Intra- and inter-observer variability of functional MR urography (fMRU) assessment in children.

BACKGROUND: Functional MR urography (fMRU) provides comprehensive functional data that can be subject to variability. To interpret the results of fMRU, it is essential to know the intra- and inter-observer variability of the measured parameters. OBJECTIVE: To define the range of variability in fMRU, particularly that of the differential renal function based on volume (volumetric differential renal function) and Patlak differential renal function measurements in children. MATERIALS AND METHODS: We included 15 fMRU studies, 10 of non-duplicated and 5 of unilateral duplex kidneys. We recruited six observers with a range of fMRU experience, including two MRI technologists, one resident, one fellow, one pediatric radiologist and one pediatric urologist. The observers underwent intensive training in using the Children's Hospital of Philadelphia (CHOP)-fMRU freeware for analysis. They conducted the fMRU analysis on each case twice, at least 1 week apart. Mean and standard deviation were calculated for each set of absolute volume, absolute Patlak, volumetric differential renal function and Patlak differential renal function. We calculated the statistical significance of these deviations using the student's t-test. We also calculated interclass correlations for intra-observer and inter-observer agreement of both volume and Patlak measurements using SPSS software. RESULTS: Intra- and inter-observer variability did not differ significantly, measuring 6% and 4% for relative volume (volumetric differential renal function: P > 0.05) and 5% and 3% for relative function (Patlak differential renal function: P > 0.05). Absolute values of parameters showed more variability than the relative values. Intra- and inter-observer agreement was well above 0.90 (P < 0.001) for all volume measures except for duplex upper pole intra-observer measurements (0.80, P < 0.01). Intra- and inter-observer agreement for Patlak values were also above 0.90 (P < 0.001) except for duplex upper pole measurements, which were 0.54 (P = 0.13) and 0.81 (P < 0.01), respectively. CONCLUSION: Functional MRU analysis using CHOP-fMRU software is reproducible, with overall intra- and inter-observer variability rates of 5% for volumetric differential renal function and 4% for Patlak differential renal function. There was higher variability in volume and function measurements between upper and lower pole moieties of duplicated kidneys and for absolute volume and function values overall. A range of 45-55% for relative values of volumetric differential renal function and Patlak differential renal function could serve as the normal range.

Robotic surgery in pediatric urology.

Minimally invasive laparoscopic procedures for urological diseases in children have proven to be safe and effective, with outcomes comparable to open procedures. Technical advances, including improved instruments and high-definition cameras, have contributed to the expanded role of minimal invasive surgery (MIS) in children. The major drawback to laparoscopy has been the relatively steep learning curve due to the technical difficulties of suturing and the limitations of instrument dexterity and range of motion. Recently, robotic-assisted laparoscopic surgery (RAS) has gained popularity in both adult and pediatric urology. RAS has several advantages over conventional laparoscopic surgery, particularly in the improved exposure via magnified 3-dimensional view and simplification of suturing with the increased degree of freedom and movement of the robotic arm. This review discusses the role of RAS in pediatric urology and provides technical aspects of RAS in specific urologic procedures as well.

Morbidity and efficacy of ureteroscopic stone treatment in patients with neurogenic bladder.

PURPOSE: There is a lack of information on the safety and efficacy of ureteroscopy in the neurogenic bladder population. We hypothesized that ureteroscopy in patients with neurogenic bladder would be associated with an increased risk of complications and a lower stone clearance rate than in patients without neurological impairment. MATERIALS AND METHODS: We reviewed a local registry of patients with ICD-9 codes for urolithiasis between 2004 and 2012. The study cohort was assembled from all eligible patients with neurogenic bladder and a randomly selected control group that had undergone ureteroscopy. Statistical analysis of demographic variables and surgical outcomes was performed. Complications were classified according to the Clavien system. Clearance was defined by computerized tomography, renal/bladder ultrasound or direct ureterorenoscopy. RESULTS: Ureteroscopy was performed a total of 173 times in 127 controls and a total of 45 times in 20 patients with neurogenic bladder. There was no difference between presenting episodes by gender (p = 1.0), race (p = 0.654) or body mass index (p = 0.519). Bacteriuria was associated with the stone episode in 16.4% of controls and 67% of neurogenic bladder cases (p <0.001). Median operative time was significantly longer in those with neurogenic bladder (80.5 minutes, IQR 50-110.5 vs 52, IQR 33-78, p = 0.0003). The proportion of complications was significantly different (p = 0.013). Stones cleared in 86.6% of controls compared to 63% of neurogenic bladder cases (p = 0.004). CONCLUSIONS: Patients with neurogenic bladder have increased morbidity after ureteroscopy for upper tract calculi compared to neurologically unaffected controls. Infection has a role in this morbidity. The clearance rate is lower but the stone burden is more significant in those with neurogenic bladder.

Learning curve of robotic assisted pyeloplasty for pediatric urology fellows.

PURPOSE: Little is known about the learning curve of robotic surgery for surgeons in training. We hypothesized that pediatric urology fellows could attain proficiency in robotic pyeloplasty, defined as operative time equivalent to that of an experienced robotic surgeon, within the 2-year time frame of fellowship. MATERIALS AND METHODS: From 2006 to 2010 we performed a prospective cohort study of pediatric robotic pyeloplasty done by 4 pediatric urology fellows and 1 pediatric urology attending surgeon. We recorded operative times and surgical outcomes of the total of 20 consecutive robotic pyeloplasties performed by the 4 pediatric urology fellows (80 cases) and a random sample of 20 performed by the attending surgeon. Multivariate linear regression was used to determine the change in operative time for each case done by fellows and estimate the number of cases needed for fellows to achieve the median operative time of the attending pediatric urologist. RESULTS: Fellow operative time decreased at a constant average rate of 3.7 minutes per case (95% CI 3.0-4.3). Fellows were projected to achieve the median operative time of the attending surgeon after 37 cases. No operative complications or failed pyeloplasties occurred. CONCLUSIONS: The operative time for robotic pyeloplasty performed by fellows consistently decreased with cumulative surgical experience. These data can be used to help establish benchmarks of robotic pyeloplasty for pediatric urology, assuming appropriate exposure to robotics and adequate case volume.

Robotic surgery of the kidney and ureter in pediatric patients.

Robotic actuators have revolutionized surgery for urologic disorders in pediatric patients. Robotic procedures have become widely available for several different ablative and reconstructive operations in children. The success rates have paralleled those of open surgical techniques and provide the benefit of smaller incisions and less manipulation of tissue during the procedures. Robotics employs increased dexterity, better visualization, and less fatigue, allowing greater precision. We must continue to evolve with the ever-changing advancements in technology and take a keen interest in maintaining our skills to ensure excellent outcomes and patient safety.

Unilateral hypercalciuria: a stealth culprit in recurrent ipsilateral urolithiasis in children.

PURPOSE: Hypercalciuria is a risk factor for nephrolithiasis. We hypothesized that children with recurrent stones in 1 but not both kidneys and a normal 24-hour bladder urine calcium-to-creatinine ratio might exhibit isolated hypercalciuria of the affected kidney. MATERIALS AND METHODS: Patients 18 years or younger with symptomatic urolithiasis who had undergone ureteroscopic stone removal were included. All subjects underwent 24-hour bladder urinalysis. Subjects with an increased urine calcium-to-creatinine ratio from the 24-hour urine collection were excluded. The 4 subject cohorts defined were 1) single stone episode in 1 kidney, 2) single stone episode in both kidneys, 3) recurrent stone episodes on 1 side and 4) recurrent stone episodes on both sides. All urine collections were obtained at ureteroscopy. Urine was obtained from the bladder and from the renal pelvis of the kidney forming the stone. Spot urine calcium-to-creatinine ratio was determined from these samples. RESULTS: A total of 329 patients were included. Nine of 74 subjects (12%) with recurrent stone episodes on 1 side had increased spot urine calcium-to-creatinine ratio from the affected kidney. No patients in the other cohorts had increased spot urine calcium-to-creatinine ratio. Patients who formed recurrent stones in 1 kidney had increased spot urine calcium-to-creatinine ratio in the affected kidney vs other stone formers (ANOVA p <0.001). CONCLUSIONS: Unilateral hypercalciuria can occur in children with normal calcium levels in bladder urine. Unilateral hypercalciuria should be considered as a risk factor for nephrolithiasis in children with recurrent stone episodes in 1 kidney only.

Endoscopic management and the role of double stenting for primary obstructive megaureters.

PURPOSE: We determined the efficacy and potential complications of endoscopic incision and balloon dilation with double stenting for the treatment of primary obstructive megaureter in children. MATERIALS AND METHODS: We prospectively reviewed cases of primary obstructive megaureter requiring repair due to pyelonephritis, renal calculi and/or loss of renal function. A total of 17 patients were identified as candidates for endoscopy. Infants were excluded from study. All patients underwent cystoscopy and retrograde ureteropyelography to start the procedure. In segments less than 2 cm balloon dilation was performed, and for those 2 to 3 cm laser incision was added. Two ureteral stents were placed within the ureter simultaneously and left indwelling for 8 weeks. Imaging was performed 3 months after stent removal and repeated 2 years following intervention. RESULTS: Mean patient age was 7.0 years (range 3 to 12). Of the patients 12 had marked improvement of hydroureteronephrosis on renal and bladder ultrasound. The remaining 5 patients had some improvement on renal and bladder ultrasound, and underwent magnetic resonance urography revealing no evidence of obstruction. All patients were followed for at least 2 years postoperatively and were noted to be symptom-free with stable imaging during the observation period. CONCLUSIONS: Endoscopic management appears to be an alternative to reimplantation for primary obstructive megaureter with a narrowed segment shorter than 3 cm. Double stenting seems to be effective in maintaining patency of the neo-orifice. Followup into adolescence is needed.

Multiple metachronous fibroepithelial polyps in children.

PURPOSE: We present our experience with a new phenotype of fibroepithelial polyps recurring in the urinary tract in children after robotic or laparoscopic pyeloplasty, and discuss the most appropriate treatment for these multiple metachronous neoplasms. MATERIALS AND METHODS: At our institution 14 children had fibroepithelial polyps as the cause of ureteropelvic junction obstruction at pyeloplasty. Of the patients 12 had at least 1 additional polyp in the ureter, necessitating concomitant ureteroscopy at either robotic or laparoscopic pyeloplasty. Of these 12 patients 9 had followup of at least 1 year. RESULTS: In 6 patients with at least 1 year of followup neoplasms were seen on retrograde pyelography and ureteroscopy that were not present on ureteroscopy at pyeloplasty. At 6 months after stent removal following the first recurrence 2 patients (33%) showed a second recurrence on imaging at a different location in the upper tract requiring laser ablation. One of these patients had a third recurrence that required further intervention before all were disease-free. No major intraoperative or preoperative complications developed. CONCLUSIONS: We should always consider the possibility of recurrent fibroepithelial polyps in children with ureteropelvic junction obstruction, and recommend routine retrograde pyelography and ureteroscopy at stent removal after laparoscopic or robotic pyeloplasty. Although ureteroscopic management seems to be the most appropriate modality in children with multiple metachronous fibroepithelial polyps, larger studies are needed.

Robotic pyeloplasty in the pediatric population.

PURPOSE OF REVIEW: Robotic technology is changing the way surgery is performed. It allows in-situ surgery as well as increased magnification and dexterity for minimally invasive surgery. The development and application of pediatric robotic urology are currently manifesting themselves with a rapid growth. RECENT FINDINGS: The procedure most performed with the da Vinci system in pediatric urology is pyeloplasty for ureteropelvic junction obstruction. As with laparoscopic pyeloplasty, robotic-assisted pyeloplasty can be performed by a trans or retroperitoneal approach. Suturing is done with a 6-0 monofilament absorbable suture, but one can utilize any 5-0 or 6-0 suture depending on the size of the patient. Currently, it appears that nothing larger than 6-0 for small children and infants is recommended. Robotic-assisted pyeloplasty in children has been demonstrated to be feasible and to have satisfactory results. SUMMARY: Although there are only a few published series on the long-term outcome to date, the short-term data suggest that outcomes are similar to those of open pyeloplasty in children, and it appears to be more than promising.

Robotic pyeloplasty in the pediatric population.

The procedure most performed with the da Vinci system (Intuitive Surgical, Sunnyvale, CA) in pediatric urology is pyeloplasty for ureteropelvic junction obstruction. As with laparoscopic pyeloplasty, robotic-assisted pyeloplasty (RAP) can be performed by a trans- or retroperitoneal approach. Suturing is done with a 6-0 monofilament absorbable suture, but any 5-0 or 6-0 suture can be used depending on the size of the patient. Currently, it appears that nothing larger than 6-0 is recommended for small children and infants. RAP in children has been demonstrated to be feasible and to have satisfactory results. Although there are only a few published series on the long-term outcome to date, the short-term data suggest that outcomes are similar to those of open pyeloplasty in children, and it appears to be more than promising.

Robotic pediatric urology.

Robotic-assisted minimally invasive surgery is penetrating pediatric urology. The freedom afforded by the "surgical actuators" has led to the expanding adoption of robotics, and it is unlikely that much of laparoscopy will not trend toward some iteration of robotic influence. The da Vinci surgical system (Intuitive Surgical, Sunnyvale, CA) provides delicate telemanipulation, coalesced with three-dimensional visualization and superior magnification. It has bridged the gap between laparoscopy and open surgery. Nonetheless, a confident understanding of pure laparoscopy is paramount in the event that mechanical malfunction is experienced. Robotic pediatric urologic procedures such as pyeloplasty, ureteral reimplantation, abdominal testis surgery, and partial or total nephrectomy with or without ureteral stump removal are routinely performed at select centers offering robotic expertise. Complex reconstructive surgeries such as appendicovesicostomy, antegrade continent enema creation, and augmentation cystoplasty can be performed but are still in their infancy.

Nerve sparing robotic extravesical ureteral reimplantation.

PURPOSE: Laparoscopic transvesical ureteral reimplantation with or without robot assisted surgical devices is being developed as an alternative to open surgery. We sought to review our experience with an extravesical robotic technique, to determine whether postoperative voiding dysfunction might be avoided with pelvic plexus visualization and to evaluate the overall feasibility of this approach to ureteral surgery. MATERIALS AND METHODS: A total of 41 patients underwent robotic extravesical reimplantation for bilateral vesicoureteral reflux. The patients were divided into groups based on bladder capacity as measured by voiding cystourethrogram. The operation was performed via a transperitoneal approach with robotic assistance using the da Vinci Surgical System. RESULTS: Operative success rates were 97.6%. There were no complications. There were no episodes of urinary retention documented by bladder scanning. CONCLUSIONS: Robotic extravesical reimplantation is in its infancy, and visualization of the pelvic plexus appears to be paramount in avoiding postoperative voiding complications. This approach appears to be a feasible and reasonable option for vesicoureteral reflux correction.

Robotic ureterocalicostomy in the pediatric population.

PURPOSE: Ureterocalicostomy is a potential option in patients with ureteropelvic junction obstruction and significant lower pole calicectasis. It is often reserved for patients with a failed pyeloplasty and a minimal pelvis, or patients with an exaggerated intrarenal pelvis. We present our technique of robotic ureterocalicostomy in the pediatric population as a primary modality for an exaggerated intrarenal collecting system not amenable to standard dismembered pyeloplasty, and for secondary ureteropelvic junction obstruction. MATERIALS AND METHODS: Nine patients 3 to 15 years old (mean age 6.5) underwent transperitoneal robotic ureterocalicostomy for ureteropelvic junction obstruction. Six of the patients had recurrent ureteropelvic junction obstruction after primary pyeloplasty performed elsewhere. The remaining 3 patients had an exaggerated intrarenal collecting system with minimal or no appreciable renal pelvis for reconstruction. Outcome measures included operative time, length of hospital stay and postoperative ultrasound at 3 months, as well as resolution of obstruction by diuretic radionuclide imaging at 6 and 12 months of followup. RESULTS: Mean operative time was 168 minutes (range 102 to 204) for the ureterocalicostomy portion. Two patients underwent concomitant pyelolithotomy, with 14 and 21 minutes added to the operative time. Mean hospital stay was 21 hours (range 17 to 26). Diuretic radionuclide imaging, which was performed in all patients at 6 and 12 months postoperatively, revealed no evidence of obstruction in any patient. CONCLUSIONS: Robotic ureterocalicostomy is a viable and technically feasible treatment option for patients with recurrent ureteropelvic junction obstruction, or patients with difficult intrarenal ureteropelvic junctions.

Pediatric flexible ureteroscopic lithotripsy: the children's hospital of Philadelphia experience.

PURPOSE: Therapeutic options currently available for urinary stones include shock wave lithotripsy, percutaneous nephrolithotomy and ureteroscopic treatment. While these treatment options have become the standard of care in the adult population, the same has not necessarily been applied to the pediatric population, despite an increasing prevalence of stone disease in children. We report our flexible ureteroscopic experience with urinary stones in children. MATERIALS AND METHODS: A total of 170 ureteroscopic treatments were performed. Demographic information was collected. Stone burden was measured in millimeters. Operative access, operative times, intraoperative complications, stone-free status and postoperative complications were evaluated. RESULTS: A total of 167 children (89 boys and 78 girls) underwent 170 ureteroscopic procedures for urinary calculi. Mean patient age was 62.4 months at the time of the procedure (range 3 to 218). Mean followup was 19.7 months (range 6 to 39). Mean stone burden was 6.12 mm (range 3 to 24), with an average of 1.3 stones per patient. Retrograde access could not be obtained in 95 of the children (57%). No ureters were actively dilated. Flexible ureteroscopy was performed in all cases regardless of stone location. Stone clearance was 100% for stone burdens 10 mm or less and 97% for burdens greater than 10 mm after 1 ureteroscopy. CONCLUSIONS: Pediatric ureteroscopy is a safe and efficacious modality in the treatment of all upper urinary tract calculi, including lower pole calculi.

Follow-up for laparoscopic renal denervation and nephropexy for autosomal dominant polycystic kidney disease-related pain in pediatrics.

PURPOSE: To present our medium-term experience with laparoscopic renal denervation and nephropexy for autosomal dominant polycystic kidney disease (ADPKD)-related pain in the pediatric patient. MATERIALS AND METHODS: Twelve patients aged 8 to 19 years (mean age 12.4 years) with ADPKD presented with chronic pain refractory to narcotic analgesics. These 12 patients underwent laparoscopic renal denervation of 16 kidneys. RESULTS: Mean operative time was 152 minutes and mean hospital stay was 2.17 days. All patients were pain-free at discharge and remain pain-free at a mean follow-up of 25.5 months. Three adolescent patients each had an episode of flank pain. One was associated with pyelonephritis, another with stones, and the third with trauma and a hematoma. CONCLUSIONS: Laparoscopic renal denervation and nephropexy is a promising option for pediatric patients with uncontrolled ADPKD-related pain.

Robotic pediatric urology.

The number of current advances in robotic surgery for the pediatric population is growing every day: the different procedures range from extirpative to reconstructive, including pyeloplasty, reimplantation, catheterizable channels and augmentation. Despite its early success, robotic surgery still poses many challenges in pediatric patients. Robotics also allows the seasoned laparoscopist to become more proficient and refined, providing a greater armamentarium to expand minimally invasive surgery to more complex reconstructive procedures. The procedure most performed with the da Vinci Surgical System in pediatric urology is pyeloplasty for ureteropelvic junction obstruction. There are many other procedures that can be performed with the robot, such as ureteral reimplantation, and nephrectomy, both total and partial. The reconstructive aspect has been taken to the next level where more difficult procedures, such as appendicovesicostomy and bladder augmentation, can be performed in children.

VR robotic surgery: randomized blinded study of the dV-Trainer robotic simulator.

This research represents a randomized blinded pilot study to evaluate the acceptability and validity of a da Vinci robotic virtual reality simulator platform tested during a pediatric robotic surgery post-graduate course during the annual American Urological Association meeting in June 2007. Course enrollees performed robotic skills tasks on the da Vinci robot and on an offline dV-Trainer and course participant demographic and performance data were analyzed. The majority of learners believed that VR simulation is useful for teaching robotic skills, they believed that the offline trainer can teach robotic skills comparable to a dry lab robotics skills station, and the offline trainer was able to discriminate between experts and novices of robotic surgery, thereby meeting criteria for face, content, and construct validities. This is the first reported acceptability study of a VR robotic surgery simulator as compared to the da Vinci robot system.

Low-dose intrathecal morphine for postoperative analgesia in children.

BACKGROUND: We evaluated the efficacy and safety profile of low-dose (4-5 mcg/kg) intrathecal morphine for postoperative pain management after various surgical procedures in children. METHODS: We reviewed the pain management service database and the medical records of patients who received low-dose intrathecal morphine for postoperative analgesia at The Children's Hospital of Philadelphia between October 2003 and March 2006. Patients had been prospectively followed for 24-48 h after the intrathecal morphine administration. RESULTS: The medical records of 187 patients were examined. The mean age was 5.6 +/- 5.1 yr (median 4.0, interquartile range [IQR] 1.0-10.0). The median maximum pain score during the first 24 h in patients evaluated by the FLACC score and in those evaluated by the numeric verbal rating scale, was 0 (IQR 0-3) and 0 (IQR 0-4), respectively. The mean time to first rescue opioid was 22.4 +/- 16.9 h (range: 0-48 h, 95% CI: 19.9-24.8 h). During the first 24 h after surgery, 70 patients (37%) did not receive any opioids (oral or IV). Of the 117 patients who received opioids, 59 (50%) were managed with oxycodone only. Pain was managed with ketorolac in 33% of patients, either alone (11%) or in combination with IV or oral opioids (22%). The incidence of nausea or vomiting, pruritus, and urinary retention was 32%, 37%, and 6% respectively. One patient had transient postdural puncture headache, while two patients received supplemental oxygen beyond the first 60 postoperative minutes to manage occasional episodes of hypoxemia. No severe respiratory depression requiring assisted ventilation or naloxone administration was observed. CONCLUSION: We conclude that low-dose intrathecal morphine in the pediatric population can be a useful and safe adjunct for postoperative analgesia.

Laparoscopic and robotic complex upper-tract reconstruction in children with a duplex collecting system.

PURPOSE: We suggest that when surgical correction is considered to treat a duplicated collecting system with well-functioning moieties, a laparoscopic approach at the renal level is feasible even in cases requiring complex reconstruction. PATIENTS AND METHODS: Six children between the ages of 4 months and 10 years (mean age 5.2 years) presented with urinary-tract infection, incontinence, or pain and underwent transperitoneal laparoscopic reconstruction for duplex collecting system pathology in renal moieties with preserved function. Five patients underwent laparoscopic upper pole-to-lower pole ureteroureterostomies, whereas one patient underwent a complex reconstruction of a long narrowing defect utilizing a Scardino-Prince vertical flap. Four patients underwent conventional laparoscopy, while the da Vinci Surgical System was used during the surgical procedures of the other two patients. RESULTS: The mean operative time was 3.1 hours (range 2.6-4.9 hours) for the entire procedure, including cystoscopic evaluation. Stents were removed 6 weeks postoperatively. The patients were evaluated with retroperitoneal ultrasonography and either intravenous urography or diuretic radionuclide imaging to assess the anatomic integrity of the reconstruction. The presenting symptomatology resolved in all patients. CONCLUSIONS: We believe that complex laparoscopic upper-tract reconstruction in children who benefit from a parenchyma-preserving approach is possible and should be evaluated against open techniques.