Abstract
Purpose:
To present the safety and efficacy of totally ultrasonography-guided percutaneous nephrolithotomy (PCNL) for managing urinary stones in pediatric patients.
Patients and Methods:
Ten children with a mean age of 5.4 (3–11) years underwent totally ultrasonography-guided PCNL from March 2013 to November 2013. The pyelocaliceal system was punctured with the patient in the prone position by using ultrasonographic guidance, and the tract was dilated using a single-shot dilation technique. All steps of renal access were performed by using ultrasonography; no fluoroscopy was used. PCNL in all cases was performed by using adult instruments.
Results:
The mean stone size was 28.9±6.7 mm (range 17–35 mm). The mean access time to stone was 4.45±2.25 minutes (range 3–10 min). The mean nephroscopic time was 45.9±17 minutes (range 20–80 min). The stone-free rate was 83%. Mean hospital stay of patients was 3 days (range 2–5 days). No major complications were happened. Only one patient needed ureteral stent insertion because of urinary leakage from the nephrostomy tract.
Conclusion:
Our experience with totally ultrasonography-guided PCNL using adult size instruments in children revealed proper results and acceptable complications compared with the standard technique of PCNL. Likewise, this alternative method has the advantage of preventing radiation hazard.
Introduction
Percutaneous removal of renal calculi has become an established and successful procedure in adults. 1 Of children with renal calculi, 20% to 44% have metabolic disturbances and anatomical abnormalities. A retrospective study revealed a high recurrence rate of stone formation necessitating surgical interventions in this group of patients. 2 Some previous studies have confirmed the efficacy and safety of percutaneous nephrolithotomy (PCNL) in pediatric patients. 3,4
Sometimes PCNL in children is performed by using fluoroscopic guidance, but radiography may have some adverse effects in children. A few studies revealed the efficacy of the combination of ultrasonography and fluoroscopy in PCNL in children. 5 Although previous reports have confirmed the safety and efficacy of PCNL using adult size instruments in pediatric patients, 3,6 there is no general agreement regarding the use of this size instrument during PCNL.
In this study, we present preliminary results of totally ultrasonography-guided PCNL using adult size instruments in pediatric patients with large renal calculi.
Patients and Methods
Medical records of 10 patients (2 patients with bilateral staghorn stone needed two sessions of PCNL for complete stone removal) with a mean age of 5.4 (range 3–11) years who had undergone totally ultrasonography-guided PCNL between March 2013 and November 2013 were reviewed. Some variables such as stone size and location, anatomic abnormality, access time, nephroscopic time, changes in hemoglobin, hospital stay, success rate, and complication rate were assessed. Urine culture was obtained from all cases, and if the culture was positive, the patient received antibiotics for 2 weeks. Ultrasonography and intravenous urography were performed for all the patients before operation (CT-scan was not recommended because of the high dose radiation). The patients were followed by radiography of the kidneys, ureters and bladder and ultrasonography 2 weeks after operation. The stone-free rate was defined as residual fragments smaller than 4 mm.
Surgical technique
In this study, the procedures were performed by one endourologic surgical team, and no interventional radiologist was involved.
After general anesthesia with the patient in the dorsal lithotomy or frog leg position, a 4F ureteral stent was inserted by a 14F cystoscope for all patients, and a 10F to 12F Foley catheter was fixed. Then, with the patient in the prone position, the pyelocaliceal system was punctured by using an 18-gauge Chiba needle that was attached to the side of a 3.5 MHz ultrasound probe. The stone location and degree of hydronephrosis in each calix were the main factors for selection of the targeted calix. When there was no significant hydronephrosis, the pyelocaliceal system was expanded using saline injection.
Afterward, the tract was dilated using a single-shot dilation technique. 7,8 In the one tract dilation technique by attachment of the needle to the ultrasound curved probe, an 18-gauge access needle was passed into the appropriate calix. Its stylet was removed, and a 0.035-inch J-tipped guidewire was introduced into the targeted calix. The skin over the puncture site was incised, and the nephrostomy tract was first dilated by an 8F polyurethane dilator. After the dilator was removed, the Alken guide was replaced, and then a single 26F Amplatz dilator was passed on the Alken guide, on which an Amplatz sheath was introduced into the renal collecting system. We ensured the correct position according to the shadow of the Amplatz sheath during tract dilation; then the complex of Amplatz dilator and Alken guide was removed and the Amplatz sheath and working guidewire were left in place.
After dilation, nephroscopy was performed with a 24F rigid nephroscope. All steps of renal access were monitored under ultrasonography guidance; no fluoroscopy was used. To minimize renal movement of the kidney, extra-abdominal compression by the hand of an assistant was applied during dilation of the tract when dilators met resistance of the renal capsule.
Stones were fragmented by using a pneumatic lithotripter and extracted by grasper. A 12F Foley catheter used as a nephrostomy tube was fixed at the end of the operation. For all the cases, the nephrostomy tube was removed the day after operation, and the ureteral catheter was withdrawn at the second day if the patient had no urine leak, pain, or fever.
Results
Demographic data of the patients are presented in Table 1. The mean stone size was 28.9±6.7mm (17–35 mm). Mean hemoglobin drop was 1.7±0.5 g/dL (0.5–2.2 g/dL), and no patients needed blood transfusion. Mean access time and nephroscopic time were 4.45 minutes (3–10 min) and 45 minutes (20–80 min), respectively. The stone-free rate was 83%, and two patients underwent shockwave lithotripsy (SWL) for some small residual fragments after the surgical procedure. Stone clearance in a 6-year-old girl with bilateral complete staghorn stones was achieved by two sessions of PCNL on the right side and one session on the left side. Mean hospital stay was 3 days (range 2–5 days).
Demographic and Clinical Characteristics of Patients
Prolonged hospitalization in one patient was because of abdominal distention and bowel ileus that was managed conservatively using nasogastric-tube fixation, bowel rest, and antibiotic therapy. No major complications occurred. Only one patient needed ureteral stent insertion because of constant urinary leakage from the nephrostomy tract. This patient underwent transureteral lithotripsy because of small residual fragments that caused obstruction during passage through the ureter.
Discussion
Renal stones are not common in children, but stone formation in children is associated with metabolic disease and anatomic abnormalities that may be led to recurrence in older age. 2,9 PCNL was first applied to the pediatric population in 1980 using adult size instruments. Technologic advancements and refinements in technique have facilitated the successful application of PCNL in this group. 10 Although SWL is a safe procedure, Shokeir and colleagues 11 showed that PCNL is better than SWL for management of 1 to 2 cm renal stones in children, yielding higher stone-free and lower re-treatment rates. Moreover, Onal and associates 12 revealed the safety and efficacy of PCNL in pediatric patients with cystine stones resistant to SWL.
Children who have undergone radiographic examination are potentially at a greater risk of the deleterious effects of radiation exposure than adults. 13 Likewise, fluoroscopy, which is a most used guidance method for all PCNL steps, is associated with the potential deleterious effect of ionizing radiation that is not dose dependent and can be concomitant with genetic mutation. 14
Endourologists made a new modification by using ultrasonography as an alternative modality to fluoroscopy to reduce radiation exposure because of the risk of stone recurrence in children. Using ultrasonography during access was primarily performed in the adult population to reduce the adverse effect of radiation exposure for both patient and surgeon. 15 –17 Penbegul and coworkers 5 presented the efficacy and safety of ultrasonography-guided PCNL for 17 patients with a stone-free rate of 82%. They used a combination of ultrasonography and fluoroscopy in their procedure (ultrasonography during access and fluoroscopy to check the position of the guidewire and to confirm stone clearance).
Basiri and associates 18 reported the preliminary results of totally ultrasonography-guided PCNL with the patient in the flank position in adult patients. The stone-free rate for single calculi and staghorn or multiple stones was 75% and 70%, respectively, and no major complications were observed. Later, Basiri and colleagues 16 presented their limited experience of totally ultrasonography-guided PCNL with the patient in the supine position with comparable outcomes to the standard technique in the adult group.
In this study, we present our initial experiences of totally ultrasound-guided PCNL in pediatric patients in the prone position. We did not use fluoroscopy in any steps, and all the steps including access, insertion of the Amplatz sheath, and checking residual stones were performed by using ultrasonography. In addition, the stone-free rate in our study was 83% without considering other modalities performed after that. Likewise, Penbegul and coworkers 19 performed ultrasonography-guided PCNL in anatomically abnormal kidneys with renal calculi and complete stone clearance was achieved in 13 of 15 patients. In our study, one patient with horseshoe kidney underwent totally ultrasonography-guided PCNL with complete stone clearance.
Frattini and colleagues 20 in 2001 introduced a novel method for dilation of the nephrostomy tract that was named the one-shot method. Ziaee and associates 7 in 2007 depicted the safety and efficacy of the one-stage tract dilation technique for PCNL in 100 consecutive patients with and without a history of open stone surgery in the same side and finally concluded that using this technique is applicable in almost every adult patient. According to the policy for PCNL in our department, all procedures in 10 pediatric patients were performed by using the one-stage tract dilation technique. Recently, Hosseini and coworkers 8 revealed one-shot tract dilation for PCNL in preschool children as a safe and effective method that reduces fluoroscopic time, tract creation, and dilation time; however, surgical success and operative time were not significantly different between using serial metallic dilators and one-stage dilation.
There is no general consensus regarding the size of instruments in pediatric PCNL, and there is some discrepancy in this matter. We think that (as a hypothesis) extraction of staghorn or multiple stones by small-size devices may necessitate multiaccess PCNL; thus, using standard instruments may reduce possible parenchymal damage and create less small particle residue. Ultramini-PCNL using small devices is an effective method for removing low and medium-bulk renal stones in pediatric and adult patients, but further studies should be performed to compare this method and other standard technique. Likewise, feasibility of using this technique for extraction of staghorn stones has not been clearly defined. 21
In 2004, Desai and coworkers 22 revealed that ultrasonography-guided puncture of the pyelocaliceal system and limiting tract dilation to 22F are main points in reducing blood loss, and multiple tracts produced no significant deterioration in renal function. In 2009, Nouralizadeh and colleagues 3 presented an initial report of PCNL using adult size instruments in 20 young children (less than 5 years old) with proper results. Recently, Goyal and colleagues 6 from 2008 to 2012 assessed prospectively some variables of 158 pediatric PCNLs using adult size instruments. In their study, complications were recorded according to the Clinical Research Office of the Endourological Society Clavien score, and they confirmed that PCNL in children using adult instruments is an effective and safe procedure for managing simple as well complex renal calculi. Likewise, their findings revealed that tract size is not an independent risk factor associated with complications. We had no major complication or blood transfusion requirement because of using adult size instruments.
Some limitations of this study are: Small number of cases and retrospective nature of the study; therefore, a prospective study with a large number of cases should be performed. Mobility of the kidney in children is higher than adult patients, so perhaps the kidney moves forward during Amplatz insertion and produces ambiguity in estimating the tract length. At the end of the surgical procedure, evaluation of residual fragments is an important step in PCNL. Irrigation fluid in the pyelocaliceal system and perirenal area may show some degree of echogenicity and mimic the stone appearance during ultrasonography for control of residual stones. Thus, detection of residual fragments solely by using ultrasonography may be not reliable, and this is a major drawback of this technique.
Conclusion
Preliminary results of our experience with totally ultrasonography-guided PCNL for managing of renal calculi in children in a teaching center revealed proper results and an acceptable complication rate compared with the standard technique of PCNL. Likewise, using this technique clearly prevents the radiation hazards. Totally ultrasonography-guided PCNL especially in children necessitates high expertise in the endourologic field, and we recommend that only highly skilled surgeons and those familiar with ultrasonography perform this method for managing renal calculi in pediatric patients.
Footnotes
Acknowledgement
This article was presented at the 12th Asian Congress of Urology in Kish Island, Iran, December 5–9, 2014.
Author Disclosure Statement
No competing financial interests exist.