Surgical Technique of Supine Percutaneous Nephrolithotomy in Children / Técnica quirúrgica de la nefrolitotomía percutánea en supino en niños

Percutaneous nephrolithotomy (PCNL) in children has becomemore widely used due to its high efficacy and safety and to the development of miniaturized instruments. A supine approach is promising due to advantages such as better ventilation, reproducibility, and ergonomics. The purpose of the present study is to describe our surgical technique with special considerations in the pediatric population. We used an oblique supine position supported by one silicone gel positioning pad under the hip and another under the ipsilateral flank. The anatomical landmarks used to guide the puncture were the 11th and 12th ribs, the posterior axillary line, and the iliac crest. Initially, a ureteral catheter was introduced endoscopically. A retrograde pyelography was performed to guide the puncture, which was performed using a biplanar technique. A hydrophilic guide wire was then advanced through the needle. Dilation was performed with Alken telescopic dilators until 14 Ch. Fragmentation was performed either with a 13 Ch semirigid cystoscope or a flexible ureteroscope using a holmium: yttrium aluminum garnet (Ho:Yag) laser.We left a double J catheter. Supine PCNL in the pediatric population has comparable efficacy in terms of stone free rate to that of the prone approach as well as less complications. Certain considerations in children are careful padding and placement of the patient close to the edge of the table. Puncture should be guided by ultrasound to reduce radiation exposure. Miniaturized equipment is not widely available, so adaptation of adult equipment for the pediatric population is sometimes necessary.

La nefrolitotomía percutánea en niños se ha vuelto ampliamente utilizada por su alta efectividad, seguridad, y por la miniaturización de los instrumentos endoscópicos. El abordaje en supino es prometedor por sus ventajas, como mejor ventilación, reproducibilidad, y ergonomía. El propósito es describir nuestra técnica quirúrgica con las consideraciones especiales a tener en cuenta en la población pediátrica. Todos nuestros pacientes han sido intervenidos bajo la siguiente técnica quirúrgica: en una posición oblicua en supino, utilizando soportes de silicona ubicados debajo de la cadera y del flanco ipsilateral, se marcan los reparos anatómicos: las costillas once y doce, la línea axilar posterior y la cresta ilíaca. Inicialmente se introduce un cateter ureteral por vía endoscópica, con el cual se realiza una pielografía retrógrada para guiar la punción con una técnica biplanar. Se avanza una guía hidrofílica y, sobre esta, los dilatadores telescopados de Alken hasta un tracto de 14 Ch. Se realiza la fragmentación con un cistoscopio semirígido de 13 Ch o con un ureteroscopio flexible utilizando el láser Ho:Yag. Se deja un cateter JJ. La nefrolitotomía percutánea en la población pediátrica es comparable en términos de tasa libre de cálculos al abordaje en prono, con menos complicaciones. Una consideración importante en niños es una adecuada posición, cerca al eje de la mesa. La punción debe ser guiada por ultrasonido para disminuir la exposición a radiación. La disponibilidad de equipos miniaturizados es limitada, por lo cual usualmente es necesario adaptar los equipos de adultos.

Contemporary management of urinary tract stone disease in children within a high volume institution in Mexico.

OBJETIVO: La urolitiasis en pacientes pediátricos es una condición de baja frecuencia, con tendencia hacia el aumento, por lo que es importante actualizar a urólogos sobre las opciones terapéuticas actuales. Describir las características clínicas, las técnicas quirúrgicas y sus resultados usadas para el tratamiento de la urolitiasis en pacientes pediátricos. MATERIALES Y MÉTODOS: El estudio incluyó todos los pacientes menores de 18 años quienes fueron tratados quirúrgicamente por litiasis urinaria desde el año 2017 al 2020, quienes poseían expedientes clínicos completos y seguimiento en el Hospital General de México. RESULTADOS: Veinte y un pacientes menores de 18 años fueron sometidos a procedimientos quirúrgicos para resolver la litiasis urinaria desde el 2017 al 2020. Los pacientes de sexo masculino fueron más afectados que pacientes del sexo femenino con una relación 3:1. El grupo de edad promedio de presentación fue mayor entre los 1-5 años de edad, la mayoría de pacientes poseían un adecuado índice de masa corporal ajustado por edad. El tracto urinario superior fue el mas afectado, solo 9% se localizó en el tracto urinario inferior, la mayoría de casos se resolvieron con técnicas mínimamente invasivas con una tasa de complicaciones de 14%, llegando al estado libre de litiasis en 90.47% de los casos. CONCLUSIONES: La litiasis urinaria es más común en el sexo masculino, generalmente en el grupo de edad pre-escolar. El índice de masa corporal en la mayoría de los casos se encontraba en rangos adecuados para la edad y el abordaje mínimamente invasivo fue utilizado con mayor frecuencia con 14% de complicaciones y un éxito de 90.47%. BACKGROUND: Pediatric urolithiasis is a rare condition around the world. Its presence and incidence are augmenting in developing countries, remarking the importance for urologists to keep updated to latest trends about its management. OBJECTIVE: The aim of this study was to describe the clinical features and therapeutic surgical options and results for urinary tract stone disease in pediatric patients. MATERIALS AND METHODS: This study included all pediatric patients who undergo surgical procedures to manage pediatric urolithiasis between 2017 and 2020 who had complete medical records and adequate follow-up in the General Hospital of México "Dr. Eduardo Liceaga.". RESULTS: Twenty-one pediatric patients undergo surgical treatment for urinary lithiasis between 2017 and 2020. Males were more affected than female with a relation of 3:1. The mean age at the procedure time was between 1 and 5 years old. The majority of the patients had and adequate body mass index (BMI) according to percentile by age. The upper urinary tract was mostly affected by lithiasis, only 9% of cases were located in the lower urinary tract. The majority of cases were treated with minimal invasive techniques with 14% of complications, and success rate of 90.47%. CONCLUSIONS: Urinary lithiasis is more common in male, usually locates at the upper urinary tract, frequently in the group of 1-5 years old, most cases had an adequate BMI, and the most frequently used techniques are minimal invasive, with a lower rate of complications and great success.

Mini-percutaneous nephrolithotomy versus retrograde intrarenal surgery for the treatment of 10-20 mm lower pole renal stones: a systematic review and meta-analysis.

PURPOSE: To compare the efficacy and safety of mini-percutaneous nephrolithotomy (mini-PCNL) versus retrograde intrarenal surgery (RIRS) for treatment of 10-20 mm lower pole renal stones. METHODS: A comprehensive literature search of PubMed, Scopus, the Cochrane Library, and Web of Science was conducted to identify all studies comparing mini-PCNL and RIRS for 10-20 mm lower pole renal stones before March 2019. Article selection proceeded according to the search strategy based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The meta-analysis was performed with the R program version 3.5.1. RESULTS: A total of five studies were included (two randomized controlled trials and three case-controlled trials) with a total of 587 patients included. The success rate was significantly higher in the mini-PCNL group (OR 1.67; 95% CI p = 0.05). Operative and fluoroscopy times were similar for both groups (MD 2.45; 95% CI p = 0.87 and MD 2.11; 95% CI p = 0.09, respectively). Concerning the hospital stay and overall complication rates, there were no differences between the two procedures (MD 41.94; 95% CI p = 0.18 and OR 1.76; 95% CI p = 0.11). CONCLUSION: Our analysis showed that both procedures are safe for treatment of 10-20 mm lower pole renal stones with similar complication rates, operative times, fluoroscopy times and length of hospital stay, but mini-PCNL was significantly superior in effectiveness with a higher success rate. Based on these results, mini-PCNL may be included in the guidelines as a safe and effective alternative treatment for 10-20 mm lower pole stones.

The role of zinc in urinary stone disease.

In recent years, the role of trace elements in lithogenesis has received steadily increasing attention. It is well documented that some trace elements can influence the morphology and speed of the crystallization process. Zinc has been found in significant amounts in calcium stones relative or organic stones (uric acid and cystine), probably substituting calcium in crystals because of their similarity in charge and size. High Zn levels are present in carbapatite of Randal's plaques suggesting that zinc could promote calcium phosphate deposition in the medullar interstitium. Large-scale epidemiological studies have found an association of increased dietary zinc intake with increased risk of nephrolithiasis in adults but not in adolescents. Most studies examining urinary zinc levels in adults have reported increased urinary Zn excretion in stone formers. In an experimental model of organic crystal formation produced by silencing xanthine dehydrogenase in Drosophila fly, maneuvers that reduce Zn excretion have shown to reduce crystal formation in the lumen of the Malpighian tubules. This is curious because this is not a model of calcium stone formation. Finally, zinc supplementation has been associated with increased admissions for urinary lithiasis in men, but no change in calcium stone formation in children. Perhaps, some of these contradicting findings can be explained in part by the in vitro effect of zinc on the type and amount of calcium phosphate formed: At low concentrations, Zn inhibited the crystal growth of dicalcium phosphate dihydrate, octacalcium phosphate, and apatite, and at higher concentrations, it promoted the formation of amorphous calcium phosphate. Thus, further studies are needed to see whether manipulation of Zn metabolism can inhibit calcium stone formation.

Review on renal recovery after anatrophic nephrolithotomy: Are we really healing our patients?

The main goals for urinary stone treatment are to preserve renal function, reduce or avoid complications related to calculi, and to render the patient free of calculi as soon as possible. Anatrophic nephrolithotomy (ANL) is a valid and useful alternative for conventional staghorn calculi excision. Although excellent stone free rates can be achieved with ANL there are some drawbacks that may be of concern. Morbidity related to intraoperative and postoperative complications is one of them. Another, great concern is the possibility of reduction on renal function related to the procedure itself. This may be related to nephron injury during nephrotomy and parenchymal closure or to ischemic injury. In this review we assess functional results after anatrophic nephrolithotomy.