

Staghorn calculi are branched stones which occupy a majority portion of the pelvicaliceal system. An untreated staghorn calculus over time can damage the kidney and deteriorate its function and/or cause life threatening sepsis. Total stone clearance is an important goal in order to eradicate any infective focus, relieve obstruction, prevent recurrence and preserve the kidney function. Percutaneous nephrolithotomy (PCNL) is currently the accepted first-line treatment option for staghorn calculi. The options available are single-tract PCNL with an auxiliary procedure like shockwave lithotripsy, single-tract PCNL with flexible nephroscopy, or multitract PCNL. Each has its own pros and cons. But the ultimate goal of treatment for any patient with staghorn calculi should be safety, cost-effectiveness, and to achieve total stone clearance. With this article, we review the management of staghorn calculi with multiple percutaneous (“multitract”) access, its advantages and disadvantages and its current position by studying the various published materials across the globe.

Percutaneous Nephrolithotomy via a Middle Calyx Access Is Effective in the Treatment of Lower Pole Kidney Stones: A Single-Center Study

PURPOSE

To compare the efficacy of the middle calyx access (MCA) and lower calyx access (LCA) in the treatment of lower pole kidney stones.

MATERIALS AND METHODS

The data of patients with isolated lower pole kidney stones who underwent percutaneous nephrolithotomy via MCA or LCA between 2009 and 2019 were evaluated retrospectively. Pre-, peri-, and postoperative parameters of the groups (LCA group and MCA group) were compared. A value of p < 0.05 was considered significant.

RESULTS

A total of 601 patients with lower pole kidney stones were included in the study. LCA was performed for the initial tract in 400 patients, and MCA was performed in 201 patients. There were no significant differences in terms of age, gender, laterality, body mass index, previous operation history, stone burden, duration of fluoroscopy, and stone-free rate between the groups. Operation time was significantly longer in the LCA group (p = 0.041). In the LCA group, additional access was required in 50 cases, which was significantly higher than in the MCA group (p = 0.013). Clinically insignificant residual fragments (CIRF) were present in 28 patients (7%) in the first group (significantly higher vs. MCA: p = 0.044). There were no statistically significant differences in terms of overall complication and transfusion rates.

CONCLUSIONS

MCA had superior outcomes in terms of operation time, CIRF rate, hemoglobin drop, and requirement of an additional tract compared to LCA. Further studies evaluating the efficacy of MCA in lower pole kidney stones should be performed to verify our results.

Movement of target organs and anatomical landmarks caused by body position change during urological laparoscopic surgery

INTRODUCTION

The aim of our study was to elucidate the impact of patients' physical characteristics on the movement of target organs and anatomical landmarks by comparing supine and lateral CT images.

METHODS

This study consisted of 55 patients who underwent laparoscopic surgery in the lateral position. CT images of the area between the abdomen and pelvis were taken preoperatively with patients in both supine and lateral positions. We measured the moving distance of target organs and anatomical landmarks on the body surface used for access port settings. We investigated which covariates from patients' body composition most affected moving distance in correlation analysis. Then, using multiple linear regression analysis, we examined whether we could predict the movement of target organs and anatomical landmarks solely based on information obtained from supine CT images.

RESULTS

The moving distance of both the hilum of the kidney and the outer edge of the rectus abdominis muscle were significantly associated with some physical characteristics. Multiple regression analysis showed that a larger visceral fat area could be a useful index for predicting the movement of the kidney toward the counter side. Lower CT density of back muscles and higher BMI could be useful indexes for predicting the movement of the rectus abdominis muscle.

CONCLUSION

Our results suggested that body composition characteristics obtained from preoperative CT images can help predict the movement of target organs and anatomical landmarks used to determine proper port-site placement for laparoscopic surgery performed with the patient in the lateral position.

Supracostal Punctures for PCNL: Factors that Predict Safety, Success and Stone Free Rate in Stag Horn and Non-Stag Horn Stones: A Single Centre Experience and Review of Literature

INTRODUCTION

Supra-costal Percutaneous Nephrolithotomy (PCNL) procedure has now become an established standard of care in patients with renal stone disease, in terms of morbidity, stone clearance, duration of stay and shorter convalescence period. Gone are the days when supracostal punctures were considered to be associated with a high morbidity. With increased expertise gained in performing multiple punctures and further refinements in focusing techniques, more and more of these procedures are being performed with an intention to achieve a maximum stone clearance with least morbidity.

AIM

To prospectively analyze the various factors that predict the safety, efficacy and stone clearance rate in patients who have undergo supracostal punctures for PCNL procedures.

MATERIALS AND METHODS

Three hundred seventy six patients underwent PCNL for renal stones. Ninety two (n=92) of them needed supra-costal puncture. All patients were subdivided into groups 1 and 2 based on the size, location of the stone and the stone burden. In all, 132 tracts were established.

RESULTS

About 83% of patients achieved a complete stone free rate after initial PCNL. Stones more than 3 centimeters were found to be associated with significant residual stones. Radio opacity under image intensifier also had a significant impact on the ultimate stone free status. About 23% of those (n=5/22) who needed longer duration of surgery had a clinically significant residual stones, needing ancillary procedures. Fifteen patients (16%) had complications related to the procedure, of which 13 were in group 1 (87%). High percentage of complications in patients with larger stone burden was found to be statistically significant. In about 76% (n=70), the procedure required only less than 90 minutes. Also, in those 22 patients in whom the duration of procedure exceeded 90 minutes, 12 of them had complications, with a p-value of <0.0001.

CONCLUSION

Supra-costal punctures are safe and effective options in a selected group of patients. The overall results are almost on par with that of the infra costal punctures, with an acceptable morbidity.

A supracostal approach for percutaneous nephrolithotomy of staghorn calculi: A prospective study and review of previous reports

OBJECTIVES

To evaluate a supracostal approach for percutaneous nephrolithotomy (PCNL) of staghorn calculi through a prospective study and review of previously reported cases.

METHODS

From June 2009 to November 2011, 40 patients with staghorn calculi were scheduled for supracostal S-PCNL in a prospective study. Of the 40 renal units, 16 (40%) had a complete staghorn and 24 (60%) had a partial staghorn calculus. Perioperative complications were stratified according to the modified Clavien system. Univariate and multiple logistic regression analyses were used to determine statistically significant variables affecting the stone-free rate and development of complications.

RESULTS

In all, 57 tracts were established in the 40 renal units; 23 (58%) renal units were approached through one supracostal upper pole calyx, while 13 (33%) and four (10%) required a second middle- or lower-pole puncture, respectively. Overall, 78% of patients were rendered stone-free or had clinically insignificant residual fragments with PCNL monotherapy, and this increased to 88% with auxiliary procedures. In the logistic regression analysis, a complete staghorn stone was the only independent variable for residual stones (P = 0.005). There was an overall complication rate of 38%. Independent variables with an influence on complications were staghorn stone burden (P = 0.007), and operative duration (P = 0.045).

CONCLUSIONS

The supracostal upper calyceal approach provides optimum access for the percutaneous removal of staghorn stones. Appropriate attention to the technique and to monitoring before and after surgery can detect thoracic complications, and these can be managed easily with intercostal chest tube drainage, with no serious morbidity.

Supine versus prone position in percutaneous nephrolithotomy for kidney calculi: a meta-analysis

BACKGROUND

Supine position and prone position were the choice for percutaneous nephrolithotomy (PCNL). However, there is still no consensus on the optimal position for PCNL.

METHODS

A systematic literature review was performed, searching Pubmed, Embase, CENTRAL and reference lists for relevant studies. Data from all selected articles were extracted independently by two reviewers and analyzed by RevMan 5 software.

RESULTS

Four comparative studies involving 389 cases and 27 case series studies including 1,469 renal units of supine position and 4,837 renal units of prone position were identified. With reference to comparative studies, the mean stone length and the proportions of staghorn and multiple stones were comparable between two positions. There was no significant difference in terms of stone-free rate (risk ratio = 1.00, 95% confidence interval: 0.92 to 1.09; 82.4 vs. 82.1%) and bleeding. The rate of colonic injury in supine PCNL was approximate 0.5% and incidence of pleural injury of 0% was noted for both positions. Pelvic perforation and failed access were comparable between supine and prone position. The operative times of supine position significantly decreased (65±15 vs. 90±15 min; mean difference = -24.76, 95% confidence interval: -39.36 to -10.15), but no significant difference was found in mean days hospital stay. Analysis based on the case series showed larger proportion of staghorn and multiple calculi in prone position (45.8 vs. 31.7%), the supine PCNL had slightly lower bleeding and similar stone-free rate compared with the prone position.

CONCLUSIONS

For general patients with kidney calculi, PCNL in supine position has similar stone-free rate compared with prone. Supine PCNL do not increase related complications. The operative times significantly decrease in supine position.

A radiological investigation of the hepatorenal space: the importance of the ventral decubitus for safer percutaneous right renal access

We investigated anatomical and radiological morphometric parameters, aiming to minimize the risk of hepatic and colonic injuries during right percutaneous kidney access under either ventral or dorsal decubitus of patients. Prone and supine abdominal computerized tomographic examinations from 31 normal adult volunteers (men = 12; women = 19; without history of abdominal pathology) were analyzed morphometrically in order to study the dynamic anatomical relations between the liver and the right kidney. The age of the volunteers ranged from 22 to 64 years old (mean +/- SD = 42.77 +/- 2.10). We observed a significantly greater distance between the liver and the right kidney (hepatorenal space) when the examinee is positioned in ventral decubitus (3.93 +/- 0.37 cm) in comparison with dorsal decubitus (1.98 +/- 0.20 cm). Accordingly, we conclude that right percutaneous access to the inferior right renal pole implies a significantly lower risk (P < 0.01) of both hepatic and biliary injuries when performed in ventral decubitus, comparatively to dorsal decubitus.

Supra-twelfth supracostal access: when and where to puncture?

BACKGROUND AND PURPOSE

Supracostal access for percutaneous renal surgery raises concern for the intrathoracic complications of the puncture. We analyzed the incidence of pleural transgression and intrathoracic complications after supracostal punctures in relation to the site of puncture (medial v lateral placement) and the respiratory phase during the puncture.

PATIENTS AND METHODS

We conducted a prospective study of 28 consecutive supracostal accesses in our department. All the punctures were made by the treating urologist under fluoroscopic guidance. Punctures were made during the normal respiratory cycle, and dilatation was up to 30F. Postoperatively, chest radiography and CT of the chest and upper abdomen were performed for evaluation of complications.

RESULTS

All supracostal accesses were supra-12th rib only. The average distance from midline of the site of puncture on the skin was 8.2 cm (range 5.5-9.1 cm). Complete stone clearance was achieved in 27/28 (96.4%) of the renal units. One patient had symptomatic hydrothorax necessitating chest tube placement. None of the patients had any lung or solid organ (liver or spleen) injury on CT imaging. Three patients had mild pleural effusion without symptoms, which was detected on postoperative CT.

CONCLUSION

Laterally placed supra-12th rib punctures made during the normal ventilatory cycle have an acceptably low pleural morbidity and no risk of lung injury.

Tubeless PCNL with patient in supine position: procedure for all seasons?--with comprehensive technique

OBJECTIVES

Percutaneous nephrolithotomy (PCNL) has historically been performed with the patient in the prone position, which has inherent drawbacks. Supine PCNL has numerous benefits in terms of safety, efficacy, and versatility and is comparable with respect to vascular and bowel injury. This study was intended to prove that PCNL with the patient in the supine position is an alternative method of doing PCNL along with comprehensive technique.

METHODS

A total of 184 patients with 191 renal units underwent tubeless supine PCNL from 2005 to May 2007. Their mean age was 32 years and mean weight 62 kg. After insertion of a retrograde 5F ureteral catheter, the patient was placed in the supine position with a small towel roll under the ipsilateral flank, raising it by 20 degrees. Caliceal entry was achieved with an 18-gauge spinal needle, and the tract was dilated up to 27F with Alkans dilators over a 0.032-in. guidewire using fluoroscope only, with the patient under general anesthesia.

RESULTS

Primary stone clearance was achieved in 84% patients. Of the 184 patients, 94% had a single and 6% had a double tract; 72% of patients had a lower, 25% a middle, and 3% an upper caliceal puncture. The mean single stone size was 3.5 cm, and the mean multiple stone burden was 12 cm. No vascular or splanchnic injury or bowel transgression was observed. Tubeless PCNL was possible in 87% patients; 4% patients required transfusion, and 1 patient each had a perinephric collection and a plural effusion.

CONCLUSIONS

Tubeless PCNL with the patient in the supine position is an independent method of treating renal stones without complementing PCNL in the prone position. It adds ease and comfort to the patient, anesthesiologist, and surgeon.

Anesthetic considerations during percutaneous nephrolithotomy

STUDY OBJECTIVE

To assess anesthesia-related complications during and following percutaneous nephrolithotomy (PCNL) for staghorn stones.

DESIGN

Prospective study and a detailed case report.

SETTING

Medical center in southern Israel.

PATIENTS

20 consecutive patients undergoing PCNL for staghorn stones.

INTERVENTIONS

All patients underwent PCNL during general anesthesia.

MEASUREMENTS

Duration of surgery, esophageal temperature, hemoglobin (Hb) concentration, and requirements for blood transfusion, mean volume of irrigation fluid, and serum sodium and potassium concentration were recorded.

MAIN RESULTS

Mean age was 50.7 +/- 14.9 y (range, 26-76 y). Mean duration of the procedure was 120.0 +/- 42.5 min (range, 75-240 min). Mean volume of irrigation fluid was 34.1 +/- 15.3 L (range, 18-80 L). There was a significant decrease in Hb concentration from 13.7 +/- 1.71 to 12.2 +/- 1.4 g/dL, but no patient required blood transfusion. There was a statistically significant reduction in esophageal temperature from 36.4 degrees C +/- 0.32 degrees C to 35.2 degrees C +/- 0.5 degrees C. There were no significant changes in sodium or potassium concentration before or after PCNL.

CONCLUSIONS

Anesthesia during PCNL for staghorn stones is a challenge because of the possibility of fluid absorption, dilutional anemia, hypothermia, or significant blood loss.

Safety of supracostal punctures for percutaneous renal surgery

AIM

Supracostal superior calyceal access has been shown to be the most suitable approach for staghorn calculi, calculi in the upper ureter and complex inferior calyceal calculi, as well as for antegrade endopyelotomy. However, many urologists hesitate in using this approach because of the potential for chest complications. The aim of this study was to analyze one institution's data regarding the safety and efficacy of this approach for percutaneous renal surgery.

METHODS

A total of 890 renal units (762 patients) were treated with percutaneous renal surgery (849 percutaneous nephrolithotomy, 41 antegrade endopyelotomy) from July 1998 to July 2004. Supracostal access was obtained in 332 (37.3%) patients. The indications for a supracostal approach were ureteropelvic junction obstruction, staghorn and complex inferior calyceal calculi, and stones in the upper calyx or the upper ureter. All punctures were made by the urologist under C-arm fluoroscopic guidance in the prone position.

RESULTS

The interspace between 11th and 12th rib was used in all except four patients in whom the puncture was made above the 11th rib. Eleven patients (3.31%) had a pleural breach presenting with fluid in the chest. Insertion of a chest tube was required in seven patients, while other four were managed conservatively. No patient had injury to the lung or other viscera. Hospital stay was not significantly prolonged as a result of the pleural breach in any patient. Except for staghorn calculi where multiple tracts were a necessity for maximal clearance, a single supracostal superior or middle posterior calyceal access served the purpose in 86% (177/205) of patients who underwent percutaneous surgery for renal or upper ureteric calculi.

CONCLUSIONS

The supracostal superior calyceal approach was found to be effective as well as safe, with an acceptably low risk of chest complications.

Upper pole access for complex lower pole renal calculi

OBJECTIVES

To assess the efficacy of superior pole access for complex lower pole calyceal calculi.

PATIENTS AND METHODS

In all, 102 patients with complex inferior calyceal calculi were included in a prospective unrandomized study. Complex inferior calyceal calculi were defined as multiple calculi in two or more inferior calyces of the lower polar group, with each calyx draining through a separate infundibulum and at an acute angle to each other. In 33 patients (32%; group 1) an inferior calyceal puncture was made and in 69 (68%; group 2) access was obtained through a superior calyceal puncture. The stone-free rates, decrease in haemoglobin, operative duration, requirement for additional tracts and second procedures in the two groups were compared.

RESULTS

Stone clearance rates and blood loss values were better in group 2, although they were not significantly different. The mean operative duration, number of tracts required and the re-look procedure rate was significantly less in group 2. Two patients (3%) in group 2 had hydrothorax related to supracostal puncture and required chest tube insertion.

CONCLUSIONS

Superior calyceal puncture (supracostal or infracostal) affords optimum access to complex inferior calyceal stones, providing faster and better clearance with a single puncture, and less requirement for second-look procedures.

Isolated severe renal injuries after minimal blunt trauma to the upper abdomen and flank: CT findings

Renal injuries caused by blunt abdominal trauma are common in children. Serious renal trauma is associated with insult to other organs, whereas isolated renal injuries are usually minor. We present the cases of six male children (aged 7-17 years) with major isolated renal injuries due to minimal blunt trauma to the upper adbomen and/or the flank, out of a total of 21 children admitted with renal trauma in a 5-years period. On physical examination all patients had a painful, tender abdomen and/or flank with ipsilateral bruises and ecchymosis. Hematuria, either macro ( n=4) or micro ( n=2), was found in all. The injuries were left-sided in five and were of a variable severity (grade III: n=2; grade IV: n=3; grade V: n=1 according to the kidney injury scale of the American Association for the Surgery of Trauma). Four children underwent nephrectomy. This small series underlines that major kidney insult can occur after a minimal blunt trauma localized to the flank or upper abdomen. Abdominal CT should be performed when clinical or laboratory findings or the mechanism of trauma suggest renal injury.

Changes in the size and location of kidneys from the supine to standing positions and the implications for block placement during total body irradiation

PURPOSE

The use of total body irradiation (TBI) as a conditioning regimen for bone marrow transplantation often calls for partial transmission kidney blocks. These blocks are frequently designed based on the location of the kidneys during the abdominal computerized tomography (CT) scan. At our institution, TBI patients are treated in the standing position. As the kidneys can shift with different patient positions, a study was undertaken to evaluate the magnitude of the changes in the size and location of the kidneys from the supine CT position to the upright treatment position.

METHODS AND MATERIALS

Intravenous contrast was administered to 15 patients. The patients were initially positioned supine on a simulator table and then positioned upright immediately in front of the image intensifier. PA radiographs were obtained with the patients in both positions. Changes in the size of the kidneys and their location relative to the vertebral bodies were noted.

RESULTS

In going from the supine to upright position, all the kidneys shifted inferiorly between 0.5 cm and 7.5 cm with an average of 3.6 cm. Most of the kidneys also shifted in the transverse dimension and incurred a change in width. The range of the transverse shift was from 0.9 cm in the lateral direction to 4.9 cm medially. The maximum width broadening was 1.2 cm and the maximum decrease in width was 1.8 cm.

CONCLUSIONS

When compared to the supine position, patients in the upright position show a dramatic inferior shift of the kidneys with other obvious, but less predictable, changes. For TBI treatments delivered in the upright position, kidney blocks should not be designed on the basis of supine abdominal CT scans.

The effect of patient position on intrarenal anatomy

BACKGROUND AND OBJECTIVE

Although flexible ureteroscopes are designed with mechanisms for active and passive tip deflection, one of the major problems is the not infrequent inability to enter the lower pole calices. Accordingly, we measured the change in the lower pole infundibulopelvic (LIP) angle when the patient's position was varied (i.e., prone, supine, head down) during intravenous urography (IVU).

PATIENTS AND METHODS

The LIP angle was measured in 20 right and 26 left adult kidneys during an IVU with the patient in six different positions: supine level, supine 20 degrees head down, supine 45 degrees head up, prone level, prone 20 degrees head down, and prone 45 degrees head up. None of the patients had a history of renal surgery.

RESULTS

In all cases, the broadest angle of entry to the lower pole infundibulum was obtained with the patient in a prone position and 20 degrees head down.

CONCLUSIONS

The LIP angle broadens when the patient lies in a prone 20 degrees head down position. This maneuver could improve the surgeon's ability to access the lower pole calices when performing flexible ureteronephroscopy.

Technique and complications of percutaneous nephroscopy: experience with 557 patients in the supine position

PURPOSE

Percutaneous nephroscopy is usually performed with the patient prone, which is uncomfortable for the patient and does not prevent damage to the colon. We assess the possibility of performing percutaneous nephroscopy using local anesthesia with the patient supine, and evaluate the advantages and complications.

MATERIALS AND METHODS

A total of 557 consecutive percutaneous nephroscopies were attempted in 221 men and 242 women in the supine position. Patient age ranged from 8 to 87 years (mean 55.1). Patients are supine with a 3 l. serum bag below the ipsilateral flank. We catheterize the affected uretheral meatus with a 5F catheter through a flexible cystoscope. The tract is infiltrated with local anesthesia. The skin is punctured in the posterior axillary line which corresponds to approximately 1 cm. above the bag. We use an Alken set to dilate the tract to 30F, which is the size of the Amplatz sheath we commonly use.

RESULTS

Nephroscopy was performed in 519 cases (93.1%). Mean operation time was 85 minutes (range 15 to 240). Serious bleeding occurred in 3 cases. The colon was never damaged in patients treated in the supine position.

CONCLUSIONS

Percutaneous nephroscopy using local anesthesia with the patient supine is safe and easy. According to our experience the advantages in comfort to the patient and feasibility to the surgeon justify its use.

Blunt renal trauma in childhood. Features indicating severe injury

The clinical presentation of children with blunt renal trauma may differ from that of adults. The clinical features at presentation of 50 consecutive children (20 severe injuries, no pedicle injuries) admitted over a period of almost 8 years were reviewed to determine if there were clinical clues to major renal trauma in childhood. Gross haematuria and low haematocrit were the most helpful factors at the time of presentation and correlated well with severe renal injury. Hypotension was seen in 4 patients and only 1 had severe renal trauma. Suspicion of a major renal injury should be high when there is gross haematuria or a low haematocrit. In this study only 1 of 20 patients with major renal injury demonstrated clinical signs of shock. Unlike adults, hypotension does not appear to be a reliable indicator of the severity of renal injury in children and diagnostic evaluation should not be reserved only for those in shock.

Changing surgical aspects of urinary stone disease

Surgical management of urinary calculous disease has changed dramatically in the past decade. The development of percutaneous nephrostomy techniques has allowed new access to upper tract stones. Percutaneous removal of large calculi was made possible by the development of ultrasonic and electrohydraulic lithotripsy. All upper tract calculi can now be removed in 70 to 100 per cent of cases with minimal complications. Nephrostolithotomy has reduced transfusion rates and hospitalization costs and has markedly shortened convalescence periods compared with open surgery. Ureteroscopy followed nephrostolithotomy as advanced fiberoptic technology allowed the development of the small-caliber instruments required for this procedure. With experience, successful stone retrieval has occurred in 90 per cent or more of cases, again with minimal complications. As nephrostolithotomy and ureteroscopy have become available, the subspecialty of endourology has emerged and significantly changed the management of urinary tract calculi. Perhaps the most significant advance in stone therapy has been the design and implementation of extracorporeal shock wave lithotripsy. With this noninvasive technique, most renal and proximal ureteral calculi can be effectively treated with minimal morbidity and convalescence. Research in lithotripter design is continuing, with more advanced and effective machines on the horizon. The applicability of extracorporeal therapy for the treatment of biliary tract calculi is currently under investigation. Finally, one should not disparage medical therapy for recurrent nephrolithiasis. A comprehensive metabolic evaluation combined with selective medical therapy provides almost complete relief from recurrent stone formation and makes medical therapy an integral component of treating the patient with renal or ureteral calculi.