The effectiveness of extracorporeal shock wave lithotripsy for lower calyx stones in children

Introduction

The incidence rate of urinary stone disease (USD) varies from 1 to 20% in adults and from 1 to 5% in children [1][2][3]. Recent epidemiological studies showed an increase in the incidence rate of USD in children from Western counties, especially, in the representatives of the Caucasian race and older children [4][5][6]. The choice of the method of surgical treatment for stones in children is made considering numerous factors: size, localization, and density of the stone, the patient’s age, and anatomic-physiological peculiarities of the child’s organism. The treatment of urolithiasis of the lower calyx in children is considered to be the most complicated task because the outcome of stone fragments is complicated by the influence of gravitation that prevents the elimination after stone disintegration. According to the recommendations of EAU, extracorporeal shock wave lithotripsy (ESWL) is indicated as the first option of treatment for stones smaller than 10 mm in the lower calyx. Percutaneous nephrolithotripsy (PNL) is indicated for patients with stones larger than 10 mm. Relevant recommendations are based on the published data that demonstrate the low efficiency of ESWL of the lower calyx after the first session. Demirkesen et al. registered a complete elimination of stones in 42% of patients after the first ESWL session and in 62% of patients after the repeated sessions [7]. Obek et al. observed stone-free status in 36% of patients after the first ESWL session and in 66% of patients after the repeated sessions [8]. According to Özgür et al. [9], the rate of the complete elimination of lower calyx stones in children after the repeated sessions of ESWL was only 55.9%.

The study aimed to evaluate the effectiveness of ESWL in the treatment of lower calyx stones smaller and larger than 10 mm.

Materials and Methods

ESWL was performed on 194 patients for 229 stones in 2013–2018. In 33 patients (17%), stones were localized in the lower calyx. Patients were divided into 2 groups. Group I included 24 patients (72.7%) with primary stones in the lower calyx. Group II included 9 patients (27.3%) with residual lower calyx stones that migrated after the previous ESWL session (Table 1). Each group was divided into subgroups by the size of the stones. Subgroup Ia included 16 patients (66.67%) with stones < 1 cm; Subgroup Ib – 8 patients (33.33%) with stones ˃1 cm; Subgroup IIa – 6 patients (66.7%) with stones ˂1 cm; Subgroup IIb – 3 patients (33.3%) with stones ˃ 1 cm.

ESWL has performed using Dornier Compact Sigma lithotripter under general anaesthesia and ultrasonic control. In patients with residual stones > 5 mm after ESWL, ESWL sessions were repeated not earlier than 5 days after the first session.

The method of inversion was used in the postoperative period. Under parental control, the children were held for 3–5 minutes upside down 3–4 times a day for percussion in the projection of kidneys. Ultrasonic control investigation was performed daily for 3 days after an ESWL session. Lithokinetic therapy was performed (renal water load combined with the administration of diuretic and antispasmodic drugs) in the postoperative period. The treatment was performed without preliminary drainage of the upper urinary tract. The result was considered positive when a complete elimination of stones was achieved.

Statistical analysis. Statistical processing of the obtained data were made with the software STATISTICA 10 (StatSoft Inc., Tulsa, USA). Descriptive statistics for countable parameters included mean values and standard deviation. The associations between quantitative parameters were studied with the non-parametric Mann-Whitney test and qualitative parameters with precise Fisher’s test. The difference was statistically significant at 0.05.

Results

The differences were revealed in the age of patients from Subgroups Ia and Ib. The age of patients from Subgroup Ib was younger than in patients with primary stones smaller than 1 cm (p = 0.012) (Table 2).

After ESWL, in 21 out of 24 patients (87.5%) from Group I, complete elimination of stones was observed. In Group II, complete elimination of stones was observed in all 9 patients (100%).

After the first ESWL session, stone-free status was observed in 63.6% of patients in two groups; after the second ESWL session, in 78.8% of patients; after the third ESWL session, in 90.9% of patients. In patients from Subgroups Ia – IIa, after the first ESWL session, complete elimination of stones was registered in 63.6% of cases, and after further sessions, the rate of successful outcome was observed in 90.9%. After the first ESWL session in children from Subgroups Ib-IIb, complete elimination of stones was achieved in 63.6% of patients. After the repeated sessions, the rate of successful outcomes was observed in 90.9% (Table 2). In patients from Subgroup Ia after the first ESWL session, the rate of stone-free status was higher (78.6%) than in patients from Subgroup IIa (50%) (p > 0.05).

The comparison of the rate of the complete elimination of lower calyx stones after ESWL in patients from Groups I and II did not reveal any significant differences after the first session (up to 66.6% vs in Group I versus 55.5% in Group II (p > 0.05)) and after the repeated sessions (up to 87.5% in Group I versus 100% (p > 0.05)).

The mean number of ESWL sessions per one stone in Group I was 1.4, and in Group II – 1.5. The total number of ESWL sessions was 48. The mean number of sessions per one stone was 1.4 among all the patients with lower calyx stones.

The fragmentation of concrements failed in one patient from Group I after two ESWL sessions. There were no cases of UTI, renal colic, and steinstrasse observed in the postoperative period.

Discussion

ESWL is widely used for the fragmentation of stones in children. The most important factors that determine the potential effectiveness of ESWL for the complete elimination of stones are the localization and size of stones. When stones are localized in the calyx and ureter’s upper third, the rate of the complete elimination of stones is 90%. When the stones are localized in the lower calyxes, the efficiency of ESWL is much lower.

Obek et al. [8] noted that ESWL was quite efficient in the fragmentation of stones localized in any calyxes. After the first ESWL session, a complete elimination was observed in 36%, 46%, and 41% of cases (p = 0.4) when stones were localized in the lower, middle, and upper groups of calyxes, respectively. The authors revealed a significant correlation between the rate of a complete elimination and the number of repeated ESWL sessions, as well as the number of stones. The total rate of the complete elimination of stones was 66% (63%, 73%, and 71% (p = 0.1)) in patients with stones of the lower, middle, and upper calyxes, respectively. In patients with stones larger than 2 cm, the rate of stone-free status was observed in 49% (53%, 60%, and 23% in the lower, middle, and upper calyxes, respectively). The authors recommend ESWL as a method of treatment for calyx stones smaller than 2.0 cm in all groups of calyxes. The treatment for patients with stones larger than 2.0 cm should be individual and requires further studies.

Demirkesen et al. [7] evaluated and compared the effectiveness of ESWL for stones of various sizes in the lower, middle, and upper calyxes in children. In children with stones smaller than 2 cm, stone-free status was achieved in 42% of patients with stones in the lower calyx, in 46.1% – in the middle calyx, and 49.3% – in the upper calyx, respectively. After the repeated ESWL sessions, the effectiveness was higher and reached 62% and 65.3% in the middle and upper groups of calyxes. In groups with stones larger than 2 cm, a complete elimination was achieved in 33% of patients in all groups of calyxes. The authors believe that ESWL is effective and can be indicated as the treatment of choice for stones in all groups of calyxes smaller than 2 cm.

Goktas et al. [10] analyzed the results of fragmentation and elimination of stones < 2.5 cm in the lower calyx in children and adults after the first ESWL session. Complete elimination of stones was observed in 66.6% of children and 28% of adults (p = 0.0001). The control examination 3 months after the treatment showed that stone-free status was achieved in 85% of children and 31.5% of adults (p = 0.0001). The probability of additional ESWL sessions is higher in adults (20.2%) than in children (3.7%). The authors believe that ESWL is a preferable option of treatment for lower calyx stones in children, which is more effective than in adults.

El-Nahas et al. [11] analyzed the experience of ESWL application and noted that complete elimination of stones after ESWL in children depended on the size and localization of stones. The authors recommend ESWL for children with middle and upper calyx stones <15mm and lower calyx stones <11 mm. A complete elimination was observed in 71% of cases.

Kumar et al. [12] believe that the application of ESWL in the treatment for lower calyx stones 1–2 cm is associated with a higher rate of repeated sessions in comparison with transcutaneous nephrolithotripsy (41.5% versus 2.8%). However, the application of contact lithotripsy is associated with a higher rate of complications (20.7% versus 3.7%; p = 0.01), longer time of operation, and hospitalization.

ElSheemy et al. [13] compared the results of PNL and ESWL in children with lower calyx and pelvic stones 10–25 mm. The rate of the complete elimination of the lower calyx stones after the first PNL session was 93.3%. After the first ESWL session, it was 16.7% (p < 0.001), and after the repeated sessions – 66.7% (p = 0.139). The authors noted a higher rate of complete stone elimination after mini-percutaneous nephrolithotripsy (MPNL) than after ESWL in patients with lower calyx stones. MPNL is associated with a lower rate of repeated interventions.

A low rate of the complete elimination of lower calyx stones after ESWL can be associated with the anatomy of the lower calyx, and the residual fragments can become a matrix for the stone growth. However, the studies conducted by Onal et al. [14] showed that the anatomy of calyxes and pelvis in children with lower calyx stones did not affect significantly the elimination of fragments after ESWL. The probability of repeated ESWL sessions in patients with multiple stones should be considered when choosing the methods of treatment.

Danuser et al. [15] did not reveal the influence of anatomic peculiarities of the calyx system on the elimination of stones either. The authors reported stone-free status in 68% of cases in lower calyxes 3 months after ESWL and concluded that ESWL was a possible treatment option for lower calyx stones.

Apart from the generally accepted lithokinetic therapy after ESWL session, which includes the indication of spasmolytic and diuretic drugs, patients are recommended to stay in the vertical position, as well as jump and drink a lot. This contributes to the elimination of stone fragments.

After ESWL of the lower calyx stone, the method of inversion was frequently applied by the authors. The authors offered parents to change the position of their child. Under parental control, a child was turned upside down for 30–60 seconds and the specialists performed light percussion in the projection of kidneys. Besides, tumbling, puzzle collection, and movement of hands along on the floor from the lying position on the bed were recommended for a child. In this position, lower calyxes become higher than the renal pelvis, which contributes to the movement of fragments into it. Such manipulations are performed repeatedly when children are awake and perceived as a game. Unfortunately, this technique is not always applicable to adults.

Another frequently used method is proposed by Faure et al. [16] (2016). The authors noted the safety and effectiveness of inversion and mechanical percussion and diuresis (MPD) for the elimination of stones in children after ESWL. Thirty minutes before the therapy, children were offered to drink 10 ml of water per 1 kg of their body weight. Then, children lied on the bed at a 45° angle and received continuous 10-minute percussion from a physiotherapist. The general rate of stone elimination in the study was 65%. This therapy is a valuable addition to the method of treatment and elimination of stone.

Peng et al. [17] believe that physiotherapy did not become widespread in clinical practice because of the lack of high-level evidence and standard protocol. The performed meta-analysis showed that physiotherapy was effective for the elimination of stones after ESWL and retrograde intrarenal surgery (RIRS), especially for the elimination of lower calyx, pelvic, and upper third ureter stones, and did not lead to the development of side effects.

Thus, according to the available published data, the rate of achievement of stone-free status after the first ESWL session varied within 16.7–42% and after the last session – from 62–68% versus higher levels obtained by the authors after the analysis of their data (63.6 and 90.9%, respectively).

Conclusion

ESWL demonstrates high effectiveness in the therapy for lower calyx stones in children after the first and repeated sessions (second and third). The authors did not reveal any significant differences in the effectiveness depending on the stone sizes. The rate of the complete elimination of stones did not differ significantly during the treatment of primary and residual migrated stones.