*Department of Urology, Primaya Hospital PGI Cikini, Jakarta, Indonesia. **Faculty of Medicine and Health Science, Atma Jaya Catholic University of Indonesia, Jakarta, Indonesia.
ABSTRACT
INTRODUCTION
The incidence of urolithiasis in children within the past twenty years continues to increase steadily every year with a ratio of 4-10% per year.1 In children it will be difficult to determine the pain experienced, but the symptoms typically in the form of crying, anxiety, vomiting, hematuria, traces of blood or small stones on diapers, or recurrent urinary tract infections (UTI) with painful micturition.2 20% of kidney stones are found in the
ureters which cause discomfort and can result in kidney damage.3 The modality of treatment that can be given is influenced by the location and size of the stone, degree of back-pressure, as well as associated UTI.4 The treatment is in the form of observation, medical expulsive therapy (MET), ureteroscopy (URS), and ureterolithotomy.3 The AUA and the Endourological Society recommend URS and ESWL for patients who have failed MET and may require surgical intervention. URS has been evaluated
Corresponding author: Nicholas Andrian Singgih E-mail: nicholasandrian1606@gmail.com
Received 30 June 2023 Revised 24 July 2023 Accepted 25 July 2023 ORCID ID:http://orcid.org/0000-0002-7331-3070 https://doi.org/10.33192/smj.v75i9.263934
All material is licensed under terms of the Creative Commons Attribution 4.0 International (CC-BY-NC-ND 4.0) license unless otherwise stated.
Singgih et al.
as safe for both adults and children, although there is a risk of failure in the initial attempt.1 However, failure rates are higher in children than in adults due to the smaller width of the ureter, making URS challenging in children.1,3
There is controversy regarding the risk of routine prestenting and dilation of balloons to gain ureteral access in children because of the risk of ureteral perforation and ureteral stricture. Ureteral access is often obstructed at the ureteral orifice or intramural ureter, where there are many α1-adrenergic receptors. The presence of alpha blockers can reduce muscle contractions around the ureteral orifice.5 In addition, it can reduce basal tonicity, reduce peristaltic activity and intraluminal tone.3 To our knowledge, there is not much literature about the use of tamsulosin for ureteroscopy in pediatrics. Thus, we conduct a systematic review and meta-analysis to find out the effectiveness of tamsulosin for ureteroscopy access in pediatrics.
MATERIALS AND METHODS
We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines 2020.6 Our search encompassed relevant literature from PubMed, Proquest, EBSCO, and the Cochrane Library databases. We utilized specific search terms such as “alpha blocker”, “alpha adrenergic blocker”, “tamsulosin”, “silodosin”, and “α-blocker” in conjunction with terms like “ureteroscopy”, “ureteroscopic”, and “retrograde intrarenal surgery”. Furthermore, we included terms related to the target population, such as “children”, “adolescence”, “pediatric”, and “school-age children”. To ensure comprehensiveness, we manually examined the reference lists of selected manuscripts for potential articles that met our inclusion criteria.
This systematic review incorporated a variety of study designs, including Randomized Control Trials (RCTs), case-control studies, retrospective cohorts, and prospective cohorts. To be included in this review, studies needed to fulfil specific criteria. Firstly, studies had to compare the use of perioperative alpha blockers with no alpha blockers in the context of ureteroscopy (URS) access. This comparison aimed to examine the potential effects of alpha blockers on the outcomes of interest. Secondly, the study population had to consist of patients who were under the age of 18. Lastly, the reported outcomes of interest included URS success in
the initial attempt and surgical time. Those outcomes were chosen to assess the efficacy and efficiency of utilizing perioperative alpha blockers during URS procedures. To maintain the rigor of our review, we excluded certain types of articles that did not meet our criteria, including case reports, reviews, and conference abstracts, as they were not deemed suitable for inclusion in our analysis.
The data extraction process was carried out independently by 3 reviewers. The data extracted included first author, year of publication, country where the study was conducted, study design, sample sizes, age, sex, body mass index (BMI), stone size, duration of alpha blocker administration, surgical time, and success rate. The primary outcome was the success rate in the initial URS attempt. Secondary outcome was the length of surgical time. Disagreements or discrepancies were discussed by all authors.
Six reviewers contributed to assessing the quality of bias, with each study independently evaluated by two reviewers using the Newcastle-Ottawa Scale (NOS) for cohort and case-control studies. The NOS is a commonly used tool to assess the quality of non-randomized studies. The maximum score on the NOS is 9. Studies that received a score of 7-9 stars were considered to have a low risk of bias, studies scoring 4-6 stars were considered to have moderate risk, while studies scoring 3 or less stars were considered to have a high risk of bias.7 This rigorous assessment process ensured a comprehensive evaluation of the included studies and provided valuable insights into their methodological quality and potential sources of bias.
For the analysis of primary outcomes with dichotomous data, we utilized an OR along with a 95% CI. A p-value below 0.05 was considered statistically significant. This approach allowed us to assess the association between the use of preoperative alpha blockers and the outcomes of interest in a binary manner. On the other hand, secondary outcomes, which involved continuous variables, were analyzed using weighted mean differences (WMD). This method enabled us to compare the differences in means between groups and quantify the effect sizes for these variables. To assess heterogeneity between studies, we calculated the I2 index. If the I2 value exceeded 50%, indicating substantial heterogeneity, we applied the random effects model for the meta-analysis. Conversely, if
the I2 value was below 50%, indicating low heterogeneity, we employed the random-effect model. These models help account for differences across studies and provide a pooled estimate of the effect size. For the statistical analysis, we used RevMan 5.4. software on a Macbook platform. This widely used software facilitated the analysis and synthesis of the data, allowing us to generate forest plots and descriptive narratives to present the outcomes visually and concisely.
RESULTS
The comprehensive flow diagram of study selection with subsequent exclusions is presented in Fig 1. A total of 120 studies were found using the search term in four databases. From the first screening, we excluded 42 articles because they did not meet our inclusion criteria from the screening of the title and the abstract. We included
3 suitable English publications in the meta-analysis after removing duplicates and examining the titles, abstracts, and full texts. Of these studies, two were published from the USA and one from Pakistan.
The baseline characteristics of the included studies are presented in Table 1. This study consisted of three articles, including two cohort studies and one case- control study, with a total of 235 participants.1,3,5 The average age in each group ranged from 11.7 to 13.7 years old. The intervention groups received alpha blockers (specifically, tamsulosin), while the control groups did not receive alpha blockers. The duration of alpha blocker administration before the ureteroscopy procedure ranged from 2 to 7 days. All studies utilized tamsulosin as the alpha blocker intervention. The average body mass index
TABLE 1. Characteristics of included studies.
Author, year | Country | Study design | Group | Protocol | Duration of administration | Uretroscope | Age (year) | Body mass index (BMI) | Stone size (mm) | Length of surgery | Outcome | Success rate (%) | Stone free |
(min (SD)) | rate (%) | ||||||||||||
McGee LM, et al., 2021.1 | USA | Retrospec tive | Intervention | Tamsulosin 0.4 mg | >=7 days | Olympus P6 Flexible URS | 13.0 | 23.3 | 6.5 | 40.5 (26.2) | Success rate, stone | 62% | 75% |
free rate | |||||||||||||
Control | No | 13.7 | 23.2 | 6. 3 | 36.1 (16.0) | Success | 39% | 50% | |||||
tamsulosin | rate, stone | ||||||||||||
free rate | |||||||||||||
Morley C, et al., 2020.5 | USA | Retrospec tive | Intervention | Tamsulosin 0.4 mg | 2 days | Semi rigid (wolf 4.5 Fr), | 12.2 | 23.8 | 2 | NA | Success rate | 88% | NA |
Control | No | flexible URS | 11.7 | 21.2 | 3.25 | NA | Success | 65.40% | NA | ||||
tamsulosin | (Storz 7.5 Fr) | rate | |||||||||||
Khan A, | Pakistan | Case | Intervention | Tamsulosin | 7 days | NA | 12.9 | 24.1 | 6.59 | 43.91 | Success | 72.73% | NA |
et al., 2022.3 | control | 0.4 mg | (20.11) | rate | |||||||||
Control | No | 12.9 | 25.2 | 7.44 | 40.70 | Success | 52.73% | NA | |||||
tamsulosin | (22.37) | rate |
(BMI) ranged between 21.2 and 25.2. The average stone size, as reported in the studies, ranged between 2 and 7.44
mm. Based on the length of surgery, the administration of alpha blockers took longer compared to the absence of alpha blockers. The success rate of the three studies indicated that the administration of alpha blockers led to an increased success rate of ureteroscopy access in pediatric patients. There were significant differences of patients’ age, stone and URS size between the two cohort studies.1,5
Quality assessment was conducted to evaluate the risk of bias using the Newcastle-Ottawa Scale (NOS). The results revealed that the two retrospective studies included in this study obtained a mean total score of 7, while the case-control study obtained a mean total score of 7 as well. These scores indicate that the included studies were considered to be of good quality. The NOS is a widely recognized tool for assessing the quality of non-randomized studies, and its application in this study provides confidence in the reliability and validity of the findings. The high scores obtained by the included studies suggest that they had a low risk of bias and were methodologically robust.7 The NOS assessment is presented in Table 2.
There was a significant difference in the success rate of ureteroscopy access between the alpha blockers group and the control group, with an odds ratio (OR) of 2.73 (1.52-4.91; 95% confidence interval; p=0.0008). Heterogeneity analysis among the studies yielded an I2 index of 0%. Therefore, a random-effects model was applied based on the collected study heterogeneity. The analysis of the success rate of ureteroscopy access was presented as a forest plot in Fig 2. This funnel plot
showed that it is symmetrical, indicating a low risk of bias (Fig 3).
Among the 3 studies included, only 2 studies were measuring the length of surgery. Between the control group and the alpha blocker group, there was no significant difference in surgical time during the ureteroscopy surgery, with a mean difference of 3.46 (-3.59-10.50; 95% confidence interval; p=0.34). The heterogeneity analysis among the studies was low (P=0.79, I2=0%), and a random effect model was used for data synthesis. The analysis of length surgery was presented as a forest plot in Fig 3. This funnel plot showed that it is symmetrical, indicating a low risk of bias (Fig 5).
DISCUSSION
Urolithiasis is a common case, even in children. Recently, several studies have reported an increase in the incidence of pediatric urolithiasis.1,4,5 McGee LM, et al. described the incidence in the last 20 years has been estimated at 4-10%. The increasing incidence of urolithiasis in children has strengthened the evaluation of kidney stone management.1 Pediatrics need a precise identification of the underlying cause and personalized treatments to prevent recurrences of stone formation. It is crucial to see the medical history, find out urinary and dietary habits, perform some tests such as urine and blood tests, as well as analyze urinary stone composition.8 Disease recurrence can be prevented by dietary adjustment and pharmaceutical intervention. Acute management of the condition comprises monitoring with supportive care, medical expulsive therapy (MET), and surgical intervention.9 In the past, treatment for urinary tract stone diseases was performed by open surgeries, but recently there has been a significant drive toward minimally invasive surgery (MIS), such as extracorporeal shockwave lithotripsy (ESWL), ureteroscopy (URS), retrograde intrarenal surgery (RIRS),
TABLE 2. Newcastle Ottawa Scale for cohort.
Selection | Comparability | Outcome | Total score | |||||||
No | Author, | Representative | Selection of | Ascertainment | Demonstrain | Comparability | Assessment | Was follow up | Adequacy | |
year | of the exposed | the non-exposed | of exposure | that outcome | of cohort on | of outcome | long enough | of follow up | ||
cohort | cohort | of interest was not present at start of study | the basis of the design or analysis | for outcome to occur | cohort | |||||
1 | Morley, et al. (2020) | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 7 |
2 | McGee et al. (2021) | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 7 |
TABLE 3. Newcastle Ottawa Scale for case control.
Selection | Comparability | Outcome | Total score | ||||||
No Author, | Is the case | Representativeness | Selection | Definition | Comparability | Ascertainment | Same | Non- | |
year | definition adequate | of the cases | of Controls | of Controls | of cases and controls on the basis of the design or analysis | of exposure | method of ascertainment for cases and controls | Response rate | |
1 Khan et al. (2022) | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 7 |
= Mean Difference
and percutaneous nephrolithotomy (PCNL). According to the European Association of Urology (EAU) guidelines for the management of urinary stone disease in children, robotic-assisted laparoscopic surgery approaches are good alternatives in patients with a history of previous failed endoscopic procedures, complex renal anatomy (ectopic or retrorenal colon), concomitant ureteropelvic junction obstruction (UPJO) or calyceal diverticula, mega-ureter, or large impacted stones. Miniaturized
instruments and new technological developments have led to many innovations in the surgical management of pediatric urolithiasis.8
The use of ureteroscopy for stone management in children can be a good option. Straub, et al. mentioned that the URS procedure is the most ideal procedure for stones in the mid and distal ureters.9 In a study conducted by Whatley A, et al., with an average age of 8.5 years showed that the use of ureteroscopy in the
treatment of urolithiasis resulted in an 87% stone-free rate with an average operating time of 62 minutes.11 Another research according to Nerli, et al. found that the use of ureteroscopy as therapy in children under 60 months of age proved effective and safe in ureteral and renal pelvic stones. However, in this study, before the ureteroscopy procedure, dilatation of the ureter was required first.12 It is challenging and risky to advance a ureteroscope into the non-dilated ureter; failure to do might result in the procedure’s failure.13 A systematic review by Rob S, et al. showed equally high SFRs and safety profiles of URS in pediatrics may be attained by medium-volume centers as well as large-volume centers, hence encouraging expanded URS use in facilities that do fewer operations annually.14
According to meta analysis from Ziaeefar, using medical compulsive therapy (MET) enhances stone expulsive rate while decreasing stone expulsive time.15 The use of alpha-blockers such as tamsulosin is generally used for medical compulsive treatment (MET) of distal ureteral stones in adults and children.1 Alpha-1 adrenergic receptors are the most common adrenoceptors in prostate and bladder neck tissue. The drug also has the ability to relax, dilate the intramural distal ureter, and is predicted to be able to lower ureteral peristalsis and intraluminal pressure due to the presence of alpha-1 receptors in the distal ureter. Alpha-1 adrenergic receptors are the most common adrenoceptors in the urinary tract, including the ureters.16 In the ureters, alpha-1 adrenergic receptors are distributed more distally than in the middle and proximal portions, especially the α1D subtype.17 Stimulation of α receptors increases the strength of ureteric contractions and the frequency of ureteral peristalsis. Meanwhile, the mechanism of α-antagonists includes reducing ureteral spasm, increasing proximal stone pressure, relaxing the ureter in the distal area, and reducing the tone and frequency of contractions.18-20 Due to the relaxing effect of distal ureteral tone, the preoperative use of tamsulosin may increase the successful insertion of ureteral access in children.5
A meta-analysis was prepared by Alshaikhan A, et al. on the use of pre-ureteroscopy alpha-blockers. In this study, it was concluded that the use of preoperative alpha blockers provides a high success rate of ureteroscopic access and reduces the need for ureteral dilation. In this study, there was no age limit between children and adults.21 Another study by Ahmed AF, et al. who studied the use of adjunctive tamsulosin therapy before ureteroscopy procedures in adult patients, showed that tamsulosin decreased the failure rate of ureteroscopic access, shortened the duration of surgery, and reduced
the rate of complications.22 A pooled analysis by Tan H, et al. described false lumen development, perforation, and mucosal hemorrhage as complications that may result from ureteroscopy. When compared to the placebo group, the adjunctive alpha-blocker medication was linked to a considerably reduced risk of all these complications.13 A meta analysis by Sesari SS, et al. showed that administration of adjunctive alpha blocker also minimizes colic episodes.23 In children, the lumens of the ureters are narrow, making ureteroscopy has many failures compared to adults, thus providing a more complex challenge.1,3
In the present systematic review and meta analysis study, we attempted to provide a comprehensive summary of the evidence available to assess the use of alpha blocker on the success of ureteroscopy access in pediatrics. The findings of this study may have important implications for the management of urolithiasis in pediatrics and may guide clinical decision-making regarding the use of alpha blocker preoperative in this population. In our included studies, the alpha blocker used was all tamsulosin. The studies compared patient outcomes who received tamsulosin preoperative and those who did not. There were two outcomes analyzed, the success of the initial URS attempt and the surgery length.
The meta-analysis was conducted on 3 studies involving 235 participants, comparing preoperative administration of alpha-blockers with no use of alpha- blockers showing that preoperative administration of alpha-blockers increased the success rate of ureteroscopic access. In these studies, the alpha blocker used was tamsulosin 0.4 mg with an average dose of 2-7 days before the URS procedure because tamsulosin was found to have a rapid onset of action after 8 hours when used for benign prostatic hyperplasia.3,5 Meanwhile, another research stated that administration of alpha-blockers takes at least 5 days to achieve a stable dose.16 Tamsulosin, a highly selective 1d adrenoceptor antagonist, has been shown to boost stone ejection rates for distal ureteral calculi in several studies.24 Side effects that arise as a result of the administration of tamsulosin in children can occur in the form of hypotension, asthenia, syncope, palpitations, somnolence, nausea, vomiting, headache, nasal congestion, and dizziness. Sun K, et al stated the side effects of alpha blockers were 2.3 times higher than placebo. According to further subgroup analysis, the use of tamsulosin was positively connected with adverse drug reactions (ADRs) in children with ureteral calculi, but doxazosin and silodosin had no statistically significant impact on the likelihood of treatment-emergent adverse events (TEAEs).25
Meta-analysis conducted in 2 studies showed
that preoperative administration of alpha blockers did not have a significant effect on the duration of surgery compared to without alpha blockers. Research by Demir M, et al. demonstrated that preoperative administration of tamsulosin in patients over 18 years of age resulted in a shorter operating time than those who did not receive tamsulosin.26 Other studies in populations under 18 years stated that the administration of tamsulosin before surgery did not provide significant results.1,3 The factors that can affect the duration of surgery in ureteroscopy procedures can vary. Some factors that can influence the surgery duration include stone complexity, stone size, patient’s anatomical condition, surgeon’s experience, techniques used, and available equipment. A retrospective study by Whitehurst L, et al. showed that operative times are longer while treating large, multiple stones.27 Another retrospective study by Katafigiotis I, et al. described that total stones volume, type of ureteroscope used, stone number, main surgeon experience, radio-opacity on KUB X-ray, nurse’s experience, operating room type, and having a nephrostomy tube prior to surgery were several important preoperative predicting factors that affect total operative time.28 The duration of ureteroscopy surgery can be influenced by the complexity of the stone being treated. Stones with high complexity, such as larger size or additional complications like infection or obstruction, may require a longer operating time. Additionally, stone size can also affect the surgery duration. Larger stones typically require more time to be fragmented or removed.29 A single center analysis by Ito H, et al. resulted larger stone volume, a surgeon with less expertise, higher HUs, and a lack of preoperative stenting were all shown to extend the length of the flexible URS procedure in general and the period after fragmentation begins in particular. However, it was more challenging to estimate the amount of time that would be needed to locate the stone via ureteroscopy and place the access sheath before beginning fragmentation.30 The patient’s anatomical condition can also impact the surgery duration. If the patient has anatomical abnormalities or challenging structures to access, the ureteroscopy procedure may take longer.31,32 Experienced surgeons may be more skilled in performing the procedure quickly and efficiently, thereby reducing the operating time.33-36
There are several limitations to this systematic review and meta analysis study. First, the number of studies on preoperative alpha blockers in children were small. Second, the study design was non-RCT. Third, this study only provides one type of alpha blocker, namely tamsulosin, therefore cannot analyze the effects of other alpha blockers. Fourth, the duration of administration of
alpha blockers was varied, giving rise to the potential of bias. Fifth, studies were done in only two countries which may not be representative of the general population of urolithiasis in pediatrics. Our suggestions for further research are to conduct research with a large study population with RCT study design along with preoperative alpha blockers other than tamsulosin such as silodosin and doxazosin. In addition, we suggest outcomes such as side effects, and postoperative pain reduction effects of alpha blockers in the pediatric population. Lastly, further study suggested using URS with a smaller size.
CONCLUSION
Preoperative administration of tamsulosin increases the success of ureteroscopy access in pediatrics. For the length of surgery, there was no significant difference between the use of tamsulosin as an alpha blocker with the control group.
This research did not involve human subjects; therefore, it was exempt from ethical clearance
No funding
REFERENCES
McGee LM, Sack BS, Wan J, Kraft KH. The effect of preoperative tamsulosin on ureteroscopic access in school-aged children. J Pediatr Urol. 2021;17(6):795.e1-795.e6.
Halinski A, Halinski A, Zaniew M, Kudlinski B, Soltysiak J, Sobolewski B, et al. Interest of URS-L in the treatment of ureterolithiasis in preschool children. Front Pediatr. 2019;7:324.
Khan A, Afridi AK, Khan RA, Khan, N, Nizamudin, Rashidullah
M. The effect of preoperative tamsulosin on ureteroscopic access in below 16 years children. J Saidu Med Coll Swat. 2022;12(4): 150-4.
Aldaqadossi HA, Shaker H, Saifelnasr M, Gaber M. Efficacy and safety of tamsulosin as a medical expulsive therapy for stones in children. Arab J Urol. 2015;13(2):107-11.
Morley C, Hajiran A, Elbakry AA, Al-Qudah HS, Al-Omar O. Evaluation of preoperative tamsulosin role in facilitating ureteral orifice navigation for school-age pediatric ureteroscopy. Res Rep Urol. 2020;12:563-8.
Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Syst Rev. 2021;10(1):89.
Lo CK-L, Mertz D, Loeb M. Newcastle-Ottawa Scale: comparing reviewers’ to authors’ assessments. BMC Med Res Methodol. 2014;14(1):45.
Paraboschi I, Gnech M, De Marco EA, Minoli DG, Bebi C, Zanetti SP, et al. Pediatric urolithiasis: current surgical strategies and future perspectives. Front Pediatr. 2022;10:886425.
Cao B, Daniel R, McGregor R, Tasian GE. Pediatric nephrolithiasis. Healthcare (Basel). 2023;11(4):552.
Straub M, Gschwend J, Zorn C. Pediatric urolithiasis: the current surgical management. Pediatr Nephrol. 2010;25(7):1239- 44.
Whatley A, Jones P, Aboumarzouk O, Somani BK. Safety and efficacy of ureteroscopy and stone fragmentation for pediatric renal stones: a systematic review. Transl Androl Urol. 2019;8(Suppl 4):S442-S7.
Nerli RB, Sharma M, Gupta P, Adhikari P, Bidi S, Ghagane SC. Therapeutic ureteroscopy for urolithiasis in children younger than 60 months of age. Pediatr Surg Int. 2021;37(1):145- 50.
Tan H, Li Y, Zhang X, Mao X. Pooled analysis of the efficacy and safety of adjunctive alpha-blocker therapy before ureteroscopy in the management of ureteral stones. J Int Med Res. 2020;48(6):300060520923878.
Rob S, Jones P, Pietropaolo A, Griffin S, Somani BK. Ureteroscopy for stone disease in paediatric population is safe and effective in medium-volume and high-volume centres: Evidence from a Systematic Review. Curr Urol Rep. 2017;18(12):92.
Ziaeefar P, Basiri A, Zangiabadian M, de la Rosette J, Zargar H, Taheri M, et al. Medical expulsive therapy for pediatric ureteral stones: a meta-Analysis of randomized clinical trials. J Clin Med. 2023;12(4):1410.
Yusuf M, Yogiswara N, Setiawan MR, Salsabila S, Soebadi MA, Wirjopranoto S. Preoperative alpha-blockers to facilitate ureteral access sheath (UAS) insertion: a systematic review and meta-analysis. Bali Med J. 2023;12(1):291–8.
Arrighi N, Bodei S, Zani D, Peroni A, Simeone C, Mirabella G, et al. Alpha1 Adrenoceptors in human urinary tract: expression, distribution and clinical implications. Urologia. 2007;74(2): 53-60.
Soliman MG, El-Gamal O, El-Gamal S, Abdel Raheem A, Abou- Ramadan A, El-Abd A. Silodosin versus tamsulosin as medical expulsive therapy for children with lower-third ureteric stones: prospective randomized placebo-controlled study. Urol Int. 2021;105(7-8):568-73.
Michel MC, Vrydag W. Alpha1-, alpha2- and beta-adrenoceptors in the urinary bladder, urethra and prostate. Br J Pharmacol. 2006;147 Suppl 2:S88-S119.
Yu Z-W, Wang R-H, Zhang C-C, Gao J-G. The efficacy and safety of alpha-adrenergic blockers for medical expulsion therapy in patients with ureteral calculi: a meta-analysis of placebo-controlled trials. Medicine (Baltimore). 2021;100(37): e27272.
Alsaikhan B, Koziarz A, Lee JY, Pace KT. Preoperative alpha- blockers for ureteroscopy for ureteral stones: a systematic review and meta-analysis of randomized controlled trials. J Endourol. 2020;34(1):33-41.
Ahmed AF, Maarouf A, Shalaby E, Alshahrani S, El-Feky , Khaled S, et al. Semi-rigid ureteroscopy for proximal ureteral stones: does adjunctive tamsulosin therapy increase the chance of success? Urol Int. 2017;98(4):411-7.
Sesari SS, Atmoko W, Birowo P, Rasyid N. The efficacy of
adjunctive alpha-blockers on ureteroscopy procedure for ureteral stones: a systematic review and meta-analysis. F1000Res. 2021;10:427.
Abdelaziz AS, Kidder AM. Tamsulosin therapy improved the outcome of ureterorenoscopy for lower ureteral stones: a prospective, randomised, controlled, clinical trial. African Journal of Urology. 2017;23:148-53.
Sun K, Zhang P, Sun Y, Wang Q, Xia Q. Meta-analysis of the efficacy and adverse drug reactions of adrenergic alpha- antagonists in treating children with ureteral calculi. Front. Pediatr. 2023;11:1098002.
Demir M, Ertas K, Aslan R, Eryilmaz R, Sevim M, Taken K. Does tamsulosin use before ureteroscopy increase the success of the operation? J Coll Physicians Surg Pak. 2022;32(2):197- 201.
Whitehurst L, Pietropaolo A, Geraghty R, Kyriakides R, Somani BK. Factors affecting operative time during ureteroscopy and stone treatment and its effect on outcomes: retrospective results over 6.5 years. Ther Adv Urol. 2020;12:1756287220934403.
Katafigiotis I, Sabler IM, Heifetz EM, Isid A, Sfoungaristos S, Lorber A, et al. Factors predicting operating room time in ureteroscopy and ureterorenoscopy. Curr Urol. 2019;12(4):195- 200.
Srinualnad S, Sawangchareon A, Jongjitaree K, Phinthusophon K, Taweemonkongsap T, Leewansangtong S, et al. Predictive factors of intravesical recurrence after ureteroscopy in upper urinary tract urothelial carcinoma followed by radical nephroureterectomy. Siriraj Med J. 2023;75(3):234-40.
Ito H, Kuroda S, Kawahara T, Makiyama K, Yao M, Matsuzaki J. Clinical factors prolonging the operative time of flexible ureteroscopy for renal stones: a single-center analysis. Urolithiasis. 2015;43(5):467-75.
Oofuvong M, Pattaravit N, Kanjanawanichkul O, Siripruekpong S, Nuanjun K, Suwannarat B. Are technical skills assessed using medical knowledge associated with non-technical skill knowledge in anaesthesia resident training? Siriraj Med J. 2022;74(12): 844-56.
Legemate JD, Kamphuis GM, Freund JE, Baard J, Zanetti SP, Catellani M, et al. Durability of flexible ureteroscopes: A prospective evaluation of longevity, the factors that affect it, and damage mechanisms. Eur Urol Focus. 2019;5(6):1105-11.
Berardinelli F, Cindolo L, De Francesco P, Proietti S, Hennessey D, Dalpiaz O, et al. The surgical experience influences the safety of retrograde intrarenal surgery for kidney stones: a propensity score analysis. Urolithiasis. 2017;45(4):387-92.
Wolff I, Lebentrau S, Miernik A, Ecke T, Gilfrich C, Hoschke B, et al. Impact of surgeon’s experience on outcome parameters following ureterorenoscopic stone removal. Urolithiasis. 2019; 47(5):473-9.
Chotikawanich E, Leewansangtong S, Liangkobkit K, Nualyong C, Srinualnad S, Chaiyaprasithi B, et al. The feasibility and outcomes of retrograde intrarenal surgery to treat staghorn renal calculi. Siriraj Med J. 2023;75(5):362-8.