Urolithiasis DOI 10.1007/s00240-015-0772-6
ORIGINAL PAPER
The application of S.T.O.N.E. nephrolithometry in pediatric patients with upper urinary tract calculi treated with mini‑percutaneous nephrolithotomy Shan Doulian1 · Shayitaji Hasimu1 · Da Jun2 · Wang Lingling1 · Zhou Tuo1 · Abudukeyoumu Yusufu1 · Xu Mingxi2 · Lu Mujun2
Received: 13 January 2015 / Accepted: 8 April 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract The purpose of this study is to verify the applicability of S.T.O.N.E. nephrolithometry in pediatric patients. 103 cases of pediatric patients younger than 4 years old with upper urinary tract calculi treated with mini-percutaneous nephrolithotomy from January 2012 to March 2014 were retrospectively reviewed and evaluated using this scoring system. All procedures were performed under general anesthesia, using a 14-French nephroscope through a 16-French working access. All patients were divided into two groups according to the stages of the operations, Group A for one-stage operation and Group B for two-stage operation. 87 cases were male and 16 cases were female with the mean age of 26.5 months. The total operation time of group A was 45.89 ± 5.43 min, and 54.62 ± 5.58 min of group B (p = 0.000). The hospitalization for group A and group B was 6.63 ± 1.34 and 7.23 ± 1.24 days, respectively (p = 0.134). The total S.T.O.N.E. score was 5.93 ± 0.67 for Group A, and 7.92 ± 1.04 for Group B (p = 0.000). On further dividing each group into low/moderate/high complexity according to the total score, more cases of low/moderate complexity in group A and more cases of moderate/ high complexity in group B (χ2 = 38.096, p = 0.000) were Shan Doulian, Shayitaji Hasimu and Da Jun have contributed equally to this project. * Xu Mingxi [email protected]
reported. Our data suggest that S.T.O.N.E. nephrolithometry is applicable in pediatric upper urinary tract calculi assessment and predictive for the complexity of the operation, hospitalization, and even complications after the operation. Yet modification may be necessary to make this scoring system more distinguishable for pediatric cases. Keywords Upper urinary tract calculi · Pediatrics · Percutaneous nephrolithotomy · Nephrolithometry
Percutaneous nephrolithotomy (PCNL), as well as miniPCNL (mPCNL), is widely chosen as a first-line treatment for renal stones larger than 2 cm in pediatric patients due to its safety and efficiency [1]. To evaluate the potential risks of the procedures pre-operatively, several scoring systems have been used to evaluate the complexity of the urolithiasis. Okhunov [2] reported S.T.O.N.E. scoring system as a novel, reliable assessment for renal calculi in adult patients. It is a quantitative scoring system, using data that can be collected from noncontrast CT scans, to classify the complexity of renal calculi. This scoring system has been developed from and proved to be valuable in adult patients, but its applicability in pediatric patients has not been reported yet. In this study, we retrospectively reviewed 103 cases of PCNL performed on pediatric patients younger than 4 years old, using the S.T.O.N.E. nephrolithometry, to verify its applicability in pediatric patients.
* Lu Mujun [email protected] 1
2
Department of Urology, Second People’s Hospital of Kashi Area, Kashi 84400, Xinjiang Uygur Autonomous Region, China Department of Urology, Shanghai Ninth People’s Hospital Affiliated Shanghai JiaoTong University School of Medicine, Shanghai 200011, China
Materials and methods From January 2012 to March 2014, 103 patients who were diagnosed with upper urinary tract calculi and treated with mPCNL were included in this study, among whom 87 cases were male and 16 cases were female. The age range was
13
Urolithiasis
from 5 to 48 months, with the mean age of 26.5 months. Among these patients, 41 cases were right kidney calculi, 32 cases were left kidney calculi, 10 cases were bilateral, 10 cases were right upper ureteral stone, 6 cases were left upper ureteral stone, and 6 cases were ureteral stones with renal stones. For renal cases, 23 cases were multiple stones and 7 cases were complete staghorn stones. The stone sizes ranged from 0.7 to 2.4 cm, with mean size 1.5 cm. 6 patients presented with post-renal anuria and 3 patients presented with pyonephrosis. 65 cases of mild to moderate hydronephrosis and 38 cases without any signs of hydronephrosis were reported. Preoperatively, all patients were routinely evaluated by routine urine analysis and culture, complete blood count, coagulation tests, serum creatinine, electrocardiogram, and X-ray plain chest film. Stone-free rates were calculated according to ultrasound scan or CT scan 4 weeks after the treatment. A stone residual larger than 4 mm was considered as clinically significant residual stone, according to Chinese guidelines for renal urolithiasis [3]. All PCNL procedures were performed under general anesthesia. Patients were in lithotomy position. A 4-French ureteral catheter was placed to the operation side of ureter. Then the patients were switched to prone positions. The percutaneous access was established under ultrasound guidance. All procedures were done via one access. An 18-gauge needle went through target renal calices into the pelvis through the 11th intercostal space or below the 12th rib, between the infrascapular line and the posterior axillary line. The working tract was established with plastic amplatz dilators from 8 French to 16 French. A-14 French nephroscope was used and stone fragmentation was carried out with a pneumatic lithotripter. An ultrasound scan was performed to find stone residuals during the operation and a 10-French nephrostomy tube was placed after the procedure. For patients with renal stones on both sides, the other procedures were performed 5–7 days after the first one. S.T.O.N.E. nephrolithometry was used to evaluate the complexity of the diseases retrospectively. Two experienced urologists (assisting professors) reviewed all patients’ noncontrast CT scans and gave the scores according to the S.T.O.N.E. nephrolithometry. The 5 variables of S.T.O.N.E. are stone size (S), tract length (skin-to-stone distance, T), degree of obstruction (presence of hydronephrosis, O), number of involved calices (N), and stone essence (stone density, E). The stone size was scored from 1 to 4 according to its calculated area (0–399, 400–799, 800–1599, and ≥1600 mm2, respectively). The tract length was scored as 1 or 2 according to a mean length of ≤100 mm or >100 mm. The obstruction was evaluated according to the severity of dilation of the collecting system. No obstruction to mild
13
Table 1 Summary of S.T.O.N.E. nephrolithometry scoring system [2] Variable
Stone size (mm2) Tract length (mm) Obstruction
Score 1
2
3
4
0–399 ≤100 None
400–799 >100 Sever
800–1599
≥1600
Staghorn stone
Calices (n)
1–2
3
Essence (HU)
≤950
>950
HU Hounsfield units
dilation was assigned as 1 and moderate to severe dilation as 2. For the number of involved calices, if only one calix was involved, a score of 1 was given. If 2 or 3 calices were affected, a score of 2 was given. A maximum score of 3 was given for full staghorn calculus. The stone essence was measured on preoperative CT imaging and was scored 1 or 2 according to a radiodensity threshold of ≤950 or >950 Hounsfield units (Table 1). The total score of 3–5 was defined as low complexity, 6–8 as moderate complexity, and 9–12 as high complexity. All patients were divided into two groups according to the stages of the operations, Group A for one-stage operation and Group B for two-stage operation. Then the scores were compared between these two groups and statistical analysis was done by SPSS 11.
Results General outcomes All 103 mPCNLs were successfully performed. The mean operation time was 46.99 ± 6.16 min, ranging from 30 to 65 min. The estimated mean blood loss was 50 ml, ranging from 30 to 150 ml. No patients needed transfusion. 5 (4.85 %) cases of tract loss happened during dilation. But after second time tract establishment, satisfactory operation fields had been regained. Among all patients, 77 cases of one-stage operations and 13 cases of two-stage operations were reported. The stone-free rate (SFR) of one-stage operation was 87.4 %. 13 cases of two-stage operations were performed due to accompanying conditions like post-renal anuria, pyonephrosis, and large stone burdens which were not suitable for one-stage operations. The second operations were performed 1 month after the first operation. The SFR of two-stage operation was 84.6 %. The mean hospitalization was 6.71 ± 1.34 days, ranging from 4 to 9 days. The operation time and hospitalization of Group A and Group B are listed in Table 2, respectively.
Urolithiasis Table 2 The operation time of group A was shorter that of group B (p = 0.000)
cases of low complexity, 76 cases of moderate complexity, and 5 cases of high complexity (Table 4).
Operation time (min)
Hospitalization (days)
Group A Group B
45.89 ± 5.43 54.62 ± 5.58
6.63 ± 1.34 7.23 ± 1.24
Discussion
p
0.000
0.134
Renal stones in pediatric patients are not rare cases nowadays. The overall newly diagnosed rate of urolithiasis in pediatric population was 0.038 % in 2007 [4]. The incidence rate of urolithiasis for 0- to 5-year-old patients is about 2.8 per 100,000 person-years. And the incidence rate kept increasing 4 % per calendar year throughout a 25-year period from 1984 to 2008 [5]. The treatment of pediatric renal stone has been changed since the introduction of endoscopic surgery. There are more patients being treated, and the patients being younger, while open surgery is no longer a first option [6]. In some center, open surgery is never required in primary lithiasis cases without associated malformations [7]. PCNL is now one of the first-line treatments for renal calculi larger than 2 cm in pediatric patients. It has exceeded open surgery in hospitalization, blood transfusion rate, and D-J catheter implantation rate [8]. Several studies have shown that mini-PCNL (mPCNL), using a-14 French to 16-French working tract, is efficient enough and safe for pediatric patient diagnosed with renal stones [9]. The indications could include stones larger than 1 cm, hydronephrosis, and recurrent urinary tract infections. Age is not a contraindication, as Wang et al. [10] showed it safe to perform mPCNL on patients younger than 3 years old. Veeratterapillay even used 28-French access tract and adult instruments for the treatment of pediatric patients under 18 years old [11]. In our cases, all mPCNLs were successfully performed on pediatric patients. Similar to previous studies, mPCNL showed acceptable efficiency in stone clearance and low complication rate in patients younger than 4 years old. The stone-free rate for one-stage operation and two-stage operation was 87.4 and 84.6 %, respectively. Of all cases, the incidence rate of grade II complications was 17.5 %, and for grade IIIb was 2.9 %, according to the modified Clavien system [12]. All patients presented with any complications were cured after either administration of antibiotics
There was no difference regarding the hospital stay of both groups (p = 0.134)
Complications and follow‑up 18 cases (17.48 %) with fever (>38.5 °C) were observed in our study. After administration of antibiotics according to pre-operative urine culture results, all patients were fully recovered and discharged with normal body temperature and urine test results. 3 (2.91 %) cases of renal pelvis perforation were noticed during operation. These patients were treated with retroperitoneal drainage and discharged with no further complications. One case (0.97 %) of late-onset hematuria was treated by strict bed rest and got full recovery. There was no injury of colon, urosepsis, sever bleeding, or nephrectomy in our study. The mean follow-up time was 26 months, ranging from 18 to 36 months. The recurrence of the stone was found in 8 patients (8.6 %). Ultrasound scanning during follow-up showed no atrophy of kidneys, and 12 cases (12.9 %) of mild hydronephrosis and ureterectasia. Detailed distribution is listed in Table 3. S.T.O.N.E. scores The total score of all cases was 6.18 ± 0.98, ranged from 5–9. The stone size score was 1.07 ± 0.25, the tract length score 1.00 ± 0.00, the obstruction score 1.63 ± 0.48, the calices score 1.16 ± 0.39, and the essence score 1.33 ± 0.47. The total score was 5.93 ± 0.67 for Group A, and 7.92 ± 1.04 for Group B (p = 0.000). Then each group was subset according to the stone complexity. According to the definition of the scoring system, a total score of 3–5 stands for low complexity, 6–8 for moderate complexity, and 9–12 for high complexity. In our study, there are 22
Table 3 More complications were recorded in group B during the perioperative period (p
ORIGINAL PAPER
The application of S.T.O.N.E. nephrolithometry in pediatric patients with upper urinary tract calculi treated with mini‑percutaneous nephrolithotomy Shan Doulian1 · Shayitaji Hasimu1 · Da Jun2 · Wang Lingling1 · Zhou Tuo1 · Abudukeyoumu Yusufu1 · Xu Mingxi2 · Lu Mujun2
Received: 13 January 2015 / Accepted: 8 April 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract The purpose of this study is to verify the applicability of S.T.O.N.E. nephrolithometry in pediatric patients. 103 cases of pediatric patients younger than 4 years old with upper urinary tract calculi treated with mini-percutaneous nephrolithotomy from January 2012 to March 2014 were retrospectively reviewed and evaluated using this scoring system. All procedures were performed under general anesthesia, using a 14-French nephroscope through a 16-French working access. All patients were divided into two groups according to the stages of the operations, Group A for one-stage operation and Group B for two-stage operation. 87 cases were male and 16 cases were female with the mean age of 26.5 months. The total operation time of group A was 45.89 ± 5.43 min, and 54.62 ± 5.58 min of group B (p = 0.000). The hospitalization for group A and group B was 6.63 ± 1.34 and 7.23 ± 1.24 days, respectively (p = 0.134). The total S.T.O.N.E. score was 5.93 ± 0.67 for Group A, and 7.92 ± 1.04 for Group B (p = 0.000). On further dividing each group into low/moderate/high complexity according to the total score, more cases of low/moderate complexity in group A and more cases of moderate/ high complexity in group B (χ2 = 38.096, p = 0.000) were Shan Doulian, Shayitaji Hasimu and Da Jun have contributed equally to this project. * Xu Mingxi [email protected]
reported. Our data suggest that S.T.O.N.E. nephrolithometry is applicable in pediatric upper urinary tract calculi assessment and predictive for the complexity of the operation, hospitalization, and even complications after the operation. Yet modification may be necessary to make this scoring system more distinguishable for pediatric cases. Keywords Upper urinary tract calculi · Pediatrics · Percutaneous nephrolithotomy · Nephrolithometry
Percutaneous nephrolithotomy (PCNL), as well as miniPCNL (mPCNL), is widely chosen as a first-line treatment for renal stones larger than 2 cm in pediatric patients due to its safety and efficiency [1]. To evaluate the potential risks of the procedures pre-operatively, several scoring systems have been used to evaluate the complexity of the urolithiasis. Okhunov [2] reported S.T.O.N.E. scoring system as a novel, reliable assessment for renal calculi in adult patients. It is a quantitative scoring system, using data that can be collected from noncontrast CT scans, to classify the complexity of renal calculi. This scoring system has been developed from and proved to be valuable in adult patients, but its applicability in pediatric patients has not been reported yet. In this study, we retrospectively reviewed 103 cases of PCNL performed on pediatric patients younger than 4 years old, using the S.T.O.N.E. nephrolithometry, to verify its applicability in pediatric patients.
* Lu Mujun [email protected] 1
2
Department of Urology, Second People’s Hospital of Kashi Area, Kashi 84400, Xinjiang Uygur Autonomous Region, China Department of Urology, Shanghai Ninth People’s Hospital Affiliated Shanghai JiaoTong University School of Medicine, Shanghai 200011, China
Materials and methods From January 2012 to March 2014, 103 patients who were diagnosed with upper urinary tract calculi and treated with mPCNL were included in this study, among whom 87 cases were male and 16 cases were female. The age range was
13
Urolithiasis
from 5 to 48 months, with the mean age of 26.5 months. Among these patients, 41 cases were right kidney calculi, 32 cases were left kidney calculi, 10 cases were bilateral, 10 cases were right upper ureteral stone, 6 cases were left upper ureteral stone, and 6 cases were ureteral stones with renal stones. For renal cases, 23 cases were multiple stones and 7 cases were complete staghorn stones. The stone sizes ranged from 0.7 to 2.4 cm, with mean size 1.5 cm. 6 patients presented with post-renal anuria and 3 patients presented with pyonephrosis. 65 cases of mild to moderate hydronephrosis and 38 cases without any signs of hydronephrosis were reported. Preoperatively, all patients were routinely evaluated by routine urine analysis and culture, complete blood count, coagulation tests, serum creatinine, electrocardiogram, and X-ray plain chest film. Stone-free rates were calculated according to ultrasound scan or CT scan 4 weeks after the treatment. A stone residual larger than 4 mm was considered as clinically significant residual stone, according to Chinese guidelines for renal urolithiasis [3]. All PCNL procedures were performed under general anesthesia. Patients were in lithotomy position. A 4-French ureteral catheter was placed to the operation side of ureter. Then the patients were switched to prone positions. The percutaneous access was established under ultrasound guidance. All procedures were done via one access. An 18-gauge needle went through target renal calices into the pelvis through the 11th intercostal space or below the 12th rib, between the infrascapular line and the posterior axillary line. The working tract was established with plastic amplatz dilators from 8 French to 16 French. A-14 French nephroscope was used and stone fragmentation was carried out with a pneumatic lithotripter. An ultrasound scan was performed to find stone residuals during the operation and a 10-French nephrostomy tube was placed after the procedure. For patients with renal stones on both sides, the other procedures were performed 5–7 days after the first one. S.T.O.N.E. nephrolithometry was used to evaluate the complexity of the diseases retrospectively. Two experienced urologists (assisting professors) reviewed all patients’ noncontrast CT scans and gave the scores according to the S.T.O.N.E. nephrolithometry. The 5 variables of S.T.O.N.E. are stone size (S), tract length (skin-to-stone distance, T), degree of obstruction (presence of hydronephrosis, O), number of involved calices (N), and stone essence (stone density, E). The stone size was scored from 1 to 4 according to its calculated area (0–399, 400–799, 800–1599, and ≥1600 mm2, respectively). The tract length was scored as 1 or 2 according to a mean length of ≤100 mm or >100 mm. The obstruction was evaluated according to the severity of dilation of the collecting system. No obstruction to mild
13
Table 1 Summary of S.T.O.N.E. nephrolithometry scoring system [2] Variable
Stone size (mm2) Tract length (mm) Obstruction
Score 1
2
3
4
0–399 ≤100 None
400–799 >100 Sever
800–1599
≥1600
Staghorn stone
Calices (n)
1–2
3
Essence (HU)
≤950
>950
HU Hounsfield units
dilation was assigned as 1 and moderate to severe dilation as 2. For the number of involved calices, if only one calix was involved, a score of 1 was given. If 2 or 3 calices were affected, a score of 2 was given. A maximum score of 3 was given for full staghorn calculus. The stone essence was measured on preoperative CT imaging and was scored 1 or 2 according to a radiodensity threshold of ≤950 or >950 Hounsfield units (Table 1). The total score of 3–5 was defined as low complexity, 6–8 as moderate complexity, and 9–12 as high complexity. All patients were divided into two groups according to the stages of the operations, Group A for one-stage operation and Group B for two-stage operation. Then the scores were compared between these two groups and statistical analysis was done by SPSS 11.
Results General outcomes All 103 mPCNLs were successfully performed. The mean operation time was 46.99 ± 6.16 min, ranging from 30 to 65 min. The estimated mean blood loss was 50 ml, ranging from 30 to 150 ml. No patients needed transfusion. 5 (4.85 %) cases of tract loss happened during dilation. But after second time tract establishment, satisfactory operation fields had been regained. Among all patients, 77 cases of one-stage operations and 13 cases of two-stage operations were reported. The stone-free rate (SFR) of one-stage operation was 87.4 %. 13 cases of two-stage operations were performed due to accompanying conditions like post-renal anuria, pyonephrosis, and large stone burdens which were not suitable for one-stage operations. The second operations were performed 1 month after the first operation. The SFR of two-stage operation was 84.6 %. The mean hospitalization was 6.71 ± 1.34 days, ranging from 4 to 9 days. The operation time and hospitalization of Group A and Group B are listed in Table 2, respectively.
Urolithiasis Table 2 The operation time of group A was shorter that of group B (p = 0.000)
cases of low complexity, 76 cases of moderate complexity, and 5 cases of high complexity (Table 4).
Operation time (min)
Hospitalization (days)
Group A Group B
45.89 ± 5.43 54.62 ± 5.58
6.63 ± 1.34 7.23 ± 1.24
Discussion
p
0.000
0.134
Renal stones in pediatric patients are not rare cases nowadays. The overall newly diagnosed rate of urolithiasis in pediatric population was 0.038 % in 2007 [4]. The incidence rate of urolithiasis for 0- to 5-year-old patients is about 2.8 per 100,000 person-years. And the incidence rate kept increasing 4 % per calendar year throughout a 25-year period from 1984 to 2008 [5]. The treatment of pediatric renal stone has been changed since the introduction of endoscopic surgery. There are more patients being treated, and the patients being younger, while open surgery is no longer a first option [6]. In some center, open surgery is never required in primary lithiasis cases without associated malformations [7]. PCNL is now one of the first-line treatments for renal calculi larger than 2 cm in pediatric patients. It has exceeded open surgery in hospitalization, blood transfusion rate, and D-J catheter implantation rate [8]. Several studies have shown that mini-PCNL (mPCNL), using a-14 French to 16-French working tract, is efficient enough and safe for pediatric patient diagnosed with renal stones [9]. The indications could include stones larger than 1 cm, hydronephrosis, and recurrent urinary tract infections. Age is not a contraindication, as Wang et al. [10] showed it safe to perform mPCNL on patients younger than 3 years old. Veeratterapillay even used 28-French access tract and adult instruments for the treatment of pediatric patients under 18 years old [11]. In our cases, all mPCNLs were successfully performed on pediatric patients. Similar to previous studies, mPCNL showed acceptable efficiency in stone clearance and low complication rate in patients younger than 4 years old. The stone-free rate for one-stage operation and two-stage operation was 87.4 and 84.6 %, respectively. Of all cases, the incidence rate of grade II complications was 17.5 %, and for grade IIIb was 2.9 %, according to the modified Clavien system [12]. All patients presented with any complications were cured after either administration of antibiotics
There was no difference regarding the hospital stay of both groups (p = 0.134)
Complications and follow‑up 18 cases (17.48 %) with fever (>38.5 °C) were observed in our study. After administration of antibiotics according to pre-operative urine culture results, all patients were fully recovered and discharged with normal body temperature and urine test results. 3 (2.91 %) cases of renal pelvis perforation were noticed during operation. These patients were treated with retroperitoneal drainage and discharged with no further complications. One case (0.97 %) of late-onset hematuria was treated by strict bed rest and got full recovery. There was no injury of colon, urosepsis, sever bleeding, or nephrectomy in our study. The mean follow-up time was 26 months, ranging from 18 to 36 months. The recurrence of the stone was found in 8 patients (8.6 %). Ultrasound scanning during follow-up showed no atrophy of kidneys, and 12 cases (12.9 %) of mild hydronephrosis and ureterectasia. Detailed distribution is listed in Table 3. S.T.O.N.E. scores The total score of all cases was 6.18 ± 0.98, ranged from 5–9. The stone size score was 1.07 ± 0.25, the tract length score 1.00 ± 0.00, the obstruction score 1.63 ± 0.48, the calices score 1.16 ± 0.39, and the essence score 1.33 ± 0.47. The total score was 5.93 ± 0.67 for Group A, and 7.92 ± 1.04 for Group B (p = 0.000). Then each group was subset according to the stone complexity. According to the definition of the scoring system, a total score of 3–5 stands for low complexity, 6–8 for moderate complexity, and 9–12 for high complexity. In our study, there are 22
Table 3 More complications were recorded in group B during the perioperative period (p
