[Clinical evaluation of spontaneous peripelvic extravasation]

We herein report 10 patients with spontaneous peripelvic extravasation. They were 7 males and 3 females, ranging in age from 39 to 78 years old. The spontaneous peripelvic extravasation were caused by ureteral stones in 6 patients, and by invasion of malignant tumors in 4 patients (2 gastric cancer, 1 prostatic cancer, 1 uterine cancer). In all patients with ureteral stones, the extravasation disappeared following conservative therapy or double J stent placement. In the cases of malignant tumors, nephrostomy or double J stent placement were needed for treatment of the extravasation and their prognosis were very poor.

[Two patients with emphysematous pyelonephritis]

A 55-year-old man with diabetes mellitus was sick with shivering, abdominal pain and Escherichia coli in blood and urine cultures; a 40-year-old woman with asthmatic bronchitis had abdominal pain and anaemia. Both had renal dysfunction and the CT scan showed hydronephrosis with a perirenal inflammatory infiltrate and gas in the right and left renal pelvis, respectively. The man had a difficult recovery after treatment with antibiotics and percutaneous drainage. In the woman, a calculus obstructed the pyelo-ureteral passage; the resected kidney contained a squamous cell carcinoma. She was operated, received chemotherapy and recovered. Emphysematous pyelonephritis is a rare, severe disease. Percutaneous drainage and, if necessary, nephrectomy are paramount in the treatment. The condition is observed mostly in patients with diabetes mellitus or obstruction of the urinary tract.

Percutaneous nephrolithotripsy in ectopic kidneys

BACKGROUND

Percutaneous nephrolithotomy (PCNL), although an accepted treatment modality in anatomically normal kidneys, is still not universally performed for calculi in pelvic ectopic kidneys. Fear of injury to abdominal viscera makes it a technically challenging procedure.

PATIENTS AND METHODS

We have performed PCNL in nine patients with calculi in pelvic ectopic kidneys. Technical factors which made this procedure safe include ultrasound-guided puncture, use of a mature tract or an Amplatz sheath, routine postoperative double-J stenting, and nephrostogram prior to nephrostomy tube removal.

RESULTS

Complete stone clearance was achieved in all cases. Six patients were treated in a single stage, while three patients required two stages. Seven patients needed only one tract, and two needed two tracts. No notable complications were encountered. The average hospital stay was 5.2 days.

CONCLUSION

With proper precautions and meticulous technique, PCNL is a safe and effective modality to treat calculi in pelvic ectopic kidney.

Ultrasound-guided drainage of perirenal and periureteral urine collections

Thirty patients with perirenal and periureteral collections were evaluated. The reasons for these collections were after open surgery on the kidney in 11, open surgery on the ureter in 10, percutaneous nephrostolithotomy in 2, after renal transplantation in 5, and after ureteroscopy in 2. The presenting symptoms and signs included flank pain in 12, urine leakage in 5, fever in 5, masses in the iliac fossa in 5, and flank mass in 3. Ultrasound-guided single-step drainage of these collections was done using 10-12 F catheters. Ultrasound-guided single-step percutaneous nephrostomy (PCN) was done prior to drainage of the collection in seven patients in whom ultrasound revealed back pressure changes in their renal units. Pigtail catheters (7-10 F) were used for PCN. The aspirated fluid was clear urine in 12 cases and turbid in 18. The amount of fluid drained ranged from 150-500 mL immediately after the procedure. We used color Doppler sonography to map the site of puncture. No complications were encountered after drainage. The period of drainage varied from 1 week to 37 days. Further intervention was needed in 12 cases due to development of ureteric stricture in 7, prolonged leakage in 3 (one after transplantation, one after ureterocolic anastomosis, and one after ureterolithotomy), and residual stones in 2. Double-J stenting was done in four cases. We conclude that ultrasound-guided drainage of perirenal and periureteral collections is a safe, rapid, and easy method of treatment and should eliminate the need for exploration to drain these collections. Whenever backpressure exists in the renal unit, ultrasound-guided PCN should be done prior to drainage of the collection.

[Anterograde insertion of ureteral catheter]

We report twenty-four patients with urinary obstruction, in which twenty-seven antegrade ureteral stent (double J) insertions were attempted (in six patients the obstruction was bilateral and in three other patients we failed). In all of them access to the urinary tract was through a nephrostomy catheter, in seventeen cases we proceeded to insert the antegrade catheter immediately after percutaneous nephrostomy and in ten remaining cases we achieved in a second try after carrying nephrostomy and failing a conventional retrograde approach to ureteral stent insertion. We got a 90-per cent success rate. A case of perirrenal hematoma occurred after applying a nephrostomy. It was the only relevant complication. In conclusion we consider that the antegrade ureteral stent insertion is a good alternative when, under several circumstances, the conventional retrograde insertion fails.

Augmentation ureterocystoplasty with ipsilateral renal preservation in the management of patients with compromised renal function secondary to dysfunctional voiding

We evaluated the role of ureterocystoplasty with ipsilateral renal preservation in the management of patients with neurovesical dysfunction and impaired renal function. The procedure was carried out on 6 patients with a mean age of 8.5 years. All patients had vesicoureteric reflux (VUR) secondary to neuropathic bladders, recurrent urinary tract infections, day time incontinence, impaired and deteriorating renal function. All patients were followed up with a mean of 22.5 months (range 6-30). Renal function stabilized in 4 patients and improved in 2 patients. Adequate urinary bladder capacity was achieved in all patients. Bladder volume increased from a mean of 210+/-71 to 382+/-66, this increase was statistically significant (p<0.001). All patients were dry by day including the children who at presentation were in diapers. We conclude that the results of this operative intervention are satisfactory and promising in the management of this difficult group of patients while avoiding the side effects of enterocystoplasty procedures.

Interventional uroradiologic procedures performed using gadodiamide as an alternative to iodinated contrast material

Three patients with either a history of severe allergic reactions to iodinated contrast or marked renal insufficiency underwent interventional uroradiologic procedures using full-strength gadodiamide (Gd) as a contrast agent in place of iodinated contrast material. The procedures were percutaneous access for nephrostolithotomy, antegrade pyelography with placement of a nephroureteral stent, and a diagnostic nephrostogram with exchange of a nephroureteral stent. Gd was visualized fluoroscopically and produced satisfactory digital radiographs without allergic reaction or worsening renal function. Gd can be useful in guiding interventional uroradiologic procedures when iodinated contrast material is contraindicated.

Medically resistant neonatal hypertension: revisiting the surgical causes

OBJECTIVE

To present the importance of searching for the surgical causes of pharmacologically resistant hypertension in the neonatal population.

STUDY DESIGN

A case report and discussion are provided.

RESULTS

Severe hypertension in the neonatal period is uncommon and almost always has a secondary cause. Although a majority of hypertensive neonates can be successfully managed with medical therapy, some cases are resistant to pharmacological treatment. We report three hypertensive neonates who failed to respond to intensive multidrug therapy. This led to further evaluation and identification of obstructive uropathies in two neonates and renovascular disease that necessitated surgical intervention. Subsequently, all patients had prompt resolution of hypertension and normalization of renal function. All are now off antihypertensive medications and have normal renal function at 12 months of follow-up.

CONCLUSION

Our report exemplifies the importance of the consideration of surgical etiologies for differential diagnosis in neonates with severe hypertension that is unresponsive to pharmacological therapy. Early diagnosis and prudent management of these etiologies reduce morbidity and mortality and preserve of renal function.

Percutaneous nephrolithotomy in the pediatric population

PURPOSE

Percutaneous nephrolithotomy is an established technique used in children with renal calculi. We review our experience with percutaneous nephrolithotomy for treating nephrolithiasis in childhood.

MATERIALS AND METHODS

We retrospectively reviewed the records of children who underwent percutaneous nephrolithotomy procedures for renal calculi from 1985 to 1996. Antegrade percutaneous access was obtained in all patients and the tract was dilated to 24F. Grasper forceps, ultrasound and/or electrohydraulic lithotripsy was used to remove and disintegrate stones. In all patients a nephrostomy tube was placed intraoperatively, and a plain abdominal x-ray and nephrostogram were done postoperatively. The nephrostomy tube was removed after ensuring free drainage down the ureter and no untoward effects from clamping. Complete anatomical and metabolic evaluation was performed in all cases. Patients were followed 2 to 6 weeks, and 3 and 6 months postoperatively with a plain abdominal x-ray and excretory urography or renal ultrasound.

RESULTS

In 5 boys and 3 girls (9 renal units) 4 to 11 years old (mean age 6.4) a total of 10 percutaneous nephrolithotomy procedures were performed. At presentation 6 children had flank and/or abdominal pain, 5 gross hematuria and 3 urinary tract infection. Three patients had associated metabolic abnormalities. One patient with a staghorn calculus had hydronephrosis and multiple infundibular stenoses. No underlying urological anatomical abnormalities were noted in the remaining cases. Four renal units that were obstructed at presentation required initial nephrostomy tube insertion. Average operative time was 131.8 minutes (range 58 to 240). An 87.5% stone-free rate was achieved using percutaneous nephrolithotomy monotherapy. Percutaneous nephrolithotomy was not successful for eradicating a staghorn stone in 1 patient. Hypothermia developed in 2 patients in whom operative time exceeded 150 minutes. No blood transfusions were required.

CONCLUSIONS

Percutaneous nephrolithotomy is safe and effective in children, and should be considered a viable management option. However, staghorn calculi may require alternative management, particularly in the setting of underlying anatomical abnormalities. Children with renal calculi should undergo a complete anatomical and metabolic assessment with the institution of medical therapy, as appropriate.

Percutaneous management of renal calculi: experience with percutaneous nephrolithotomy in 60 children

PURPOSE

We report our experience with percutaneous nephrolithotomy in a pediatric population in which primary as well as recurrent stone episodes are frequent and the need for less invasive procedures is imperative.

MATERIALS AND METHODS

Percutaneous nephrolithotomy was performed in 60 children 3 to 13 years old (average age 6), including 44 boys (73.3%) and 16 girls (26.7%). There was a single obstructing renal calculus in 43 patients, while 17 had multiple calculi. The procedure was performed in 1 stage in 49 patients, and it was staged with preliminary nephrostomy in 11 who presented with calculous anuria and elevated serum creatinine. Normal saline was used as an irrigant and perioperatively serum electrolytes were measured to monitor fluid absorption in 18 patients. Stones were extracted intact from 40 patients (66.6%) and ultrasonic lithotripsy was performed in 20 (33.3%).

RESULTS

Of the 60 patients 50 (83.3%) were rendered stone-free at 1 session. Incomplete stone clearance at 1 session was due to intraoperative bleeding requiring blood transfusion, extravasation, multiple stones that were inaccessible via 1 tract, displacement of stone fragments into an inaccessible calix and insignificant residual fragments less than 3 mm. in 2 cases each. During followup of 3 months to 6 years (average 1 year) no late complications were noted.

CONCLUSIONS

Percutaneous nephrolithotomy is a safe and relatively efficacious mode of managing pediatric renal calculi. Although higher success rates are achieved in adults, caution should be exercised in children, in whom diligent attempts at stone clearance in 1 session may be made at the expense of safety.

[The combined treatment of calculous pyelonephritis with the use of perfusion of the kidney cavitary system with the preparation Palisan in the postoperative period]

Results are submitted of use of perfusion of the kidney cavitary system with the drug Palisan in the postoperative period in a multimodality treatment of calculous pyelonephritis. On the basis of bacteriological investigations a high efficacy of the drug in carrying out perfusion of the caliceal-and-pelvic system in treating the inflammatory process in the kidneys has been ascertained. An optimal methodical approach to the carrying out of perfusion has been developed. Also emphasized in the paper is value of perfusion of the kidney cavitary system in metaphylaxis of urolithiasis.

[Role of flexible mini-ureteroscopes in diseases of the upper urinary tract]

INTRODUCTION

The management of upper urinary tract disease has been improved by miniaturization of endoscopes. Our objective was to assess the value of flexible mini-ureteroscopes for the diagnosis and treatment of upper urinary tract lesions.

PATIENTS AND METHODS

33 consecutive patients (mean age: 49 +/- 16 years; 23 men) underwent first-line flexible ureteroscopy for upper urinary tract disease, consisting of: stones: 21, filling defect: 6, stenosis: 3, haematuria: 2, positive cytology: 1 and situated in the kidney + renal pelvis: 14 or ureter: 19. The 21 stones were situated in: the calyx: 5, renal pelvis: 1, lumbar ureter: 8, iliac ureter: 3, pelvic ureter: 4. Their mean dimensions were 9.7 +/- 4 x 5.3 +/- 2.3 mm. Previous treatment had failed for 13 stones. There 7.5 F flexible ureteroscopes of various brands were used.

RESULTS

All patients were operated under general anaesthesia. Antegrade ureteroscopy was performed in 2 patients. Advancement of the ureteroscope was considered to be difficult in 5 cases, including the 2 antegrade cases. 13 stones were fragmented by hydroelectric waves. The mean duration of ureteroscopy was 40 +/- 15 min. The mean hospital stay was 2.8 +/- 1 days. There was no intraoperative or perioperative morbidity. Ureteroscopy was considered to be successful in 27 cases (82%) and a failure in 6 cases: fragmentation: 3 and progression: 3. Fifteen patients were reviewed after more than one month (3 +/- 2 months) with no morbidity.

CONCLUSION

Ureteroscopy with flexible mini-ureteroscopes is an effective, reproducible and minimally traumatic diagnostic and therapeutic technique. It is particularly useful for lesions situated above the iliac vessels and is indicated for diagnostic assessment and stones, but also upper tract malformations and strictures.

Strategies for managing upper tract calculi in young children

PURPOSE

Pediatric urolithiasis is relatively uncommon and there is little information on the application of modern surgical procedures in young children. We present a single center experience with the surgical management of upper tract calculi in this age group.

MATERIALS AND METHODS

We reviewed presentation, co-morbidity, treatment, outcome and complications in all prepubertal patients who required surgical treatment for ureteral or renal calculi during a 4-year period. The series consists of 24 girls and 17 boys 17 months to 14 years old (mean age 7.5 years). A total of 26 children were anatomically normal, and 4 had myelomeningocele, 4 had ureteropelvic junction obstruction (in a pelvic kidney in 1), 2 had cloacal anomalies, 2 had vesicoureteral reflux, and 1 each had nonrefluxing megaureter, orthotopic ureterocele and a functioning renal transplant.

RESULTS

Extracorporeal shock wave lithotripsy was performed in 24 patients. Stents or nephrostomy tubes were only used in the 4 patients who presented with pyonephrosis. Of the 41 cases 17 were rendered stone-free, 3 had a decreased stone burden and 4 were failures. Ureteroscopic extraction of distal ureteral calculi was successful in 11 of 12 children, of whom the youngest was 2.5 years old. No child had postoperative infection or evidence of ureteral obstruction. Stent placement facilitated stone passage or dissolution in 2 patients, a renal calculus was percutaneously extracted in 2 and 7 required open surgery, mostly for correcting simultaneous anatomical abnormalities or after minimally invasive surgery failed. Some metabolic abnormality was detected in 80% of the children tested.

CONCLUSIONS

The surgical management of upper urinary tract calculi in young children parallels that in adults. Minimally invasive surgical methods may be safely used even in young infants. Most children do not need elective stenting before lithotripsy. Open procedures are still required in 17% of cases. The majority of children have definable metabolic abnormalities.

Percutaneous stone removal in horseshoe kidneys

PURPOSE

We review our experience with percutaneous nephrolithotomy for stones in horseshoe kidneys when extracorporeal shock wave lithotripsy was unsuccessful or inappropriate because of stone burden.

MATERIALS AND METHODS

Stone burden, nephrostomy and percutaneous surgical techniques, and clinical outcome of 12 consecutive patients undergoing percutaneous nephrolithotomy for calculi in horseshoe kidneys between 1988 and 1997 were reviewed.

RESULTS

Complete stone removal was achieved by percutaneous methods alone in 9 patients (75%). More than 1 nephrostomy tract was required in 5 patients and additional intraoperative nephrostomies were necessary in 4. Flexible nephroscopy was essential in achieving complete stone removal in 9 of 11 patients (82%). Second look procedures for stone removal were required in 3 patients. No sepsis occurred and no transfusions were needed.

CONCLUSIONS

Percutaneous nephrolithotomy is a safe and effective method of stone removal in patients with calculi in horseshoe kidneys. Multiple nephrostomy tracts, the use of flexible nephroscopy and second look procedures may be necessary to achieve optimum stone removal.

Strategies for managing upper tract calculi in young children

PURPOSE

Pediatric urolithiasis is relatively uncommon and there is little information on the application of modern surgical procedures in young children. We present a single center experience with the surgical management of upper tract calculi in this age group.

MATERIALS AND METHODS

We reviewed presentation, co-morbidity, treatment, outcome and complications in all prepubertal patients who required surgical treatment for ureteral or renal calculi during a 4-year period. The series consists of 24 girls and 17 boys 17 months to 14 years old (mean age 7.5 years). A total of 26 children were anatomically normal, and 4 had myelomeningocele, 4 had ureteropelvic junction obstruction (in a pelvic kidney in 1), 2 had cloacal anomalies, 2 had vesicoureteral reflux, and 1 each had nonrefluxing megaureter, orthotopic ureterocele and a functioning renal transplant.

RESULTS

Extracorporeal shock wave lithotripsy was performed in 24 patients. Stents or nephrostomy tubes were only used in the 4 patients who presented with pyonephrosis. Of the 41 cases 17 were rendered stone-free, 3 had a decreased stone burden and 4 were failures. Ureteroscopic extraction of distal ureteral calculi was successful in 11 of 12 children, of whom the youngest was 2.5 years old. No child had postoperative infection or evidence of ureteral obstruction. Stent placement facilitated stone passage or dissolution in 2 patients, a renal calculus was percutaneously extracted in 2 and 7 required open surgery, mostly for correcting simultaneous anatomical abnormalities or after minimally invasive surgery failed. Some metabolic abnormality was detected in 80% of the children tested.

CONCLUSIONS

The surgical management of upper urinary tract calculi in young children parallels that in adults. Minimally invasive surgical methods may be safely used even in young infants. Most children do not need elective stenting before lithotripsy. Open procedures are still required in 17% of cases. The majority of children have definable metabolic abnormalities.

Long-term results of percutaneous endourologic management of renal infundibular stricture

PURPOSE

The long-term result of percutaneous endourologic management in the relief of infundibular stricture is not clear. We reviewed the long-term efficacy in our series of patients.

PATIENTS AND METHODS

Twenty-seven patients underwent percutaneous endourologic management between August 1990 and February 1996. This study included the 21 who could be followed for more than 2 years (mean 4.8 years). The causes of stricture were tuberculosis (N = 18; 86%) and stone (N = 3; 14%). We made a cold-knife incision in eight patients; the others underwent only dilation with fascial dilators from 20F to 30F. Success was defined as symptomatic improvement and radiographic resolution of obstruction.

RESULTS

The overall success rate was 76% (16 of 21). Seven of the eleven patients (64%) with concomitant ureteral stricture had a successful result. In the nine patients with multiple infundibular strictures, five procedure (56%) were successful. The success rates of the cold-knife or fascial dilator were 88% (7 of 8) and 69% (8 of 13), respectively. In the five patients in whom the procedure failed, ureteral stricture was associated in four and multiple infundibular strictures in four. All of them had tuberculous infundibular strictures. No significant difference in the success rate was observed according to the duration of indwelling catheter. There was no significant complication except pyelonephritis in four patients, which was controlled with conservative treatment.

CONCLUSIONS

Percutaneous endourologic management is an effective and safe procedure to treat renal infundibular stricture. Risk factors for failure are multiple infundibular strictures and concomitant ureteral stricture. If the procedure does fail, other treatments have not been compromised. Cold-knife incision seems to be more effective than dilation.

Autologous blood use in percutaneous nephrolithotomy

OBJECTIVES

Preoperative autologous blood (AUB) donation has decreased patient exposure to allogenic blood (ALB) products and associated infectious risk. The risk of contracting hepatitis C and human immunodeficiency virus is 1 in 103,000 and 1 in 678,000, respectively, after receiving 1 U ALB. Elective surgical procedures require surgeons to offer preoperative AUB donation in California. Unused AUB is discarded. We report our use of AUB obtained for percutaneous nephrolithotomy.

METHODS

A retrospective study of 144 consecutive patients who underwent 193 percutaneous nephrolithotomies between January 1994 and April 1998 at one of four teaching hospitals at the University of California, San Francisco was performed. Preoperative AUB donation, transfusion rates, hemoglobin levels, blood use, and costs were analyzed.

RESULTS

Ninety-six units of blood were collected from 63 patients (44%) and were available for 70 procedures (36%). The overall transfusion rate per procedure was 7%, with 13 patients receiving a total of 24 U, 7 AUB and 17 ALB. Eighty-nine units (92.7%) of AUB were discarded, and the transfusion rate in donors and nondonors was similar. There was no significant difference in preoperative hemoglobin or operative blood loss between donors and nondonors. The 13 transfused patients had a lower preoperative hemoglobin ( 11.5 versus 12.8 g/dL; P = 0.029) and higher operative blood loss as measured by hemoglobin level (3.2 versus 1.6 g/dL; P <0.001). Blood bank charges for ALB and AUB were $ 119/U and $244 to $498/U, respectively, depending on transportation and thawing charges.

CONCLUSIONS

Routine preoperative blood donation adds substantial cost for minimal benefit, given the low infectious risk of ALB and the two- to fourfold higher cost of AUB. In our series, women had an increased incidence of blood transfusion compared with men. AUB donation may provide peace of mind but is rarely used and is discarded 93% of the time.

Radio-contrast enhancement of a urinary tract calculus

We report the case of a woman who presented with obstruction and urosepsis of her left kidney secondary to small cystine calculi. The calculi could not be seen on initial plain abdominal X-ray. However, following percutaneous nephrostogram the calculi became more radio-dense and visible on later X-rays. Experimental enhancement of calculi has been described before but not in man. We presume that the contrast medium was adsorbed by the calculus to increase the radio-density. Further investigation of this phenomenon could prove useful in the management of complex radiolucent calculi.

Percutaneous nephrostomy as adjunct management in advanced upper urinary tract infection

OBJECTIVES

To determine by retrospective review of 315 percutaneous nephrostomies, performed for pyonephrosis, whether this intervention has major clinical advantages.

METHODS

From 1977 to 1996, under the direct supervision of the senior author of this report (E.K.L.), at seven hospital sites, 315 patients (181 males, 134 females; 17 to 88 years of age) were treated with percutaneous nephrostomy and antibiotic therapy for infected hydronephrosis.

RESULTS

Additional or disparate pathogens were identified in 116 (36.8%) of 315 patients, leading to a clinically significant change in, or addition of, antibiotics and/or antifungal agents in 84 (73%) of 116. Most notably, we often found a clinically important disparity between the results of cultures obtained from the nephrostomy and those obtained from bladder-urine specimens.

CONCLUSIONS

This retrospective review confirms previously reported advantages of percutaneous upper urinary tract drainage as a potentially life-saving adjunct in the treatment of pyonephrosis. Several case studies highlight the advantage of this maneuver in difficult cases involving obstruction due to extensive fungus or debris. In particular, our review focuses attention on the clinically important insight that urine cultures from percutaneous nephrostomy drainage often identify pathogens that differ from those detected in concurrent bladder cultures.

Bladder agenesis with urometrocolpos

A 20-day-old female presented in acute renal failure with an absent bladder and vaginal atresia. The right ureter opened into the uterus, resulting in a urometrocolpos, and the left ureter opened through a stenotic opening into the introitus. The literature is reviewed for reported cases and the embryo-pathology of bladder agenesis is discussed.

Sensitivity of noncontrast helical computerized tomography and plain film radiography compared to flexible nephroscopy for detecting residual fragments after percutaneous nephrostolithotomy

PURPOSE

We prospectively compared plain film radiography and noncontrast, thin cut helical computerized tomography (CT) to flexible nephroscopy for detecting residual stones after percutaneous nephrostolithotomy.

MATERIALS AND METHODS

We prospectively evaluated 36 patients (41 renal units) undergoing percutaneous nephrostolithotomy for large (greater than 3 cm., 23 renal units) or staghorn (18 renal units) calculi. All patients underwent postoperative imaging with plain film of the kidneys, ureters and bladder and noncontrast helical CT, and flexible nephroscopy on postoperative day 2 or 3. The size and location of residual fragments determined radiographically and identified by flexible nephroscopy were compared.

RESULTS

Plain film radiography and CT detected an average of 0.7 and 3.4 stones per renal unit, respectively. With a mean operating time plus or minus standard deviation of 77.3+/-35 minutes and a mean fluoroscopy time of 7.6+/-6.7 minutes, an average of 2.3 stones per renal unit were retrieved at flexible nephroscopy. In 90.2% of renal units all calices could be directly inspected. The sensitivity and specificity were 46% and 82% for plain film radiography, and 100% and 62% for CT, respectively, using flexible nephroscopy as the gold standard for detecting residual stones. The overall stone-free rate after flexible nephroscopy was 92.6%. The cost of this procedure is $5,625.13 compared to $220 for CT, including the interpretation fee, at our institution.

CONCLUSIONS

Selective use of flexible nephroscopy after percutaneous nephrostolithotomy based on positive CT findings will avoid an unnecessary operation in 20% of patients. The rate of unnecessary procedures is 32% if all patients undergo flexible nephroscopy, regardless of radiographic findings. At our institution this strategy will result in a cost savings of $109,687 per 100 patients.