Resonance metallic stents do not effectively relieve extrinsic ureteral compression in pediatric patients

BACKGROUND AND PURPOSE

Use of metallic stents (Resonance) has been reported in the literature to be effective in relieving extrinsic obstruction in adults. Successful patency rates have been reported to be around 83.3%. The use of Resonance stents in children has not been reported. We present our experience with these stents in addressing extrinsic ureteral obstruction in the pediatric population.

PATIENTS AND METHODS

We identified two patients who underwent placement of Resonance stents for extrinsic compression at the Children's Hospital of the University of Pittsburgh Medical Center. The first patient is a 12-year-old girl with a solitary left kidney who had a diagnosis of pelvic rhabdomyosarcoma; she was treated with surgery followed by adjuvant chemoradiation. Two years post-treatment, worsening renal function secondary to ureteral strictures developed. The second patient is a 14-year-old girl with a history of Gardner syndrome. Recurrent desmoid tumors developed in her pelvis and retroperitoneum that led to right ureteral obstruction, necessitating a nephrostomy tube.

RESULTS

Both patients underwent successful technical placement of a Resonance stent. The time to failure for patient 1 was 3 months and for patient 2, 3 weeks. The first patient presented to the emergency department 3 months poststent in renal failure with a creatinine level of 13.7 mg/dL. This necessitated nephrostomy tube placement and hemodialysis. Ultimately, she needed an ileal ureter to preserve renal function. She is off hemodialysis and has a creatinine level of 2.2 mg/dL.The second patient, recurrent episodes of pyelonephritis, worsening hydronephrosis, and flank pain developed with just the Resonance stent in place. It was elected to remove the Resonance stent and replace the nephrostomy tube. She needed extensive ureterolysis, a right subtotal ureterectomy with a right to left ureteroureterostomy.

CONCLUSION

We did not find the use of these stents to be effective in children. The time to failure was significantly shorter in children than those reported in the literature for adults.

Advances in the surgical pediatric urologic armamentarium

The surgical armamentarium of the pediatric urologist has changed greatly in the past 2 decades on account of new technology and careful adaptation of minimally invasive techniques in children. Conventional laparoscopy, robotic-assisted laparoscopy, laparoendoscopic single-site surgery, and endourologic surgery have, to varying degrees, provided new approaches to urologic surgery in the pediatric population. This article reviews the technology and adaptations behind these recent advances as well as their current applications in management of urologic disease in children.

Pediatric laparoscopic and robot-assisted laparoscopic surgery: technical considerations

Laparoscopy has become an effective modality for the treatment of many pediatric urologic conditions that need both extirpative and reconstructive techniques. Laparoscopic procedures for urologic diseases in children, such as pyeloplasty, orchiopexy, nephrectomy, and bladder augmentation, have proven to be safe and effective with outcomes comparable to those of open techniques. Given the steep learning curve and technical difficulty of laparoscopic surgery, robot-assisted laparoscopic surgery (RAS) is increasingly being adopted in pediatric patients worldwide. Anything that can be performed laparoscopically in adults can be extended into pediatric practice with minor technical refinements. We review the role of laparoscopic and RAS in pediatric urology and provide technical considerations necessary to perform minimally invasive surgery successfully.

Incidentally discovered capillary hemangioma of the prostate

We present the case of a 69-year-old male with incidentally discovered capillary hemangiomas at radical prostatectomy. Hemangiomas of genitourinary origin are extremely rare, typically benign vascular tumors. This finding represents the first reported hemangioma within a radical prostatectomy specimen.

The evolution of the endourologic management of pediatric stone disease

In the 1980s, the advent of shock wave lithotripsy (SWL) revolutionized pediatric stone management and is currently the procedure of choice in treating most upper tract calculi <1.5 cm in children. However, with miniaturization of instruments and refinement of surgical technique the management of pediatric stone disease has undergone a dramatic evolution over the past twenty years. In a growing number of centers, ureteroscopy (URS) is now being performed in cases that previously would have been treated with SWL or percutaneous nephrolithotomy (PCNL). PCNL has replaced open surgical techniques for the treatment of large stone burdens >2 cm with efficacy and complication rates similar to the adult population. Recent results of retrospective reviews of large single institution series demonstrate stone free and complication rates with URS comparable to PCNL and SWL but concerns remain with these techniques regarding renal development and damage to the pediatric urinary tract. Randomized controlled trials comparing the efficacy of SWL and URS for upper tract stone burden are needed to reach consensus regarding the most effective primary treatment modality in children. This report provides a comprehensive review of the literature evaluating the indications, techniques, complications, and efficacy of endourologic stone management in children.

Real-time tomographic reflection in facilitating percutaneous access to the renal collecting system

BACKGROUND AND PURPOSE

Real-time tomographic reflection is a novel technique that uses a geometrically fixed arrangement of a conventional ultrasound transducer, a transducer-incorporated monitor, and a half-silvered mirror. This device, dubbed the Sonic Flashlight, generates a virtual anatomically scaled image, obviating the need for a separate monitor. It may therefore facilitate invasive procedures, such as percutaneous access to the kidney. This proof-of-concept study assesses the feasibility of this technique for renal imaging and concomitant needle puncture guidance.

MATERIALS AND METHODS

In a swine model with induced hydronephrosis, the Sonic Flashlight was used to visualize and guide needle access to the renal pelvis. Passage of a 7-inch, 18-gauge spinal needle was performed. Entry into the collecting system was confirmed by the aspiration of urine.

RESULTS

The anechoic renal pelvis and hyperechoic needle tip could be seen with the Sonic Flashlight device. Successful access to the collecting system was obtained twice without dificulty. The sonographic image, appearing to emanate from the tip of the transducer, makes visualization and manipulation more intuitive. Furthermore, by placing the operator's eyes and hands in the same field as the sonogram, image-guided procedures are potentially easier to learn.

CONCLUSION

The relatively shallow depth of penetration of the current device limits its clinical usefulness. A new Sonic Flashlight with a greater depth of penetration is in development.

Management of urine leak after laparoscopic cyst decortication with retrograde endoscopic fibrin glue application and ureteral stent placement

Urine leakage is an uncommon complication after renal cyst decortication that typically resolves with adequate drainage. With prolonged large volume urine leakage from a perinephric drain, however, consideration for open surgical repair must be taken into account. We present the successful management of persistent urine leakage after laparoscopic cyst decortication with endoscopic retrograde fibrin glue injection and ureteral stent placement.

Contemporary surgical management of pediatric urolithiasis

With miniaturization of instruments and refinement of surgical technique, the management of pediatric stone disease has undergone a dramatic evolution. While shock wave lithotripsy (SWL) is still commonly used to treat upper tract calculi, the use of ureteroscopy (URS) has dramatically increased and is now the procedure of choice for upper tract stone burdens less than 1.5cm at centers with significant experience. Percutaneous nephrolithotomy (PCNL) has replaced open surgical techniques for the treatment of large stone burdens greater than 2cm, with efficacy and complication rates similar to the adult population. Large institutional series demonstrate comparable stone-free and complication rates with SWL, URS, and PCNL, but concerns remain with these techniques regarding renal development and damage to the pediatric urinary tract. Randomized controlled trials comparing the efficacy of SWL and URS for upper tract stone burdens are needed to reach consensus regarding the most effective primary treatment modality in children.

Evolution of laparoscopy in pediatric urology

The use of laparoscopy has evolved over the last 30 years, particularly in the last decade, from merely extirpative or diagnostic procedures to intricate reconstructive procedures on the major genitourinary organs. The development of laparoscopy as a method of treating urological problems has progressed more slowly in children compared with adults; perhaps due to the availability of miniaturized technology, the steep learning curve and the high success of traditional open surgery. This article seeks to provide a comprehensive review of the evolution of laparoscopy from its inception to its present-day applications in the field of pediatric urology, including the current indications and results of various laparoscopic procedures.

Needle steering system using duty-cycled rotation for percutaneous kidney access

The authors present ongoing work on the use of a variable curvature flexible needle steering system to gain percutaneous access to the kidney for medical interventions. A nonlinear control law is introduced which drives the needle to track a predetermined planar path using a steering approach based on duty-cycled rotation during insertion. Renal access is performed in simulation and tested in vitro in a tissue phantom to validate the proposed control method.

Endourological management of pediatric stone disease: present status

PURPOSE

The incidence of nephrolithiasis in the pediatric population has been steadily increasing. The miniaturization of endoscopic instruments and improvement in imaging modalities have facilitated safe and effective endourological treatment in this patient population. We reviewed the current status of pediatric stone disease management.

MATERIALS AND METHODS

A comprehensive literature review was performed using MEDLINE/PubMed to evaluate the indications, techniques, complications and efficacy of endourological stone management in children.

RESULTS

In the 1980s shock wave lithotripsy revolutionized stone management in children, becoming the procedure of choice for treating upper tract calculi less than 1.5 cm. Percutaneous nephrolithotomy has replaced open surgical techniques for the treatment of stone burdens greater than 1.5 cm with efficacy and complication rates mirroring those in the adult population. However, at an increasing number of centers ureteroscopy is now being performed in cases that previously would have been treated with shock wave lithotripsy or percutaneous nephrolithotomy. Results from recent retrospective series demonstrate that stone-free rates and complication rates with ureteroscopy are comparable to percutaneous nephrolithotomy and shock wave lithotripsy. Although concerns remain with all endoscopic techniques in children regarding damage to the urinary tract and renal development, neither short-term nor long-term adverse effects have been consistently reported.

CONCLUSIONS

Shock wave lithotripsy, percutaneous nephrolithotomy and ureteroscopy are highly effective endourological techniques to treat stone disease in the pediatric population. A lack of prospective randomized trials comparing treatment modalities coupled with a vast disparity in the access to resources worldwide continues to individualize rather than standardize stone treatment in children.

Totally bloodless percutaneous renal surgery

INTRODUCTION

We evaluated the feasibility of intraoperative transarterial balloon occlusion of renal artery as a novel technique to reduce blood loss in high-risk patients undergoing complex percutaneous renal surgery (PRS).

METHODS

Four patients (staghorn calculi: n=2, renal pelvis TCC: n=1, ureteropelvic junction obstruction: n=1) underwent transfemoral arteriography prior to PRS. The renal artery was identified and an occluding balloon was inflated in the main renal artery. The kidney was intermittently allowed to perfuse with heparinized saline. Percutaneous renal access was obtained under fluoroscopic guidance by the urologist. Multiple tracts were established as needed to perform the procedure. The arterial occluding balloon was taken down at the completion of PRS and renal angiography repeated through the established angiographic catheter to identify any vascular injury.

RESULTS

Subjective improved visualization was attributed to decreased bleeding. Blood loss was less than 500 cc. Post-PRS intraoperative angiography revealed no active bleeding vessels requiring embolization. Two of the four patients presented with delayed renal hemorrhage over 10 days later requiring angiography and selective embolization with cessation of bleeding. All vascular abnormalities identified on repeat angiogram were not present on immediate post-PRS angiography.

CONCLUSIONS

Intraoperative balloon occlusion of renal artery is feasible and safe in patients undergoing complex PRS. Vascular control improves intraoperative endoscopic visibility while reducing intraoperative blood loss in patients at high risk for bleeding. However, these patients can still be at risk for delayed hemorrhage as iatrogenic vascular abnormalities, which can cause bleeding, can take time to develop and not be evident immediately post PRS.