Feasibility of Totally Tubeless Percutaneous Nephrolithotomy Under the Age of 14 Years: A Randomized Clinical Trial

Introduction

P ercutaneous Nephrolithotomy (PCNL) is a safe procedure in adults and also in children, with 82% to 94% stone-free rate. ^1,2 PCNL in the pediatric population was first described in 1985, by Woodside et al, using standard adult instruments. ³ Concerns about the damage to the kidney parenchyma were reviewed using glomerular filtration rate (GFR) measurement, dimercaptosuccinic acid (DMSA), and diethylene triamine pentaacetic acid (DTPA) renal scan and revealed that renal function improved or stabilized after percutaneous procedure. ^4,5

Very recent systematic reviews and meta-analyses show that tubeless PCNL is an effective and safe procedure in comparison with standard PCNL in the management of uncomplicated renal calculi. It was associated with quicker recovery, less pain, less hospital stay, and acceptable complications in adults. ^6,7 Studies on special group of patients with urinary stone disease, such as those on chronic antiplatelet therapy and cirrhotic patients ⁸ or children, have shown the same findings. ⁹

Totally tubeless technique has been introduced for adult nephrolithotomy about a decade ago and afterward many studies described its applicability in 2/3 of all PCNL surgeries, even in patients who had previous open renal surgery. ^{10 –12} Totally tubeless PCNL is considered as an accepted standard of care for selected cases ¹³ ; furthermore, some authors have reviewed the different techniques of renal drainage after PCNL and conclude that the optimal renal drainage method should be individualized. ¹⁴ Since, there are limited studies reporting that tubeless and totally tubeless PCNL can be applied in children, this study was carried out to examine the safety and effectiveness of totally tubeless PCNL in this group of patients, in a randomized controlled clinical trial.

Materials and Methods

We used a prospective randomized trial study design to provide a comparison between totally tubeless PCNL and standard PCNL in a group of <14-year-old children. After obtaining an approval from the Tehran University of Medical Sciences' ethical committee, in a 15-month period between March 2010 and June 2011, 23 eligible patients were enrolled in the study. The inclusion criteria were age <14 years, presence of renal stone larger than 2.5 cm or renal stone with lesser diameter, and extracorporeal shockwave lithotripsy (SWL) failure. Stone diagnosis was made by sonography or kidney, ureter, and bladder radiograph (KUB) and was confirmed by intravenous urography. Spiral noncontrast enhanced CT scan was used due to contrast sensitivity only in two patients in tubeless and three patients in control group. The exclusion criteria were kidney anomalies, renal failure on admission, and serious bleeding or perforation in the collecting system during the operation.

Preoperatively, patients underwent routine physical examination and lab tests (urine analysis and culture, serum creatinine, and hemoglobin concentration). Patients' characteristics and data were gathered in data-gathering form including age, sex, weight, stone burden, stone location, and so on. Stone location confirmation test routinely was done on call to operation room by means of KUB or ultrasonography instead in case of nonopaque stone.

The procedure was started by ureteral catheter insertion. Then puncture was performed in the prone position by 18-gauge nephrostomy needle, under fluoroscopic guidance the tract was dilated by coaxial serial metallic dilators, an Amplatz sheath up to 28F, and up to 26F Storz nephroscope was used. The stone fragmentation was performed with a pneumatic lithotripter (EMS Swiss lithoclast) and residual stones were extracted with a grasper. At the end of procedure, the randomization envelope was opened by circulating nurse and the patients were assigned to tubeless or control group. Two patients with severe bleeding needed nephrostomy tamponade or pelvicaleceal perforation needed long-time stenting were excluded from the study.

In totally tubeless group both ureteral stent and the working sheath were removed at the end of procedure without placing any nephrostomy tube and patient was transferred from recovery room to ward bearing just a bladder catheter. For the control group as conventional PCNL group, ureteral stent was remained and a nephrostomy tube was placed through the working sheath for 24–48 hours. Postoperative evaluations included physical examination, lab tests (hemoglobin concentration and renal function tests), and imaging (abdominal and pelvic ultrasound and plain abdominal X-ray) were performed in all patients 24–48 hours after surgery, in order to find any complications. The patients were discharged when there was no urine leakage from nephrostomy tract, pain, fever, or hematuria. All patients were examined again one week and one month after the surgery; moreover, sonography was carried out to determine stone clearance. It would consider as successful PCNL, if there was no stone fragment remaining larger than 4 mm at sonography.

At last, analysis of covariance model, t-test, Fisher exact, and Pearson chi-square tests were used for data analysis. The groups were reviewed for these items: operation time, hospitalization period, postoperative analgesic requirement, and complications such as urinary leakage, reoperation, fever, and bleeding. If the difference was not statistically significant in each parameter, we calculated power to find whether it is due to small sample size or not. In the current study, all statistical analyses were calculated using SPSS ver. 15 package program and p<0.05 was considered statistically significant.

Results

The totally tubeless PCNL group (group A) comprised of 13 patients, 10 (77%) men and 3 (23%) women, and the standard PCNL group (group B) comprised of 10 children, 6 (60%) boys and 4 (40%) girls. Patients' characteristics and operation outcomes have been shown in Table 1. In Table 2, stone location and access position were noted.

PCNL was successful in the entire patients in both groups but two (15.3%) patients in totally tubeless group had remnants. It means the overall stone-free rate of study was 91.3%. The two unsuccessful cases with perforation and bleeding stent that was replaced were excluded from the study. Furthermore, in group A, one (7.7%) participant had urinary leakage and needed intervention (ureteral stenting), while in the standard group, one (10%) patient had leakage but did not require another surgery. No intraoperative and postoperative transfusion was needed in either group due to nonsignificant blood loss during or after the operation, or postoperative hemoglobin drop. The cases who experienced fever after surgery were controlled with intravenous antibiotics and oral antipyretic. There was no other significant complication in both groups.

Generally, patients' age, weight, stone burden, stone location, operative time, hemoglobin drop, transfusion rates, complications, and stone-free rates were not statistically different between the two groups, whereas hospital stay and need for analgesics were significantly lower in the totally tubeless group, as shown in Table 1 (p<0.001). We also calculated power of the study (1−α) for hemoglobin drop and operation time that was 0.29 and 0.17, respectively.

Discussion

Many studies conducted in adults have confirmed that totally tubeless PCNL is safe and feasible in the management of kidney stone in adults. ^{15 –20} A recent meta-analysis on 14 randomized controlled trials in adults comparing 776 subjects showed that there were statistically significant differences in hospital stay, postoperative analgesic requirement, and urine leakage between tubeless and standard PCNL. Between these two methods, no statistically significant differences were found in stone-free rate, postoperative fever, and blood transfusion. ⁶

There are reports of PCNL being carried out safely in children of various ages, even infants. Simultaneous bilateral PCNL was conducted in five patients for bilateral renal stones. The mean age of the patients was 6.28 years (range 0.75–15) and the mean renal stone burden was 19 mm (range 11–22), smaller than what we observed in our study. ²¹ Zilberman et al describe that tubeless PCNL appears to be safe in children and also in the following circumstances—uneventful procedures, simultaneous bilateral procedures, supracostal access, anatomical anomalous kidneys, and in obese patients. They also conclude that nephrostomy tube placement should still be considered in certain cases such as those with more than two nephrostomy access tracts, those requiring a second look, and those with intraoperative complications, such as significant bleeding or collecting system perforation. The mean stone-free rate for tubeless PCNL in their study was 89%. ²²

Recently, Bilen et al retrospectively analyzed the outcomes of tubeless mini PCNL in total of 28 renal units in infants and preschool children, and compared them with age-matched controls who underwent nephrostomy drainage. Tubeless PCNL was observed to be a safe option for selected children with stone disease, and hospitalization was shorter than standard group, 4.9 (range 3–14) versus 3.1 days (2–6) ²³ ; moreover, hemorrhage has been the most prevalent disadvantage of this technique (0%–30%) regardless of the stone and instrument size. ²⁴ In fact, in their technique (tubeless PCNL) that is different from ours (totally tubeless PCNL) usualy a ureteral stent is left in place for 1–2 days. Totally tubeless PCNL as was described in previous published data by authors relies on natural drainage abilities of ureter when the peristalsis is not suppressed by stenting. ^15,25,26

Clinical trials on infants and small children showed no difference in complications, stone-free rates, or retreatment rates among children undergoing conventional percutaneous procedures via different size access tracts, even using adult size instruments. ^2,27,28 According to these findings, in pediatric patients the use of the same instruments and technique as in adults may carry no increased risk of possible morbidity or need of blood transfusion. So, we decided to use adult size instruments to conduct the current study.

In a randomized clinical trial in adults, Crook et al ¹³ reported mean stone size in conventional group 21.6 versus 17.5 mm in tubeless group and hemoglobin change 2.03 versus 1.18 gm/dL. Mean length of stay was 3.4 versus 2.3 days (p<0.05), also. There were no differences in hemorrhage, infection, and serum parameters. The most common reported complications of PCNL include postoperative fever in 30% of patients and transfusion in 0% to 23.9% of patients. ^{9,24,29 –31} In the current study, we observed the same rate for fever in standard group but a lower rate (15.5%) in the totally tubeless group. Transfusion rate was 0% in the both groups. In addition, we found that not only pain but also hospital stay after totally tubeless PCNL is significantly less than standard method (p<0.001). But, operation time and hemoglobin drop were not significantly different (p=0.5 and p=0.17, respectively). In these parameters, we calculate the power of study and find that it is due to a small sample size (power=17% and 29%, respectively). As this study yielded that totally tubeless PCNL could be carried out in children, authors have a plan to perform a larger study in cooperation with pediatric referral centers nationwide to find a definite result, although we found this technique to be at least equal in major parameters.

Although there are limited studies reporting that tubeless and totally tubeless PCNL can be safely applied in pediatric patients, ³² our experience on adults since 2004 shows that totally tubeless PCNL is a safe and effective procedure, even in renal anomalies with a moderate to large stone. ²⁵ The hospitalization and analgesia requirements are less and the return to normal activities is faster with this technique. ^15,26 In addition, it has been shown through randomized controlled trials that totally tubeless PCNL is safe and well tolerated in selected cases associated with decreases in length of hospital stay and postoperative pain. So it maybe considered as reasonable treatment option for patients with no major intraoperative bleeding or calyceal perforation ^{16 –18} ; but a randomized controlled trial was at least rare in children to support the idea. In this study we found the same results as in adults. According to our findings, it maybe concluded that total tubeless PCNL in children has complication rates that are comparable with standard method, although more studies with more participants are advocated.