Efficacy and Safety of Percutaneous Nephrolithotomy in Children with Previous Renal Stone Operations

Abstract

Purpose:

To determine the impact of open pyelolithotomy or nephrolithotomy on the results and complications of subsequent percutaneous nephrolithotomy (PCNL) in children.

Patients and Methods:

We retrospectively reviewed the files of 121 children with 135 renal units (RUs) who underwent PCNL between February 2008 and October 2014. We compared RUs with no previous intervention (group 1, 87 RUs) with those that had preceding open pyelolithotomy or nephrolithotomy (group 2, 48 RUs). The demographic characteristics, mean operative time, mean fluoroscopy time, mean hemoglobin changes, number of percutaneous accesses, analgesic requirement, mean hospitalization time, stone-free rate, and complications were all reported and compared.

Results:

The study included 135 RUs in 121 children (74 boys and 47 girls) who underwent PCNL. No statistical differences were detected between the two groups in terms of age, sex, stone size, stone laterality, and stone opacity. Mean operative time, mean fluoroscopy time, mean hemoglobin change, number of percutaneous accesses, supracostal access, analgesic requirement, and hospitalization stay were similar in each group (P>0.05). The stone-free rate in group 1 was higher than that in group 2 (81.61% vs 79.17%). This was not statistically significant (P>0.05), however.

Conclusion:

Previous open pyelolithotomy or nephrolithotomy does not affect the efficacy and morbidity of subsequent PCNL in pediatric patients.

Introduction

Pediatric nephrolithiasis is an important health problem that has increased in incidence, more likely because of the change in dietary habits and lifestyle. One of the contributing factors leading to stone disease is a diet that is rich in sodium and carbohydrates.^1,2 There is a worldwide variation in the incidence of pediatric urolithiasis, and it varies from 5% to 15% in developing countries in comparison with 1% to 5% in developed countries.³ Stone management in pediatrics has specific issues. This may be associated with underlying metabolic or anatomic abnormalities that increase stone recurrence. These patients need both metabolic workup and strict follow-up throughout their life span.

Over the last two decades, surgical management of pediatric urolithiasis has evolved significantly. Since the advent of extracorporeal shockwave lithotripsy (SWL) in the 1980s, it is currently the modality of choice for managing most upper urinary tract stones.⁴ SWL limitations are: The functional long-term effects on developing kidneys and adjacent structures have not yet been determined, ineffective for large stone burden, and there is a need for multiple sessions under anesthesia.⁵

Since Woodside and associates⁶ reported the first pediatric percutaneous nephrolithotomy (PCNL) in 1985, there have been many technologic improvements, instruments miniaturization, and mounting endourologic experience. In the present era, PCNL is a well-established minimally invasive technique for management of pediatric nephrolithiasis with better stone clearance and faster recovery compared with SWL or open surgery. The disadvantages of PCNL in children are potential renal damage, radiation exposure, and the risks of major complications, including sepsis and bleeding.

Recent studies attest to the safety of PCNL even in children below school age.^3,7 PCNL is the treatment modality of choice for patients with large, hard, complex, multiple, and staghorn renal stones. It allows complete stone clearance, and it is associated with a lower requirement of auxiliary procedures with minimal morbidity in a single sitting.^8
–10

Pediatric urolithiasis carries the risk of lifelong recurrence with an overall 5-year recurrence rate of 55%,^11,12 because it may be associated with anatomic anomalies or metabolic disorders. Previous open stone surgery results in perirenal scarring and distortion of the pelvicaliceal (PCS) anatomy. These changes may affect the outcomes of subsequent PCNL procedures.¹³ The impact of previous open stone surgery on success rate and morbidity of subsequent PCNL in adults has been studied by several authors.^14
–16 To our knowledge, there is a relative lack of studies determining the effect of previous open stone surgery on subsequent PCNL in pediatrics. The aim of our study is to evaluate the outcomes and complications of PCNL in children with previous open surgery.

Patients and Methods

We retrospectively reviewed the data of 121 children with 135 renal units (RUs) who underwent PCNL between February 2008 and October 2014. RUs were categorized as group 1 (87 RUs with no previous intervention) and group 2 (48 RUs with previous open pyelolithotomy or nephrolithotomy). Preoperative evaluation included urine analysis, urine culture and sensitivity, blood urea, serum creatinine, complete blood cell count, coagulation tests, radiography of the kidneys, ureters, and bladder (KUB), pelviabdominal ultrasonography, and noncontrast CT (NCCT).

The demographic characteristics, mean operative time, mean fluoroscopy time, mean hemoglobin changes, number of percutaneous access, number of supracostal accesses, analgesic requirement, mean hospitalization time, stone-free rate, and complications were all reported and compared. We used the modified Clavien system to grade perioperative complications. The current study was approved by the local ethics committee.

Surgical technique

All PCNLs were performed under general anesthesia. A prophylactic broad-spectrum antibiotic was administered intravenously. A ureteral catheter (5F) was introduced under fluoroscopy with the patient in the lithotomy position. PCNL access was achieved with the patient in the prone position. The puncture was made using an 18-gauge access needle under fluoroscopic control after retrograde opacification of the collecting system via the ureteral catheter.

Tract dilation was performed using serial Amplatz dilators. The tract was dilated up to 19F in preschool children (younger than 6 years) and up to 24F in older children. A 12F Storz rigid nephroscope was used in preschool children and a 24F Storz rigid nephroscope was used without its own outer sheath in older children. Stone fragmentation was accomplished with a pneumatic lithotripsy. Complete stone clearance was confirmed by the nephroscope and fluoroscopy.

An adequate size nephrostomy tube was inserted in the tract. If there was intractable pain, ketorolac 0.5–1 mg/kg would be administered intramuscularly. The nephrostomy tube was clamped 24 to 48 hours after the procedure and was removed if there was no pain or fever. Before discharge from the hospital, KUB radiography was performed to determine stone clearance.

Follow-up

On follow-up, all children were evaluated by urine analysis, KUB radiography, ultrasonography, and NCCT in selected cases after a month, and the status was evaluated by KUB radiography and ultrasonography every 3 months during the first year, and every 6 months thereafter. The child was considered either stone free or having residual stones (if there were radiologic signs of persistent stone fragments irrespective of size).

Statistical analysis was performed using SPSS, version 19 (SPSS Inc, IBM, Armonk, NY). For quantitative data, both the means and the standard deviation were calculated. The independent t test was used to compare the study groups. For qualitative data, the number and percent distribution was calculated, and chi square was used as a test of significance. Significance was adopted at P<0.05.

Results

The study included 135 RUs in 121 children (74 boys and 47 girls) who were all treated by PCNL. No significant differences were detected between the two groups in terms of age, sex, stone size, stone laterality, and stone opacity. Patient demographics and stone characteristics are listed in Table 1. According to Table 2, there were no statistically significant differences between the two groups in terms of mean operative time, mean fluoroscopy time, hemoglobin change, number of percutaneous accesses, supracostal access, analgesic requirement, and hospitalization stay. The stone-free rate in group 1 was higher than that in group 2 (81.61% vs 79.17%). This was not statistically significant (P>0.05), however. These percentages increased to 94.25% and 91.7% with adjunctive SWL (15 patients) and ureteroscopy (2 patients) in group 1 and group 2, respectively.

Table 1.

Demographic Profile of Children in the Two Groups

	Group 1	Group 2	P value
Patients	81	40
Renal units	87	48
Age (years)±SD (range)	7.3±3.5 (2–15)	7.9±4.2 (2–16)	0.388
Male:female	49:32	27:13	0.696
Laterality of stone			0.368
Rt	39	26
Lt	48	22
Stone size (mm)	31±3.6	32±2.9	0.102
Stone opacity			0.578
Opaque	78	41
Radiolucent	9	7
Stone location			0.749
Pelvic	32	15
Caliceal	15	7
Pelvicaliceal	37	25
Staghorn	3	1

SD=standard deviation.

Table 2.

Perioperative and Postoperative Profile of the Two Groups

	Group 1	Group 2	P value
Mean operative time (min)	105±38.7	113±40.3	0.259
Mean fluoroscopy time (min)	7.34±5.61	7.96±4.64	0.515
Mean hemoglobin change (mg/dL)	0.71±0.54	0.84±0.62	0.206
One access	81 (93.1%)	44 (91.7%)	0.743
Two access	6 (6.9%)	4 (8.3%)
Supracostal access	5 (5.7%)	2 (4.2%)	1.000
Ketorolac requirement (mg)	200±50	185±60	0.120
Mean hospital stay (days)	3.3±1.6	3.6±0.6	0.213
Stone-free rate	71 (81.61%)	38 (79.17%)	0.820

As for intraoperative and postoperative complications, no difference was observed between the two groups according to the modified-Clavien classification system (Table 3). Because the complication rates were low in both groups, statistical analysis could not be performed. A total of 33 complications were recorded in group 1 (37.9%) and 17 in group 2 (35.4%). The most common complication was bleeding managed by intravenous fluid without the need for blood transfusion (grade I). It was recorded in 10 (11.5%) patients and 5 (10.4%) in group 1 and group 2, respectively. Bleeding managed by blood transfusion was reported in five (5.7%) patients and two (4.2%) in group 1 and group 2, respectively. In six of seven patients who needed blood transfusion, the tract was dilated up to 24F, and in one patient, it was dilated up to 19F. Only one patient in group 1 had hydrothorax (grade III) and was treated by chest tube.

Table 3.

Complications of Percutaneous Nephrolithotomy According to Clavien Classification

	Group 1	Group 2	Clavien grade
Urinary leakage managed by watchful waiting	7 (8%)	4 (8.3%)	I
Bleeding managed by IV fluid (no blood transfusion)	10 (11.5%)	5 (10.4%)	I
Infections managed by antibiotics UTI, pneumonia	7 (8%)	5 (10.4%)	II
Bleeding managed by blood transfusion	5 (5.7%)	2 (4.2%)	II
Urine leakage necessitating ureteral stent pacement	3 (3.4%)	1 (2%)	III
Hydrothorax ncessitating chest tube	1 (1.1%)	-	III

IV=intravenous; UTI=urinary tract infection.

Of the 135 procedures, stone chemical analysis was available in 123 patients (79 in group 1 and 44 in group 2), and of those, calcium oxalate was detected in 49 (31 in group 1 and 18 in group 2), struvite in 28 (21 in group 1 and 7 in group 2), uric acid in 15 (9 in group 1 and 6 in group 2), cystine in 9 (6 in group 1 and 3 in group 2), and mixed in the rest (12 in group 1 and 10 in group 2).

Discussion

Notwithstanding the rarity of pediatric urolithiasis in developed countries (1% to 5% of all urinary tract stones), it is common in developing countries, particularly stone belt regions, such as Turkey and Pakistan (30% of all urinary tract stones).¹⁷ Fernström and Johansson¹⁸ were the first to report PCNL in adults in 1976, and Woodside and colleagues⁶ were the first to report PCNL in pediatrics in 1985. At present, there is growing experience in adult PCNL, technology development, and miniaturization of instruments. These factors led to the establishment of PCNL as a safe and effective modality for the management of pediatric nephrolithiasis.

PCNL outcome is influenced by several factors, such as stone burden, location, and renal anatomy. Stone-free rate after PCNL has been reported between 73% and 96%. Although pediatric PCNL is difficult because of the small sized kidneys and large instruments, the success rate is similar among adults and the pediatric population.^19
–21 At present, pediatric PCNL is indicated in children with a renal stone >2 cm or with staghorn stones, lower caliceal stones >1 cm, failed SWL, or in the presence of anatomic anomalies.²²

Urolithiasis in childhood is usually associated with anatomic abnormalities, metabolic disorder, or dietary factors that could be a cause of a high recurrence rate. Therefore, many children who had previous open pyelolithotomy or nephrolithotomy may have recurrent stones, and they need subsequent PCNL for stone removal. Previous open stone surgery may affect subsequent PCNL with more difficulty because of retroperitoneal fibrosis, or may be helpful because the fibrosis restricts renal mobility.¹²

A number of studies compared the outcomes of PCNL in adult patients with and without previous operations. This comparison was first reported in pediatrics by Onal and coworkers.²³ They concluded that previous open stone operations do not affect the outcomes of subsequent PCNL on the same kidney. In a recently published study, Telli and associates²⁴ compared the results of primary PCNL of the kidneys and PCNL after preceding open surgery, PCNL, and SWL. They reported that there were no significant differences of PCNL in terms of the success rate and complications between the study groups.

Studies investigating the effects of earlier open surgery on subsequent PCNL in adults reported different results. While two series^25,26 reported higher complication rates and a lower stone-free rate in patients who had previous open surgery than those who had primary PCNL, others^{13
–15,27,28} found no differences in morbidity and success rates.

The current study showed no significant differences between both groups in terms of age, sex, stone laterality, and stone burden. Similar findings were reported by Telli and coworkers,²⁴ but in the study by Onal and colleagues,²³ there was a significantly higher age in children with previous surgery because of the lack of experience and facilities when they were young to perform PCNL.

Preceding open stone surgery induces retroperitoneal scarring and distortion of the PCS that may cause difficulty in puncturing the PCS. In the study by Margel and associates,¹³ the number of renal entries were 1.2±1.1 vs 2.3±1.9 in primary and secondary PCNL, respectively. Similar difficulties at puncturing the PCS were reported by Gupta and colleagues¹⁴ and Vivile²⁶ who had more attempts to enter the PCS in previously operated patients in comparison with primary cases.

We did not experience difficulties in children with earlier open surgery during the PCS puncture. Similar to our study, Onal and associates²³ and Sofikerim and colleagues¹⁵ concluded that the PCS can be punctured easily in previously operated patients. In our opinion, retroperitoneal fibrosis from previous surgery restricts renal movement during breathing, which facilitates the PCS entry.

In our study, tract dilation was performed using serial Amplatz dilators in all patients. The serial Amplatz dilators were effective, even in recurrent cases with perirenal scarring because their small tip could be advanced through the preceding smaller dilated tract. Similar observations were reported by Onal and coworkers²³ and Sofikerim and associates.¹⁵ On the other hand, Gupta and colleagues¹⁴ and Kurtulus and coworkers²⁹ described difficulty during tract dilation in patients with previous surgery.

Supracostal approaches have been described to avoid the fibrosis in patients with previous operations.²⁸ In our study, the approach was based on stone location and the PCS anatomy on NCCT. The last decision, however, was based on retrograde pyelography intraoperatively. Supracostal approaches were performed in five patients (5.7%) vs two (4.2%) of group 1 and group 2, respectively. Also, Onal and associates²³ and Sofikerim and colleagues¹⁵ believed that the site of the PCS approach should be based on stone location rather than on the issue of perirenal fibrosis. In this study, more than one access was performed in six patients (6.9%) vs four (8.3%) of group 1 and group 2, respectively. The rate was higher for children with preceding open stone operations, but was not statistically significant.

The tract size and use of adult instruments in pediatric PCNL is an important concern and is still in evolution. This is related to the impact of tract size on small pediatric kidneys and the extent of renal parenchymal injury. While a number of studies^7,8,30
–32 reported that the use of adult instruments during pediatric PCNL was safe and effective, others reported a higher complication rate.^10,33

–36

In our study, tract size was based on the age of the patient and was not related to whether there was a preceding open surgical procedure or not. We dilated the tract up to a 19F in preschool children (younger than 6 years old) and up to 24F in older children.

Both the mean operative and hospitalization times are among the parameters reflecting difficulty and morbidity of the procedure. In this study, there was no significant difference between the two groups in terms of the mean operative and hospitalization times (Table 2). Onal and associates²³ and Telli and coworkers²⁴ reported similar findings in pediatrics. In adult studies, Gupta and colleagues¹⁴ and Sofikerim and associates¹⁵ reported the same findings. Margel and coworkers¹³ and Tugcu and colleagues³⁷ found that the average operative time was significantly higher in patients with preceding open stone surgery.

In the literature, the reported stone-free rate after PCNL in pediatrics ranges from 68% to 100%.³ In our study, the stone-free rate in group 1 was higher than that in group 2 (81.61% vs 79.17%). This was not statistically significant (P>0.05), however. These percentages increased to 94.25% and 91.7% with adjunctive SWL (15 patients) and ureteroscopy (2 patients) in group 1 and group 2, respectively.

PCNL complications in children are quite similar to those in adults. Complication rates in the adult population are 29% to 44%.³⁸ Zeren and coworkers³³ reported complication rates at 24% for the need for transfusion and 30% for transient fever during PCNL in children.

Concerns regarding long-term effects of PCNL on the pediatric kidney are lacking. Dawaba and associates⁹ found no new renal scarring and an improved overall renal function on a long-term follow-up after PCNL in the pediatric population. In our study, complication rates were 37% (50 RUs of 135)—33 (37.9%) complications in group 1 and 17 (35.4%) in group 2. Most of the complications were grade I or grade II 45 RUs (33.3%). Bleeding managed by intravenous fluid without the need for blood transfusion was the most common complication (10 patients [11.5%] and 5 [10.4%] in group 1 and group 2, respectively). Hydrothorax (grade III) managed by chest tube was reported in one patient (group 1).

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

References

Tellaloglu

, Ander

. Stones in children. Turk J Pediatr, 1984; 26:51–60.

Srivastava

, Alon

. Urolithiasis in adolescent children. Adolesc Med Clin, 2005; 16:87–109.

Mahmud

, Zaidi

. Percutaneous nephrolithotomy in children before school age: Experience of a Pakistani centre. BJU Int, 2004; 94:1352–1354.

Lottmann

, Traxer

, Archambaud

, Mercier-Pageyral

. Monotherapy extracorporeal shock wave lithotripsy for the treatment of staghorn calculi in children. J Urol, 2001; 165:2324–2327.

Resorlu

, Unsal

, Tepeler

, et al. Comparison of retrograde intrarenal surgery and mini-percutaneous nephrolithotomy in children with moderate-size kidney stones: Results of multi-institutional analysis. Urology, 2012; 80:519–523.

Woodside

, Stevens

, Stark

, et al. Percutaneous stone removal in children. J Urol, 1985; 134:1166–1167.

Nouralizadeh

, Basiri

, Javaherforooshzadeh

, et al. Experience of percutaneous nephrolithotomy using adult-size instruments in children less than 5 years old. J Pediatr Urol, 2009; 5:351–354.

Bilen

, Kocak

, Kitirci

, et al. Percutaneous nephrolithotomy in children: Lessons learned in 5 years at a single institution. J Urol, 2007; 177:1867–1871.

Dawaba

, Shokeir

, Hafez

, et al. Percutaneous nephrolithotomy in children: Early and late anatomical and functional results. J Urol, 2004; 172:1078–1081.

10.

Unsal

, Resorlu

, Kara

, et al. Safety and efficacy of percutaneous nephrolithotomy in infants, preschool age, and older children with different sizes of instruments. Urology, 2010; 76:247–252.

11.

Smaldone

, Docimo

, Ost

. Contemporary surgical management of pediatric urolithiasis. Urol Clin North Am, 2010; 37:253–267.

12.

Lao

, Kogan

, White

, Feustel

. High recurrence rate at 5-year follow-up in children after upper urinary tract stone surgery. J Urol, 2014; 191:440–444.

13.

Margel

, Lifshitz

, Kugel

, et al. Percutaneous nephrolithotomy in patients who previously underwent open nephrolithotomy. J Endourol, 2005; 19:1161–1164.

14.

Gupta

, Gupta

, Singh

, et al. PCNL—A comparative study in nonoperated and in previously operated (open nephrolithotomy/pyelolithotomy) patients—A single-surgeon experience. Int Braz J Urol., 2011; 37:739–744.

15.

Sofikerim

, Demirci

, Gulmez

, Karacagil

. Does previous open nephrolithotomy affect the outcome of percutaneous nephrolithotomy?. J Endourol, 2007; 21:401–403.

16.

Falahatkar

, Panahandeh

, Ashoori

. What is the difference between percutaneous nephrolithotomy in patients with and without previous open renal surgery?. J Endourol, 2009; 23:1107–1110.

17.

Lahme

. Shockwave lithotripsy and endourological stone treatment in children. Urol Res, 2006; 34:112–117.

18.

Fernström

, Johansson

. Percutaneous pyelolithotomy. A new extraction technique. Scand J Urol Nephrol, 1976; 10:257–259.

19.

Özden

, Şahin

, Tan

, et al. Percutaneous renal surgery in children with complex stones. J Pediatr Urol, 2008; 4:295–298.

20.

Erdenetsesteg

, Manohar

, Singh

, Desai

. Endourological management of pediatric urolithiasis: Proposed clinical guidelines. J Endourol, 2006; 20:737–748.

21.

Kapoor

, Solanki

, Singhania

, et al. Safety and efficacy of percutaneous nephrolithotomy in the pediatric population. J Endourol, 2008; 22:637–640.

22.

Turk

, Knoll

, Petrik

, et al. EAU guidelines on urolithiasis. European Association of Urology. 2013. Available at: uroweb.org. Accessed: June 23, 2015 .

23.

Onal

, Gevher

, Argun

, et al. Does previous open nephrolithotomy affect the outcomes and complications of percutaneous nephrolithotomy in children?. J Pediatr Urol, 2014; 10:730–736.

24.

Telli

, Haciyev

, Karimov

, Sarici

, Karakan

, Ozgur

et al. Does previous stone treatment in children generate a disadvantage or just the opposite?. Urolithiasis, 2015; 43:121–145.

25.

Jones

, Russell

, Kellett

, Wickham

. The changing practice of percutaneous stone surgery: Review of 1000 cases 1981–1988. Br J Urol, 1990; 66:1–5.

26.

Vivile

. Percutaneous nephrolithotomy: Personal experience in 100 cases. J Urol (Paris), 1987; 93:253–258.

27.

Basiri

, Karrami

, Moghaddam

, Shadpour

. Percutaneous nephrolithotomy in patients with or without a history of open nephrolithotomy. J Endourol, 2003; 17:213–216.

28.

Lojanapiwat

. Previous open nephrolithotomy: Does it affect percutaneous nephrolithotomy techniques and outcome?. J Endourol, 2006; 20:17–20.

29.

Kurtulus

, Fazlioglu

, Tandogdu

, et al. Percutaneous nephrolithotomy: Primary patients versus patients with history of open renal surgery. J Endourol, 2008; 22:2671–2675.

30.

Traxer

, Smith

3rd , Pearle

, et al. Renal parenchymal injury after standard and mini percutaneous nephrostolithotomy. J Urol, 2001; 165:1693–1695.

31.

Dogan

, Atmaca

, Canda

, et al. Efficiency of percutaneous nephrolithotomy in pediatric patients using adult-type instruments. Urol Res, 2012; 40:259–262.

32.

Aron

, Yadav

, Goel

, et al. Percutaneous nephrolithotomy for complete staghorn calculi in preschool children. J Endourol, 2005; 19:968–972.

33.

Zeren

, Satar

, Bayazit

, et al. Percutaneous nephrolithotomy in the management of pediatric renal calculi. J Endourol, 2002; 16:75–78.

34.

Gunes

, Yahya Ugras

, Yilmaz

, et al. Percutaneous nephrolithotomy for pediatric stone disease—our experience with adult-sized equipment. Scand J Urol Nephrol, 2003; 37:477–481.

35.

Desai

. Endoscopic management of stones in children. Curr Opin Urol, 2005; 15:107–112.

36.

Jackman

, Hedican

, Peters

, Docimo

. Percutaneous nephrolithotomy in infants and preschool age children: Experience with a new technique. Urology, 1998; 52:697–701.

37.

Tugcu

, Su

, Kalfazade

. Percutaneous nephrolithotomy (PCNL) in patients with previous open stone surgery. Int Urol Nephrol, 2008; 40:881–884.

38.

Tefekli

, Ali Karadag

, Tepeler

, et al. Classification of percutaneous nephrolithotomy complications using the modified clavien grading system: Looking for a standard. Eur Urol, 2008; 53:184–190.