Elias Wehbi

Inappropriate Use of Ultrasound in Management of Pediatric Cryptorchidism

BACKGROUND AND OBJECTIVES: There is a limited role for ultrasound in the management of an undescended testicle (UDT). We hypothesized that ultrasound remains overused by referring physicians. Our goal was to characterize the trends, patterns, and impact of ultrasound use for UDT and to reaffirm its limited diagnostic value for this indication. METHODS: The records of boys aged 0 to 18 years with UDT in Ontario, Canada, between 2000 and 2011 were reviewed by using health administrative data housed at the Institute for Clinical and Evaluative Sciences (ICES). A second review of boys referred to our institution with UDT between 2007 and 2011 was conducted to complement the health administrative data. Trends in frequency, distribution, and costs of ultrasound use were assessed. Time delays between diagnosis and definitive management were compared between the ultrasound and non-ultrasound groups. Using our institutional data, we analyzed demographic patterns of ultrasound use and compared its diagnostic accuracy by using surgical findings as the gold standard. RESULTS: Ultrasound was used in 33.5% of provincial referrals and 50% of institutional referrals. Children who underwent ultrasound experienced an approximate 3-month delay in definitive surgical management. Ultrasound correctly predicted physical examination findings in only 54% of patients. Physicians in community practice, and those with fewer years in practice, were more likely to order ultrasound. CONCLUSIONS: Ultrasound has limited value for the management of UDT but remains widely overused, with an increasing trend over time. This practice has negative implications for access to care and cost-containment. Widespread educational efforts should be undertaken, targeting current and future referring physicians.

Measurement of Differential Renal Function by Scintigraphy in Hydronephrotic Kidneys: Importance of Conjugate Views for Accurate Evaluation

PURPOSE Traditionally a single posterior view is used to measure differential renal function during nuclear renal scintigraphy. Nevertheless, experimental data show important variation in this measurement in the setting of significant hydronephrosis. To date, the impact of degree of hydronephrosis on the accuracy of differential renal function determination has not been addressed. We evaluated the discrepancy between function measured by anterior and posterior views, and the relationship to varying degrees of hydronephrosis. MATERIALS AND METHODS We retrospectively reviewed consecutive mercaptoacetyltriglycine renal scans from 2009 to 2011. Ultrasounds were reviewed and degree of hydronephrosis was recorded using anteroposterior pelvic diameter. Absolute percent difference in differential renal function between each view (anterior minus posterior) was calculated and correlated to anteroposterior pelvic diameter. Patients were stratified into 4 groups according to anteroposterior pelvic diameter, ie less than 10 mm, greater than 10 mm, greater than 15 mm and greater than 25 mm. RESULTS A total of 519 scans with corresponding ultrasounds were analyzed. Median patient age was 2.26 years. Kidneys with a larger anteroposterior pelvic diameter had a greater discrepancy in function on anterior and posterior views. There was a meaningful discrepancy for anteroposterior pelvic diameter greater than 10 mm (p = 0.034) and greater than 25 mm (p = 0.032). Several statistical models were used to identify a meaningful cut point of 15 mm, where the discrepancy in anterior and posterior views became significant (p = 0.001). CONCLUSIONS The use of single views during nuclear renography for grossly hydronephrotic kidneys is often inaccurate. The discrepancy in differential renal function obtained on the anterior and posterior views is adversely impacted especially as anteroposterior pelvic diameter increases beyond 15 mm. Therefore, we suggest incorporation of conjugate views for estimating differential renal function in patients with hydronephrosis.

A Reanalysis of the RIVUR Trial Using a Risk Classification System

Purpose: The RIVUR (Randomized Intervention for Children with Vesicoureteral Reflux) trial showed a 50% decrease in the risk of urinary tract infection recurrence in children with reflux receiving continuous antibiotic prophylaxis. We reanalyzed the RIVUR data with the purpose of using a risk classification system to identify children who are more likely to benefit from continuous antibiotic prophylaxis. Materials and Methods: Data from 607 children enrolled in the RIVUR trial were obtained from the National Institute of Diabetes and Digestive and Kidney Diseases Central Repository and analyzed. We stratified these children into low and high risk categories. The proportion of children and risk of urinary tract infection recurrence in the stratified treatment groups were compared. Results: Of the children 385 (63.9%) were stratified into the low risk and 217 (36.1%) into the high risk category. The proportions of children with urinary tract infection recurrence were not significantly different in the low risk category between the placebo and continuous antibiotic prophylaxis groups (p = 0.151), while urinary tract infection recurrence was significantly higher in the placebo group (31.5% vs 11.4%, p = 0.001) for high risk children. Furthermore, high risk children on placebo had a 3.7‐fold increased risk of urinary tract infection recurrence during 2 years of followup compared to those on continuous antibiotic prophylaxis. Conclusions: Although the RIVUR trial concluded that children with vesicoureteral reflux benefit from continuous antibiotic prophylaxis, our reanalysis of the data demonstrates that high risk children benefit more, with a number needed to treat of 5 compared to 18 in low risk children. The clinical implications of these findings suggest a need to refine current indications for continuous antibiotic prophylaxis in children with reflux, supporting a shift toward a “selective” risk based approach for management.

Kelly procedure for exstrophy or epispadias patients: Anatomical description of the pudendal neurovasculature.

INTRODUCTION Adequate penile length in males with bladder exstrophy or epispadias is a major challenge. Kelly previously described a surgical technique of a single stage reconstruction for patients with exstrophy or epispadias that potentially achieves significant penile lengthening by completely detaching the insertion of the corpora cavernosa from the ischiopubic rami. However, because of the possibility of damage to the pudendal neurovascular supply that may lead to partial or complete penile loss, this technique has not gained popularity. The aim of this study is to describe the surgical anatomic relationship of the pudendal neurovascular bundle (NVB) to the ischiopubic rami and to determine a safer approach to dissection during the Kelly procedure. METHODS We performed meticulous dissection in three formalin-fixed and one fresh adult male cadavers to demonstrate the anatomical relationships between the pudendal neurovascular supply of the penis and the cavernosal insertion to the ischiopubic ramus. RESULTS AND DISCUSSION We demonstrated the relationships and distance between the NVB and the area of separation between the crus and the ischiopubic ramus at the level of the periosteum. The insertion of the crus to the ischiopubic ramus is inferior lateral, whereas the NVB lies at a superior medial position. This anatomical relationship is best visualized when the dissection is carried out starting from the distal portion of the NVB and proceeding proximally. This area of the periosteum is avascular and the NVB can be preserved safely as long as the dissection is conducted at that subperiosteal level. Based on this cadaver dissection study, we suppose that detaching the corporal cavernosa from the pubic bones at the subperiosteal level allows for a safe distance to be maintained from the pudendal nerve at all times. We believe that if a surgeon performs the dissection inferiorly and laterally, the corpora cavernosa can be safely detached from the ischiopubic ramus and injury to the pudendal vessels and nerve can be avoided. However, it must be noted that there are limitations to applying the results from this study of normal, adult cadavers to the anatomy of children and adolescents with exstrophy or epispadias, who form the largest proportion of patients who are candidates for this procedure. CONCLUSION This anatomical study demonstrates the relationship between the pudendal NVB, the crus, and the ischiopubic ramus. We demonstrated how the separation of the crus from the ischiopubic periosteum might be performed more safely.

Urinary Tract Infections and Vesicoureteral Reflux

• The presentation of urinary tract infections (UTIs) in neonates differs from that seen in older children.

Home Urodynamic Pressures and Volume Measurement for the Neurogenic Bladder: Initial Validation Study

Purpose: We evaluated the ability of a bladder pressure/volume diary to identify patients at risk for increased intravesical pressures. Materials and Methods: Patients dependent on clean intermittent catheterization used ruler based manometry to measure intravesical pressures before leakage or scheduled drainage at home. We prospectively collected clinical, urodynamic and bladder pressure/volume diary data in patients with spina bifida who were optimized on anticholinergic therapy and clean intermittent catheterization. Measurements were taken with patients in the supine position with relaxed abdominal muscles. We defined increased pressure as detrusor pressure greater than 30 cm water as measured by urodynamics. ROCs were plotted to correlate bladder pressure/volume diary variables with abnormal intravesical pressures, and the most sensitive variable in determining abnormal intravesical pressures was sought as the end point. Results: A total of 30 patients with a mean age of 10 years (range 1 to 20) were included. Home pressures measured at maximal clean intermittent catheterization volume and mean bladder pressure/volume diary pressures were most reliable in predicting urodynamic pressures greater than 30 cm water (AUC 0.93 and 0.87, respectively). Home pressures measured at maximal clean intermittent catheterization volumes less than 20 cm water were associated with normal bladder pressures (less than 30 cm water) on urodynamics, with a sensitivity of 100% and a specificity of 80%. Conclusions: Home manometry less than 20 cm water provides a reliable measurement of safe pressures. A bladder pressure/volume diary is feasible and can aid in monitoring pressures at home without the additional cost and morbidity of urodynamics. A bladder pressure/volume diary may be a useful tool to help identify patients who would benefit from urodynamic testing.

Endoscopic correction of vesicoureteral reflux simulator curriculum as an effective teaching tool: Pilot study.

INTRODUCTION It has been well recognized that simulators are effective tools to teach and evaluate technical skills in laparoscopic surgery. Endoscopic injection for the correction of vesicourteral reflux has a definite learning curve. Surgeon experience has also been demonstrated to have an important role in the outcome of the procedure. Simulated training allows for practice in a realistic setting without the inherent risk of harm to the patient. This stress free environment allows the trainee to focus on the acquisition of surgical skills without worry about surgical outcome. OBJECTIVE The aim was to validate a porcine bladder simulator curriculum for training and assessment of the surgical skills for the endoscopic correction of vesicoureteral reflux. STUDY DESIGN We developed a porcine bladder-based dextranomer/hyaluronic acid (Dx/HA) injection simulator consisting of a dissected ex vivo porcine bladder in a polystyrene box with the distal ureters and urethra secured (Figure). We performed content validation by five experienced pediatric urologists. We then organized a simulator curriculum, which included lecture, demonstration, and a 2-h hands-on training on the simulator. Content, discriminant, and concurrent validation of the simulator curriculum were carried out using 11 urology trainees at different levels of expertise. All the trainees were evaluated for each step of the procedure of both their first and last performances on the simulator. RESULTS Overall, the model demonstrated good content validity by all experts (mean questionnaire score 92%). The simulator curriculum demonstrated a significant improvement in the performance of the trainees between their first and last evaluations (56-92%; p = 0.008). Specific parts of the procedure that showed significant improvement (p < 0.05) were identification of the ureteral orifice, ureteral orifice hydrodistention, first and second injection, and location, size, and depth of the mound after injection. DISCUSSION The Dx/HA endoscopic injection simulator is an effective training tool to improve the performance of the surgeon carrying out the procedure. This teaching tool may be used to help improve the performance of the surgeon carrying out the procedure. This teaching curriculum may shorten the early learning curve historically associated with the procedure and provide a greater understanding of the technical components of successful endoscopic vesicoureteral reflux correction. Additionally, the implementation of this simulator within the developed curriculum can improve the performance of training urologists in all steps of the challenging technique of Dx/HA needle injection confirming concurrent validity. The next step in evaluation of this surgical skill-training curriculum would be to determine if the improvement in skill performance observed during training translates to improved performance in the clinical realm, or predictive validity. LIMITATIONS Some small differences exist between the porcine model and human ureteral orifices. In the porcine model the ureteral orifices are located medially and distally in the bladder neck, which make injection more challenging. Participants suggested that after practicing with the simulator endoscopic injection to a human ureteral orifice would be easier. CONCLUSION The simulator curriculum was able to improve the performance of the surgeon carrying out the procedure during subsequent simulations.