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 nephrolithotomy for caliceal diverticular calculi: a novel single stage approach

PURPOSE: Current percutaneous treatment of symptomatic caliceal diverticular calculi involves renal access, stone removal, dilation of the diverticular communication, fulguration of the cavity and placement of a nephrostomy tube. We reviewed the outcomes of patients undergoing a novel single stage percutaneous nephrolithotomy technique for radiopaque caliceal diverticular stones that eliminates ureteral catheterization and entry into the renal collecting system. MATERIALS AND METHODS: A total of 21 patients (8 male and 13 female including 1 bilateral) with a mean age of 42.4 years underwent percutaneous nephrolithotomy for caliceal diverticular stones from February 2001 to May 2003. Of the diverticula 12 were upper pole, 4 were interpolar and 6 were lower pole. Infracostal access was established by the urologist directly onto the radiopaque stones without the aid of a ureteral catheter. After balloon tract dilation a 30Fr Amplatz sheath was placed and following stone removal the diverticulum was fulgurated. The infundibulum was neither cannulated nor dilated. A 20Fr red rubber catheter or an 8.5Fr Cope loop was placed into the diverticulum. Stone-free status was assessed by noncontrast computerized tomography on postoperative day 1 (POD1). The drainage tube was removed if there was no urine drainage and the kidney was stone-free. Excretory urography was performed at 3 months to evaluate diverticular resolution. RESULTS: Of 21 patients 20 were discharged home tubeless on POD1 and 18 of 21 (85.7%) renal units were stone- free on POD1 noncontrast computerized tomography. Mean operative time was 58.5 minutes and mean stone burden was 138.9 mm. Mean stone diameter was 11.6 mm and mean diverticular diameter was 15.3 mm. Of 22 renal units 16 had followup excretory urography. All diverticula decreased in size and 14 (87.5%) had complete resolution. CONCLUSIONS: In patients with symptomatic radiopaque caliceal diverticular stones, a single stage procedure without the need for ureteral catheterization combined with direct infracostal diverticular puncture allows for a rapid procedure with little morbidity.     

Ureteropelvic junction obstruction after percutaneous nephrolithotripsy

Percutaneous nephrolithotripsy is reported to have few complications. However, we have treated 6 cases of complete ureteropelvic junction obstruction that occurred at a number of centers after percutaneous nephrolithotripsy. In 2 patients stones were impacted at the ureteropelvic junction, 3 had pre-existing stenosis and 1 had had no previous structural abnormality. All stones were less than 2 cm. in size and 5 were removed by ultrasonic disintegration. A nephrostogram after percutaneous nephrolithotripsy showed complete ureteropelvic junction obstruction in 4 cases and partial obstruction that progressed to total obstruction in 6 days in 1. In 1 case the nephrostogram was normal but occlusion was noted 2 weeks later. Initial management consisted of nephrostomy drainage for an average of 3.2 months. One patient was treated successfully with a ureteral stent for 6 weeks after balloon dilation, 1 had unsuccessful balloon dilation and 1 had undergone an unsuccessful endoscopic pyelolysis. Pyeloplasty was successful in 3 cases. In 1 patient 2 attempts at pyeloplasty failed and nephrectomy was performed. In the remaining patient ureterocalycostomy failed and interposition of a small segment of ileum was done. Pre-existing stenosis of the ureteropelvic junction or a stone impacted at the junction probably contributed to the obstruction and stenosis in 5 patients. The passage of ureteral guide wires should be avoided in these patients and impacted stones should be dislodged before endoscopic removal. Extracorporeal shock wave lithotripsy is an option in these cases if the stone can be dislodged or bypassed with a stent. Patients with pre-existing ureteropelvic junction obstruction might be treated best by open nephrolithotomy and pyeloplasty or by percutaneous nephrolithotripsy and endoscopic pyelolysis for ureteropelvic junction narrowing.     

Percutaneous stone extraction in one single session

Elective percutaneous nephrolithotomy in 137 consecutive cases is reviewed. Radiological puncture, dilation, placement of a nephrostomy tube and endoscopic lithotomy were always done in a single session, with the patient under general anesthesia. Thirty-six patients had a renal operation at the site of percutaneous nephrolithotomy. An adequate tract was formed in 94.9% of the cases. Ninety percent of the targeted calculi were removed successfully. Average anesthesia time was 90 min and mean hospitalization 6 days. Complications were few and patients returned to work earlier than after an open operation.     

Immediate closure of nephrostomy tube wounds using a tissue adhesive: a novel approach following percutaneous endourological procedures

PURPOSE: We assessed the feasibility of immediate sealing of nephrostomy tube wounds after percutaneous surgery using a tissue adhesive. MATERIALS AND METHODS: The study represents a prospective series of 27 consecutive percutaneous procedures. After nephrostographic exclusion of infrarenal urinary obstruction the nephrostomy tubes were removed and the wound edges were glued together using 2-octyl cyanoacrylate. The wound was covered by gauze to assess the efficiency of sealing and the patients were followed clinically. Another consecutive series of 20 patients who had been treated during 6 months before the current study were used for comparison. The nephrostomy wound in this group was dressed and left to close spontaneously. RESULTS: A total of 27 percutaneous procedures were performed in 25 patients with a median age of 51 years (range 9 to 77). There were 26 cases of percutaneous nephrolithotomy for an average stone burden of 32.6 mm. (range 16 to 70) and 1 pediatric case of percutaneous antegrade balloon dilation of ureteral stricture related to Cohen reimplantation. Median size of the nephrostomy tubes was 16Fr (range 12Fr to 24Fr) and they were maintained a median of 4 days (range 1 to 16) postoperatively. Urinary leakage ceased immediately after tissue adhesive application in all cases. One patient in whom renal colic developed secondary to edema of the ureteral orifice underwent temporary stenting in retrograde fashion. There were no additional complications at a median followup of 5 months (range 3 to 7). The study group had a significantly shorter hospital stay than the wound dressing group (p <0.001). CONCLUSIONS: Wound sealing following nephrostomy tube removal using 2-octyl cyanoacrylate appears to be a safe, simple and efficient method for immediate abolishment of urinary leakage. This novel approach avoids patient and medical personnel inconvenience, permitting early release from the hospital without physical and social limitations related to persistent wound urinary discharge.     

Nefrolitectomía percutánea tubeless con posibilidad de reexploración: la combinación perfecta

ObjectivesTo evaluate an alternative approach to tubeless surgery that allows a second percutaneous procedure using the same nephrostomy tract.MethodsTwenty patients underwent percutaneous nephrolithotomy from September 2012 to May 2013 at our institution. Inclusion criteria were: absence of urinary infection, single puncture and operative time less than 2 h. Following the procedure the initially placed ureteral catheter was exteriorized through the working sheath by tying a non-absorbable suture to its end. On postoperative day 1 all patients were studied with non-enhanced CT or X-ray film. If the patient was rendered stone free, the stent was removed along with the urethro-vesical catheter. If a residual stone was present, we recovered the ureteral catheter and used the same nephrostomy tract for a second endoscopic procedure. Patients were assessed for pain, postoperative complications, length of stay, stone free rate, hematocrit and creatinine variations.ResultsThirteen patients met the inclusion criteria. No major complications related to the stent placement and its exteriorization were seen. Two patients required a second percutaneous procedure successfully achieved recovering the ureteral catheter through the nephrostomy tract.ConclusionWe present a safe and simple modification of tubeless percutaneous nephrolithotomy, with its well-known clinical benefits but maintaining a safe path for an eventual second look procedure if necessary.     

Combined percutaneous and retrograde approach to staghorn calculi with application of the ureteral access sheath to facilitate percutaneous nephrolithotomy

PURPOSE: We describe our technique and clinical experience with application of the ureteral access sheath for single access ablation of staghorn and partial staghorn calculi. MATERIALS AND METHODS: We retrospectively reviewed our experience with 9 patients who underwent percutaneous nephrolithotomy for staghorn (6) or partial staghorn (3) renal calculi using a combined antegrade and retrograde approach. Patient data, operative parameters, efficacy of stone ablation and convalescence parameters were reviewed. RESULTS: Mean operative time for the primary procedure was 3.1 hours with a mean estimated blood loss of 290 ml. Postoperatively, the mean analgesic requirement was 33.2 mg. MSO(4) equivalents. Hospital stay was 3.2 days. There were no major and 4 minor (44%) complications. No patient required transfusion. Complete stone clearance was achieved in 7 of the 9 cases (78%) using a single percutaneous nephrostomy tract. CONCLUSIONS: Our preliminary clinical experience using the ureteral access sheath during percutaneous nephrolithotomy for simultaneous antegrade and retrograde stone treatment has been favorable. A large renal stone burden can be successfully managed with a single percutaneous access and limited blood loss.     

Percutaneous nephrolithotomy in children: lessons learned in 5 years at a single institution

PURPOSE: We retrospectively compared morbidity and success rates in children who underwent percutaneous nephrolithotomy with 3 different sizes of instruments. MATERIALS AND METHODS: Percutaneous nephrolithotomy was performed using adult instruments via a 26Fr tract in 23 patients, using pediatric instruments via a 20Fr tract in 13 and using minimal access (14Fr) in 10. Percutaneous nephrolithotomy was performed using general anesthesia with parenteral antibiotic prophylaxis. Cystoscopy and retrograde pyelography were performed, and 5Fr to 6Fr soft ureteral catheters were placed during each procedure initially. Percutaneous access was established via fluoroscopic guidance with the patient in the prone position. Pneumatic, ultrasonic and holmium laser lithotriptors were used for in situ lithotripsy. A 14Fr nephrostomy catheter was placed at the end of the procedure in the 26Fr and 20Fr groups, and in the minimal access group the ureteral stent was left indwelling in cases of atraumatic procedure with no residual fragments. RESULTS: Mean patient age was 13.2, 5.9 and 6.3 years, respectively, in the 26Fr, 20Fr and minimal access groups (p=0.000). Sex distribution, previous surgery, stone size, surgery and fluoroscopy times, mean hemoglobin decrease and hospitalization time did not differ between the groups. However, blood transfusion rate was higher in groups 1 and 2. Stone-free rates were 69.5%, 80% and 90%, respectively, in groups 1 to 3. Overall, adjuvant shock wave lithotripsy treatment was needed in 3 children. CONCLUSIONS: Smaller instrument size to 20Fr did not significantly increase the operative time, and resulted in the same success rates as the adult sized devices. However, low blood transfusion rates were only reached in the minimal access percutaneous nephrolithotomy group.     

微创经皮肾取石术治疗独立肾结石

目的：探讨微创经皮肾取石术治疗孤立肾结石的临床疗效与手术技巧。方法：利用微创经皮肾取石术治疗孤立肾结石18例，14例患者行一期微创经皮肾取石．4例行经皮肾穿刺造瘘术，5～7天后行二期取石术。结果：结石清除15例（83．3％）。在结石残留的3例患者中，1例残留结石下移至输尿管下段，用输尿管镜将结行取出；余2例结石残留。肾内，未作进一步处理，本组患者术后肾功能基本恢复正常或好转。结论：微创经皮肾取石术治疗独立肾结石是一种安全、有效的方法。     

B超引导下经皮肾镜钬激光碎石取石术治疗肾盏憩室结石10例报告

目的：探讨经皮肾镜钬激光碎石取石术（PCNL）治疗肾盏憩室结石的安全性及疗效.方法：对接受PCNL治疗的10例肾盏憩室结石患者的临床资料进行回顾性分析总结.结果：9例患者均行单通道一期碎石及取石,平均手术时间90 min,平均留置肾造瘘管7天,平均住院12天,术后住院时间7天.1例患者穿刺失败中转开放手术,均未出现大出血或邻近器官损伤等并发症,术后复查尿路平片示结石全部取净.结论：PCNL术治疗肾盏憩室结石安全、可行,疗效确切,与开放手术相比,能减少术中、术后出血及并发症,结石取净率高.具有创伤小、恢复快等优点.     

腹腔镜联合经皮肾穿刺取石术治疗肾囊肿并肾多发性结石

目的 介绍腹腔镜联合经皮肾穿刺取石术治疗肾囊肿并肾多发性结石的技术要点和初步经验。 方法 选取20例肾囊肿并肾多发性结石患者行腹腔镜联合经皮肾穿刺取石术治疗肾囊肿并肾多发结石。结石最大4x3cm,最小1x0.5cm。先用腹腔镜行肾囊肿去顶术。然后根据术前CTA+CTU片制定手术方案和穿刺部位。在腹腔镜监视下行经皮肾穿刺,建立F18取石通道取石。 结果 20例患者均获得成功。结石全部取尽,手术效果满意。手术平均时间90min。没有出现出血、尿漏、肾盏颈撕裂和输尿管狭窄等严重并发症。术后平均住院时间5d。 结论 腹腔镜联合经皮肾穿刺取石术可以同时处理肾脏多种疾病。在处理肾盏内结石或肾盏颈细长,肾内型肾盂的患者较腹腔镜肾盂切开取石术容易操作,盏颈损伤小和结石清除率高。是腹腔镜肾盂切开取石术有益的补充和支持。     

微造瘘经皮肾输尿管镜取石术治疗复杂性输尿管上段结石205例报告

目的：探讨微造瘘经皮肾输尿管镜取石术（MPCNL）治疗复杂性输尿管上段结石安全性和疗效。方法：对205例复杂性输尿管上段结石患者采用MPCNL进行治疗,其中男108例,女97例,平均年龄（39．8±8．9）岁,左侧114例,右侧91例。合并轻度积水61例,中度积水94例,重度积水50例。结果：205例Ⅰ期结石清除率100％,平均手术时间（76土23）min,肾造痿管留置时间平均（5．1±1．8）天,平均住院时间（9．2±1．9）天;1例出现肾周脓肿,经CT定位下行穿刺引流治愈,随访200例1～6个月,KUB、IVU均未查见残石和输尿管狭窄,患者肾功能有不同程度恢复。结论：MPCNL治疗复杂性输尿管上段结石完全有效。     

Practical experiences with antegrade local chemolysis of struvite/apatite, uric acid and cystine calculi in the kidney

In 18 patients (20 kidneys) with struvite/apatite-, uric acid- and cystine stones antegrade local chemolysis was performed via percutaneous or operative nephrostomy. Complete stone dissolution was achieved in 11 kidneys, while in six kidneys partial dissolution of stones was performed. In these six cases added instrumental manipulations shortened the time of therapy. In three cases chemolysis was unsuccessful. Average irrigation time was 21 days per renal unit. Only minor complications like dysuria and skin rashes were seen. Due to long time of irrigation we recommend chemolitholysis mainly as an additional form of therapy in case of residual stones after operative or percutaneous nephrolithotomy.     

Percutaneous nephrolithotomy in patients with previous renal surgery

Although safe and effective, nephrolithotomy sometimes is difficult. 224 patients have undergone percutaneous stone extraction surgery. Two groups were established according to previous open renal surgery. 79 patients had had previous surgery and 145 patients were initially treated by percutaneous nephrolithotomy. Bleeding and operative time, i.e. puncture of the kidney, dilation of the tract and lithotripsy were greater in the group with previous renal surgery. However, no statistical difference was verified. In conclusion, percutaneous lithotripsy is a safe and effective method with minimal morbidity even in patients with previous renal surgery.     

Percutaneous nephrolithotomy in the spinal cord injury population

We evaluated 23 male spinal cord injury patients who underwent percutaneous nephrolithotomy for the success rate of stone removal and the incidence of operative complications. There were 18 quadriplegic and 5 paraplegic patients, and 5 had bilateral procedures. Of the kidneys 7 had staghorn calculi, 8 had pelvic and caliceal combinations, 6 had large multiple caliceal stones, 4 had large (more than 2.5 cm.) pelvic stones and 3 had pelvic stones less than 2.5 cm. Placement of a nephrostomy tube and stone extraction were performed as a single procedure with the use of general anesthesia in all but 4 patients. Our results showed that 19 of 21 compliant patients (90.4 per cent) were free of stone, with an average of 2.04 procedures per patient. A total of 47 procedures was performed, with an average operative time of 1 hour 45 minutes. Major complications were associated with 4 of the 47 procedures (8.5 per cent), and consisted of a respiratory arrest, 2 perirenal abscesses and a hydrothorax. Minor complications included fever (more than 101.5F) in 64.3 per cent and retained stones in 14.3 per cent of the kidneys operated upon, dislodged nephrostomy tubes in 12.6 per cent of the procedures (21.4 per cent of the kidneys operated upon), and anemia requiring transfusion in 17.0 per cent (8 of 47) of the procedures (27.8 per cent of the kidneys operated upon). The presence of infected stones, prior operative procedures and medical complexity of these patients make complications more frequent. Nevertheless, percutaneous nephrolithotomy is a safe and effective procedure for the spinal cord injury population.     

二期微创经皮肾镜取石术治疗上尿路结石并感染

目的 探讨二期微创经皮肾镜取石术（MPCNL）治疗上尿路结石并感染的方法与临床效果。 方法 回顾性分析208例采用MPCNL治疗的上尿路结石并感染患者的临床资料。208例患者均一期行经皮肾穿刺造瘘,二期行经皮肾镜取石术。单通道取石179例,双通道取石29例。1次取石150例,2次取石52例,3次取石6例。 结果 本组结石清除率98.1％（204/208）,平均取石时间110min,术中平均出血30ml,均未输血。平均住院14天。9例术后出现高热（>39℃）,其余未见严重并发症。 结论 二期MPCNL对于治疗合并感染的上尿路结石安全有效,尤其对结石合并脓肾、梗阻性肾功能衰竭等全身状况较差的患者,二期手术可作为首选。     

输尿管软镜与经皮肾镜治疗一期经皮肾镜术后多发性残石的比较

目的比较输尿管软镜（RIRS）和经皮肾镜碎石取石术（PCNL）处理一期PCNL术后多发性残石的临床疗效。 方法回顾性分析2016年8月至2018年8月中山大学附属东华医院采用PCNL术后多发性残石78例患者的资料,其中男42例,女36例,平均年龄（46±13）岁,残石2～5个,单个结石直径≤2 cm。78例患者的操作均在一期手术后5～7 d肾造瘘管引流液变清后进行,根据残石的处理方案分为输尿管软镜组（R组）43例和经皮肾镜组（P组）35例,R组进行逆行输尿管软镜取石,P组在原经皮肾镜通道的基础上进行多通道PCNL。 结果所有操作均成功进行,无严重并发症发生,P组和R组的手术时间、结石清除率等差异无统计学意义;P组在平均血红蛋白浓度下降值（0.95±0.86 vs 0.29±0.45 g/dl）、住院时间（5.7±1.9 vs 1.8±1.5 d）和术后第1天疼痛视觉模拟评分（VAS） （5.1±1.1 vs 1.6±0.7）上显著高于R组（P<0.01）;P组和R组术后第1天血肌酐较术前升高值分别为（0.22±0.04）mg/dl和（0.07±0.01）mg/dl,（P<0.05）。 结论RIRS和PCNL处理PCNL术后多发性残石均是安全有效的,输尿管软镜对患者的的影响和术后恢复等方面具有一定的优势。     

Modified anatrophic nephrolithotomy for complete staghorn calculus disease -- does it still have a place?

OBJECTIVE: To report our experience with open surgery for the management of complete staghorn calculi using a modified anatrophic nephrolithotomy technique. MATERIAL AND METHODS: Between 1990 and 2001, 24 patients underwent anatrophic nephrolithotomy in our department. Bilateral complex stone disease was present in 9 patients, so that a total of 33 procedures were carried out. Preoperative evaluation included excretory urography (intravenous pyelography) and routine laboratory study in all patients and in 9 patients renal function was assessed using (99m)Tc dimercaptosuccinic acid renal scans before and 6 months after surgery. Postoperative follow-up consisted of kidney-ureter-bladder (KUB), ultrasound (U/S), urinalysis and urine culture. RESULTS: The mean operative time was 180 min, mean blood loss was 500 ml and renal ischemia time ranged between 10 and 35 min. Deep vein thrombosis occurred on the 5th postoperative day in an obese female patient. No other operative or postoperative complications were observed. Mean hospital stay was 8.2 days (range 7-12 days). The stone-free rate was 83.3%. Long-term follow up demonstrated stone fragments <4 mm in diameter in 4 patients (16.6%). Renal function remained unchanged or slightly improved in 15 patients; a slight worsening of renal function was noted in 9 patients (from an average of 39% before to 35% after the procedure). CONCLUSIONS: Anatrophic nephrolithotomy, although a major operative procedure, remains the most appropriate method for the one-stage management of a selected group of patients harboring large staghorn calculi with infundibular stenosis, and is associated with the highest stone-free rates.     

标准通道经皮肾镜取石术结合负压吸引治疗合并脓肾的多发性肾结石11例报告

目的：评估标准通道经皮。肾镜取石术结合负压吸引治疗合并脓肾的多发性肾结石的安全性及有效性。方法：回顾性分析2009年10月～2012年2月期间收治的11例合并脓肾的多发性肾结石患者临床资料：主要结石大小（2．0cm×2．5cm）～（7．0cm×3．5cm）。2例术前中段尿培养阳性;术中穿刺后均明确诊断合并脓肾。11例均采用标准通道经皮肾镜取石术进行治疗,同时连接负压吸引,患侧上尿路置入Fs输尿管导管持续引流脓液。其中I期行肾造瘘3例,碎石8例,Ⅱ期手术9例,Ⅲ期手术2例。结果：I期手术时间15～70min,平均47rain。出血50~200ml,平均约100ml,未输血,无泌尿道严重损伤、周围脏器损伤等并发症。术后未出现严重出血、肾周脓肿、感染性休克。术后发热4例,选择敏感抗生素或广谱抗生素加强抗感染及支持治疗后症状消失。2例残余少许结石,行ESWL治疗。结石清除率为81．8％（9／11）。结论：采用标准通道超声碎石结合负压吸引并分期手术治疗合并脓肾的多发性肾结石,可充分引流脓液,控制感染,快速清除结石,同时避免了严重并发症,临床安全、有效。     

One-stage tract dilation for percutaneous nephrolithotomy: is it justified?

PURPOSE: To assess the feasibility of one-stage acute dilation of the nephrostomy tract with a 30F Amplatz dilator in patients who are candidate for percutaneous nephrolithotomy (PCNL) regardless of whether there is a previous renal scar to make the procedure less time consuming and more cost effective. PATIENTS AND METHODS: The outcomes of one-stage tract dilation for PCNL in 100 consecutive patients with and without a history of ipsilateral open stone surgery (OSS), treated by one surgeon, were examined prospectively. Forty-six patients (group 1) had a history of ipsilateral OSS, and 54 patients (group 2) did not have this history. Demographic data as well as intraoperative information, such as access time and radiation exposure time during access, were recorded. The success of the access technique and its bleeding complications were analyzed between the two groups. RESULTS: By applying a "one-stage" technique, the targeted calix could be entered with a success rate of 93%. There was no difference in the procedural success rate between groups 1 and 2 (93.5% v 92.6%, respectively). All seven failed attempts (7%; three with previous OSS) were managed successfully using an Alken dilator to gain access to the proposed calix in the same session. Previous OSS did not impact access time, radiation exposure time during access, postoperative hemoglobin drop, and bleeding complications. There were no visceral and vascular injuries. CONCLUSIONS: One-stage tract dilation for PCNL is a safe and effective method in almost every adult patient.