Abstract
Introduction:
In this study, we aimed to evaluate the safety and efficacy of the percutaneous nephrolithotomy procedure performed with adult-sized instruments in pediatric cases with staghorn kidney stone.
Methods:
We retrospectively evaluated the efficacy and safety of 94 percutaneous nephrolithotomy procedures performed during 15 years in a single center for 82 pediatric patients with staghorn calculi using adult-sized instruments (24-Fr nephroscope). Stone free status was defined as complete clearance of the stones or the presence of insignificant residual stones of <3 mm in diameter.
Results:
The mean age was 108 ± 53 months (range, 14–180 months). There were 39 patients (48%) with complete staghorn stones and 43 cases (52%) with partial staghorn. We fulfilled 91.4% of operations through a single access. The stone free rate was 86.6% after one percutaneous nephrolithotomy session. In total, seven patients referred for shock wave lithotripsy and four cases were scheduled for the second percutaneous nephrolithotomy session. Fever occurred in 18 patients (21%) and bleeding requiring transfusion in four children (5%). Prolonged leakage from nephrostomy site requiring anesthesia for double J stent placement occurred in one patient. No grade IV or V Clavien complication occurred.
Conclusion:
The success rate and complications of percutaneous nephrolithotomy with adult-size instruments in pediatric patients are acceptable.
Introduction
It is estimated that 5%–10% of the world population would suffer from renal stones during their lifetime, among them children account for only 2%–3% of the cases. The incidence of pediatric renal stones is higher in certain developing countries.1,2 Staghorn calculus is defined as a stone that occupies a large portion of the pelvicalyceal system. 3 A partial or complete staghorn is defined as a calculus that fills the pelvicalyceal system partly or entirely; however, the term “partial” or “complete” staghorn has no definite specific volume or size. 4 The gold standard treatment for staghorn calculus is percutaneous nephrolithotomy (PCNL) in both adults and children. Since the first report of PCNL for pediatric renal stones 4 in 1985, developments in surgical instruments and advances made in surgical techniques have increased the safety and efficacy of this surgical method in children. 5 Although PCNL has been accepted for pediatric cases worldwide, there are still concerns with this technique in children including the instrument size, hypothermia, acute complications, the less-robust collecting system, and its possible long-term effects on the kidney function.6,7
In this study, we aimed to evaluate the safety and efficacy of the PCNL procedure in pediatric cases performed with adult instruments.
Methods
We retrospectively evaluated the efficacy and safety of 94 PCNL procedures performed in a single center during 15 years for 82 pediatric patients, aged from 14 months to 15 years old, with staghorn calculi. All procedures were performed between January 2002 and March 2017 in Labbafinejad Medical Center, Tehran, Iran.
All patients were evaluated by intravenous urography (IVU) or non-contrast computed tomography (CT). We evaluated some patients by non-contrast CT. In patients referred to our center with IVU, we did not perform CT scan due to radiation risk.
After routine preoperative evaluation, all patients with negative urine culture results received intravenous antibiotic prophylaxis with a second-generation cephalosporin prior to anesthesia. Under general anesthesia, we inserted a 5-Fr open-ended ureteral catheter up to the kidney using cystoscopy in the lithotomy position. Patients were then placed in the prone position with pressure sites and chest support. We instilled contrast media under fluoroscopy to visualize the collecting system to select the appropriate calyx for puncture. Using an 18-G Chiba needle, we accessed the calyx and placed a hydrophilic 0.035 guide wire to the calyceal system. We dilated the tract with a 9-Fr facial dilator and inserted the metal antenna guide over the guide wire. Then we dilated the nephrostomy tract up to 26 or 28 Fr using one-shot technique. After placing a working sheath over the Amplatz dilator to the collecting system, a rigid 24-Fr nephroscope (Richard Wolf® without Sheath) was utilized to perform the stone fragmentation with a pneumatic lithotripter. Stone extraction was done using grasping forceps. At the end of the surgery, a 14-Fr nephrostomy tube was fixed for 24 h. The ureteral catheter and the Foley urethral catheter were removed 72 h after surgery, and during this period, we continued prophylactic antibiotic with second-generation cephalosporins. At the same day, we checked the blood cell count, ionogram, and creatinine concentration. On the first postoperative day, kidney, ureter, and bladder (KUB) X-ray was routinely performed in all patients for evaluation of possible stone remnants. Patients with non-opaque stones were followed up by non-contrast CT scan and another patient was evaluated by ultrasonography and KUB due to radiation risk in pediatric cases within 1 month of surgery. Stone-free status was defined as complete clearance of the stones or the presence of insignificant residual stones of <3 mm in diameter.
In this study, we collected and analyzed these variables: history of previous stone surgery, stone burden and stone location, perioperative and postoperative data including duration of operation, renal access, stone free rate (SFR), blood transfusion, and complications using Clavien grading system.
Statistical analysis
We inserted all data in the SPSS 22 software IBM. Data are presented as mean and standard deviation, and the frequency of categorical variables are presented as count (percent). We used Student’s t-test to compare means between girls and boys. Furthermore, chi-square test was used for comparing frequencies between two gender groups.
Results
During the study period, 94 PCNL procedures were conducted in our institute on 82 children under 15 years with staghorn (49 boys and 33 girls; Table 1). The patients’ mean age was 108 ± 53 months (range, 14–180 months). Complete staghorn was detected in 39 patients (47.6%), whereas partial staghorn was present in 43 children (52%).
Data characteristics of patients (preoperative and postoperative).
PCNL: percutaneous nephrolithotomy; SWL: shock wave lithotripsy; SD: standard deviation.
Data presented as mean ± SD or count (percent).
The mean operating time was 118 min (range, 50–170 min). The majority of cases (74 cases, 91.4%) were performed with a single tract, while seven children (8.6%) needed two tracts and we did not use more than two accesses in any patient. Transfusion rate was higher in those with two accesses (28.6%) compared with 13.7%; however, this difference was not statistically significant (p = 0.29). The most common puncture location was through the lower pole calyx (86.6%) followed by middle calyx in 10. Supracostal access to the upper pole calyx was used primarily in one patient while in four patients, those who needed two accesses, the second access was performed supracostally to the upper pole calyx (10.4%).
The SFR was 86.6% after one PCNL session. Seven patients referred for shock wave lithotripsy (SWL) and four cases were scheduled for the second PCNL session.
The most common complication was postoperative fever (18 cases) for which a change in the antibiotic regimen was required in eight patients (Table 2). Fever resolved within 72 h in all cases. None of the children developed urosepsis and none required intensive care postoperatively. Severe bleeding requiring transfusion occurred in four cases (5%) and the mean hemoglobin drop was 1.9 g/dL (range, 0.1–4.6 g/dL).
Complications after surgery using Clavien classification.
Excluding cases classified in grade II.
Prolonged urinary leakage from the nephrostomy site occurred in one patient and the leakage was cured after double J stent insertion. Moreover, one child developed delayed hematuria which was managed with conservative treatment. No grade IV or V complication occurred.
We compared data between girls and boys and observed no significant difference regarding intraoperative data as well as postoperative complications between them. Among patients with unilateral stone, most boys (70.7%) had stone in the left kidney, whereas 42.3% of girls had left-sided stone (p = 0.02).
Discussion
The most severe form of renal stones is staghorn calculi. The treatment of this type of urolithiasis is a challenge for urologists. This problematic situation is more complicated in pediatric patients because of the small size of kidneys, large equipment size, and related complications. In this study, SFR in one session of PCNL surgery was about 86.6%. Similar findings have been reported by other research groups. Some published studies on primary PCNL monotherapy for the treatment of staghorn calculi reported that the overall stone-free rate is about 60%–85%.8–10 On the other hand, some studies have reported higher success rates for PCNL in children with staghorn stones compared to our study, reaching up to 90%.6,11 The higher success rates of some studies can be explained by two reasons; first, in some studies with a higher success rate, the majority of surgeries were performed with the multiple access technique. Multiple access PCNL can increase the SFR, but this is just one side of the coin. On the other side, use of multiple access tracts may increase complications, especially bleeding. Desai et al. 12 reported their experience with 50 patients with staghorn or complex kidney stones that showed only in 39% of cases they could clear stones through one access and they mentioned that the number of access tracts is the most significant factor that is associated with hemoglobin drop (p < 0.0001). We were able to remove stones in 95% of occasions using a single access and the mean hemoglobin drop (1.1 g/dL) was lower than what is reported by Desai et al. 12 (1.9 g/dL). Meanwhile, they were using 14-Fr nephroscope and 20- to 24-Fr Amplatz sheath, whereas we used 24-Fr nephroscope and 26- or 28-Fr sheath. Although at the first glance it seems that in the pediatric age group smaller size nephroscope will be associated with lower rate of bleeding, it should be mentioned that as it is observed in Desai report, in most cases more than one access will be required that itself was associated with higher rate of bleeding. 12 Furthermore, in our series, we fulfilled most operations with one subcostal access. It is important to know that when the second access will be required, it will be usually supracostal and may increase the rate of complication. As a conclusion we think although the larger size instrument may be a risk of renal injury, it is associated with better vision, irrigation, and stone extraction as well as faster operation and less necessity for a second or third access to a small child’s kidney.
In our patients, the most common complication was postoperative fever. In all cases, fever resolved within 12–72 h of PCNL and postoperative sepsis did not occur in any patient. This result is compatible with some previous studies. In the study by Kapoor et al. 13 and the series by Gonen et al., 10 postoperative fever occurred in 43.3% and 30% of children, respectively. The cause of fever is urinary tract infection due to the high incidence of infectious stones in children; 10 however, it should be mentioned that in many cases, post PCNL fever is not a consequence of active infection. 14
Previous studies have reported a 1.96%–3.4% incidence of renal arteriovenous fistula and pseudoaneurysm requiring angioembolization following PCNL in staghorn calculi in pediatric patients. 8 In this study, delayed hematuria developed in only one case that resolved with conservative treatment. Angioembolization was not required in any patient. Taken together, it seems that a multiple access tract increases the risk of renal pseudoaneurysms or arteriovenous fistulas. In our study, in most patients, PCNL was performed through a single access tract (91%).
We should acknowledge that the main limitation of our study was that data are collected retrospectively that may affect the study quality.
Conclusion
PCNL can be used as a safe and effective treatment modality in children with staghorn stones. The complications and SFR of PCNL with adult-sized instruments in pediatric patients are acceptable.
Footnotes
Author contributions
A.N. contributed to project development, and data collection and management. H.P. contributed to data analysis, and manuscript writing and editing. A.B. contributed to project development. M.H. Radfar contributed to project development. B.N. contributed to project development, data analysis, and manuscript writing and editing. B.S. contributed to data collection and management, and data analysis. A.V. contributed to data collection and management. R.V. contributed to data collection and management. M.H. Ramezani contributed to data collection and management.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Informed consent
Informed consent was obtained from all individual participants included in the study.
Research involving human participants
All procedures performed in the study that involved human participants were approved by the Ethics Committee of the Urology and Nephrology Research Center (UNRC) at the Shahid Beheshti University of Medical Sciences and were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
