Japanese survey of perioperative complications and ureteral stricture after ureteroscopy with laser lithotripsy for upper urinary tract stones in multicenter collaborative study.

OBJECTIVES: This study aimed to investigate perioperative complications and the details of postoperative ureteral stricture after ureteroscopy with laser lithotripsy (URS-L) for upper urinary tract stones in Japan. METHODS: Patient data on intra- and postoperative complications after ureteroscopy using URS-L were retrospectively collected from multiple centers in Japan between April 2017 and March 2020 with the cooperation of the Japanese Society of Endourology and Robotics. Data included the number of patients undergoing URS-L, number and type of intra- and postoperative complications, and detailed characteristics of postoperative ureteral stricture. RESULTS: In total, 14 125 patients underwent URS-L over 3 years at 82 institutions. Annual URS-L numbers gradually increased from 4419 in 2017, to 4760 in 2018, and 4946 in 2019. The total complication rate was 10.5%, which was divided into intra-operative complications in 1.40% and postoperative complications in 9.18%. The annual incidences of intra- and postoperative complications were not significantly different from year to year (p = 0.314 and p = 0.112). Ureteral perforation, ureteral avulsion, and the intra-operative conversion rate were 1.35%, 0.03%, and 0.02%, respectively. Fever >38°C, septic shock, blood transfusion, and postoperative mortality were 7.44%, 0.81%, 0.07%, and 0.04%, respectively. Ureteral stricture occurred in 0.8% of cases. The median length of stricture site was 10.0 mm and the success rate of stricture treatment was 54.6%. CONCLUSION: Although URS-L utilization has increased in Japan, the annual complication rate has remained steady. Although URS-L is a useful and less invasive procedure, devastating complications can still occur.

Quality of life after urinary stone surgery based on Japanese Wisconsin Stone Quality of Life questionnaire: multicenter analysis from SMART study group.

We aimed to evaluate the impact of surgical treatment for urinary stones on perioperative health-related quality of life (HRQOL) using the Japanese Wisconsin Stone Quality of Life questionnaire (J-WISQOL), an HRQOL measure designed for patients with urinary stones. This study prospectively enrolled 123 patients with urinary stones who visited three academic hospitals for stone treatment. The participants completed the J-WISQOL within 4 weeks before and after the urinary stone treatment. Treatments included shock wave lithotripsy (SWL), ureteroscopy lithotripsy, and endoscopic combined intrarenal surgery. J-WISQOL was assessed for age, stone size and location, type of treatment, stone-free status, postoperative ureteral stent placement, hospital stay, and complications in all patients. Patients with stones in the ureter had significantly greater social impact D1 and disease impact D3 than those with stones in the kidney. In a comparison of pre- and postoperative J-WISQOL, patients without postoperative ureteral stent placement scored significantly higher on social impact D1 and disease impact D3. Patients with shorter hospital stays had significantly higher social impact D1 and disease impact D3 (p < 0.001) than those with longer hospital stays. SWL significantly improved the total score, social impact D1, and disease impact D3 compared with other treatments. Perioperative HRQOL in patients with urinary stones is particularly affected by the type of treatment, ureteral stent placement, and hospital stay, which should be considered in surgical selection and patient decision-making.

Application of ultrasound imaging in the treatment of urinary tract stones.

Urinary tract stones are a common clinical condition that affect millions of individuals worldwide. The management of these stones has evolved significantly over the past 70 years, and ultrasound imaging has emerged as a valuable tool for diagnosis, treatment planning, and follow-up. This review aims to provide an overview of the application of ultrasound imaging in the treatment of urinary tract stones, highlighting its advantages, limitations, and current advancements in the field.

The Atrial Natriuretic Peptide-to-brain Natriuretic Peptide Ratio Predicts Left Atrial Reverse Remodeling after Rhythm Control Therapy in Patients with Persistent Atrial Fibrillation.

Objective The association between natriuretic peptide levels in atrial fibrillation (AF) patients with advanced left atrial (LA) remodeling and reverse remodeling after rhythm control therapy has not been clarified. The present study assessed the role of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) measurements to predict LA reverse remodeling after catheter ablation (CA) in persistent AF patients with LA enlargement. Methods This study included 88 persistent AF patients with LA enlargement (volume index >48 mL/m2) who underwent CA. Plasma ANP and BNP levels were analyzed before CA in all patients. The study population was divided into 2 groups according to the extent of decrease in the LA volume index (LAVI) at 6 months after CA responders were those with a ≥15% reduction in the LAVI, and all others were non-responders. Results At follow-up, 58 patients (66%) were classified as responders. The preprocedural ANP level was significantly higher in the responders than in the non-responders (p=0.03). Furthermore, the ANP-to-BNP ratio (ANP/BNP) was significantly higher in the responders than in the non-responders (p<0.01). The ANP/BNP was correlated with the percentage decrease in the LAVI (r=0.391, p<0.01). A multivariate linear regression analysis revealed that the ANP/BNP before CA was an independent predictor of LA reverse remodeling (p<0.01). Conclusion The preprocedural ANP/BNP was a robust predictor of reverse remodeling of the enlarged LA after sinus rhythm restoration by rhythm control therapy in persistent AF patients.

Impact of pelvicalyceal anatomical variation on surgical outcomes of endoscopic combined intrarenal surgery.

Objectives: The objective of this work is to investigate the impact of the pelvicalyceal anatomical system (PCS) on calyceal stone formation and surgical outcomes of endoscopic combined intrarenal surgery (ECIRS) for renal and/or proximal ureteral stones with a diameter >15 mm. Patients and methods: PCS was classified as Type I (single pelvis) or Type II (divided pelvis) according to the simple anatomical Takazawa classification. Using prospectively collected data from January 2016 to April 2020, 219 patients were retrospectively reviewed. After excluding patients who underwent a staged procedure, had hydronephrosis greater than grade 2, prior nephrostomy tubes, and failed to access the renal collecting system, 115 patients (Type I: 81, Type II: 34) were included, and the distribution of calyceal stones and surgical outcomes in ECIRS were compared between Types I and II PCS. Results: The median number of renal stone calyces in the Type II group was significantly more than that in the Type I group (p = 0.016). In particular, the Type II group possessed more upper stone calyces. Multivariate logistic regression analysis revealed that Type II PCS was associated with an increased odds ratio (OR) for the presence of upper stone calyces (OR: 2.93, p = 0.018). The stone-free (SF) status at 1 month after surgery, confirmed by abdominal plain radiography, was significantly higher in the Type I group compared with that in Type II (67.9% vs. 39.4%, respectively; p = 0.006). The requirement for additional surgical interventions was significantly higher in the Type II group compared with that in Type I (35.4% vs. 7.4%, respectively; p < 0.001). Multivariate analysis revealed that the number of stone calyces (OR: 4.26; p = 0.001) and Type II PCS (OR: 3.43; p = 0.009) were independent predictors of residual stones after ECIRS. Conclusion: We first revealed that the anatomic properties of PCS play a role in both upper calyceal stone formation and in the success of the ECIRS procedure. Because the SF rate in Type II PCS was significantly lower than that in Type I PCS, additional percutaneous nephrolithotomy tracts might be required, even for ECIRS.

Pelvicalyceal anatomy on the accessibility of reusable flexible ureteroscopy to lower pole calyx during retrograde intrarenal surgery.

OBJECTIVE: This study aimed to evaluate the pelvicalyceal anatomy on accessibility of reusable flexible ureteroscopy (fURS) to the lower pole calyx during retrograde intrarenal surgery (RIRS). METHODS: Here, 854 patients with ureteral or kidney stones with access to a renal collecting system using reusable fURS were classified into either the accessible group, in whom the deepest lower pole calyces could be touched; and the inaccessible group, in whom the deepest lower calyces could not be touched. We measured the infundibulopelvic angle (IPA), infundibular width (IW), infundibular length (IL), and calyceal pelvic height (CPH) using retrograde pyelograms and performed intergroup comparisons. RESULTS: The median IPA, IW, IL, and CPH in the accessible and inaccessible group were 60.5° and 45.6° (p < 0.001), 10.8 and 9.4 mm (p < 0.001), 33.2 and 36.4 mm (p < 0.001), and 25.9 and 30.9 mm (p < 0.001), respectively. IPA (OR 0.963, 95% CI 0.952-0.974, p < 0.001) and IW (OR 0.519, 95% CI 0.331-0.816, p = 0.004) were significant risk factors of renal pelvicalyceal anatomy related to the accessibility of the lower pole calyces. The cut-off value for IPA and IW was 45.8°(p < 0.001) and 7.8 mm (p < 0.001), respectively. CONCLUSIONS: IPA < 45.8° and IW <7.8 mm were negative predictors to access the lower pole calyces when using reusable fURS during RIRS.

Long-term survival of a patient with refractory advanced adrenocortical carcinoma after combination chemotherapy with paclitaxel and carboplatin plus mitotane.

Introduction: The prognosis of patients with unresectable adrenocortical carcinoma is poor. Mitotane is the first-line treatment for this disease, and etoposide/doxorubicin/cisplatin/mitotane therapy is recommended as first-line chemotherapy in unresponsive cases. We present a case of long-term survival following combination chemotherapy with paclitaxel and carboplatin plus mitotane to manage mitotane-refractory advanced adrenocortical carcinoma. Case presentation: A 49-year-old woman with a left adrenal tumor, lymph node metastasis around the aorta, and multiple liver metastases was treated with mitotane. The disease progressed despite mitotane therapy; thus, combination chemotherapy with paclitaxel and carboplatin plus mitotane was administered for 9 months. Primary adrenal resection was performed after the liver metastasis had completely dissapeared. She has remained alive for 20 years since her initial diagnosis while undergoing mitotane therapy. Conclusion: In this case, combination chemotherapy with paclitaxel and carboplatin plus mitotane effectively controlled advanced adrenocortical carcinoma.

Primary impact of simultaneous use of double devices through one-working channel when performing flexible ureteroscope with ureteral access sheath for single ureteral stone: In bench and retrospective clinical study.

OBJECTIVES: This study aimed to compare the simultaneous use of two devices versus a single device through a single working channel in flexible ureteroscopy using a ureteral access sheath for single ureteral stones. METHODS: In a bench study, the time to (i) set laser fiber, (ii) exchange laser fiber and nitinol basket through working channel, and (iii) pull out the device from working channel were measured 10 times in each step. In a clinical study, 156 patients who underwent flexible ureteroscopy with a ureteral access sheath for a ureteral stone in middle and upper ureter between April 2019 and November 2021 were assessed. One device was used at a time for 79 patients (S-Group) and two were simultaneously used for 77 (D-Group). Surgical outcomes and complications were compared. RESULTS: In the bench study, the mean time to change from laser fiber to basket and from basket to laser fiber through the working channel were 26.1 ± 3.7 s and 23.6 ± 2.0 s (p = 0.084), respectively, which were significantly longer than the laser setup time (p < 0.001). In the clinical study, although the stone-free rate was not significantly different between the groups (S-Group 89.8%, D-Group 93.5%; p = 0.412), the median operation time was significantly shorter (p < 0.001) and the rate of postoperative stenting was significantly lower (p = 0.002) in the D-Group. There were no significant between-group differences in intra- and post-operative complications. CONCLUSION: The simultaneous use of two devices through a single working channel is safe and could help save the time needed to exchange the laser fiber and nitinol basket.

Microbial differences between active and remission peri-implantitis.

Peri-implantitis has a polymicrobial etiology and is a major cause of dental implant loss. Various clinical protocols for its prevention and treatment have been proposed; however, some cases show a rapid progression with non-resolving clinical symptoms. To clear a means of differentiating between such cases, the implants with peri-implantitis in this study were categorized as the active group and the remission group and that two kinds of samples were obtained from the same subjects (n = 20). The microbiome was analyzed through pyrosequencing of the 16S rRNA gene. From LEfSe results, Porphyomonas, Fusobacterium, Treponema, Tannerella, and other periodontal pathogens were abundant in the active group, while lactic acid bacteria (Lactobacillales and Bifidobacterium) were abundant in the remission group.

Evaluating Predictive Factor of Systemic Inflammatory Response Syndrome and Postoperative Pain in Patients Without Ureteral Stent Placement After Ureteral Access Sheath Use in Flexible Ureteroscopy for Stone Management.

Background and Objective: This retrospective cohort study aimed to evaluate the safety of stentless flexible ureteroscopy (fURS) using a ureteral access sheath (UAS) for stone management. Patients and Methods: A total of 270 ureteral stentless postoperative patients were analyzed. Stentless indication was characterized by having no ureteral wall or mucosa injury with only slight erosion, <1 hour operative time, and no endoscopic stone fragments with or without stone dust. Postoperative complications and pain were analyzed for safety measurements. In addition, preoperative and intraoperative risk factors associated with the incidence of systemic inflammatory response syndrome (SIRS) and postoperative pain were evaluated. Results: The most common UAS sizes were 10/12F (69.6%) and 9.5/11.5F (28.1%). The rate of patients who were stone free was 95.9%. The median operation time was 34 minutes. Only three grade 1 ureteral injuries occurred intraoperatively. Postoperative SIRS occurred in 8.8% of patients, and postoperative use of analgesics was 35.9%. Only four patients were required to undergo eventual ureteral stenting. Less than 10/12F UAS was the only factor positively associated with preventing postoperative SIRS (odds ratio [OR], 4.733; 95% confidence interval [CI], 1.085-20.644). Older age and preoperative ureteral stenting were positively associated with preventing postoperative pain (OR, 0.970; 95% CI, 0.951-0.990 and OR, 0.427; 95% CI, 0.232-0.786; respectively). Conclusion: Stentless fURS with UAS in stone management was feasible for selected patients. UAS size of <10/12F, older age, and preoperative stenting are possible keystones to achieving stentless fURS with UAS postoperatively. IRB approval number; 20216101.

Single-Session Impact of High-Power Laser with Moses Technology for Lower Pole Stones in Retrograde Intrarenal Surgery: Retrospective Study.

Background: This study aimed to evaluate the efficacy of a high-power holmium laser with Moses technology (MT) for the treatment of lower pole stones during retrograde intrarenal surgery (RIRS). Methods: Herein, 305 patients with lower pole stones who underwent RIRS using a high-power holmium laser with MT were retrospectively classified into the stone-free (SF) and non-SF groups. We measured the stone burden, stone volume, stone hardness, pre- or post-operative stent placement, infundibulopelvic angle (IPA), infundibular width (IW), infundibular length (IL), and calyceal pelvic height in terms of pelvicalyceal anatomy using retrograde pyelograms and evaluated the predictive factors of postoperative SF. Results: A total of 173 (56.7%) and 229 (75.1%) patients achieved a SF status on postoperative day one and at one month, respectively. Operation time in the SF group was shorter than that in the non-SF group (51.0 vs. 74.5 min). There were no significant differences in postoperative complications between the SF and non-SF groups. Significantly predictive risk factors in postoperative SF included total stone volume (odds ratio (OR), 1.056; 95% CI, 1.015-1.099; p = 0.007), IPA (OR, 0.970; 95% CI, 0.956-0.993; p = 0.009), and IW (OR, 0.295; 95% CI, 0.121-0.718; p = 0.007). The cut-off values of stone volume, IPA, and IW were 515.2 mm3, 46.8°, and 7.75 mm, respectively. Conclusions: A high-power holmium laser with MT in lower pole stones is a valuable option for positive outcomes and patient's safety. Larger stone volume, acute IPA, and narrow IW were negative predictors related to postoperative SF status.

Comparison of the safety and efficacy between the prone split-leg and Galdakao-modified supine Valdivia positions during endoscopic combined intrarenal surgery: A multi-institutional analysis.

OBJECTIVES: To evaluate the safety and efficacy of the prone split-leg and the Galdakao-modified supine Valdivia positions during endoscopic combined intrarenal surgery. METHODS: A multi-institutional, retrospective cohort study was conducted between January 2014 and December 2018. The stone-free and complication rates were compared between the prone split-leg and the Galdakao-modified supine Valdivia positions. Anatomical variations were evaluated using contrast-enhanced computed tomography imaging. RESULTS: In total, 118 and 100 patients underwent endoscopic combined intrarenal surgery in the prone split-leg and Galdakao-modified supine Valdivia positions, respectively. Renal punctures in the prone split-leg position were predominantly executed through the lower calyces (78.0%), whereas those in the Galdakao-modified supine Valdivia position were primarily performed through the middle calyces (64.0%; P < 0.001). Surgical duration in the prone split-leg position was significantly shorter than that in the Galdakao-modified supine Valdivia position (106.5 vs 126.0 min; P = 0.0459). There were no significant differences in the stone-free rate between the two positions (78.8% vs 76.0%; P = 0.629). Incidences of urinary tract injury (P = 0.033) and febrile urinary tract infection (23.7% vs 10.0%; P = 0.011) in the prone split-leg position were significantly higher than that in the Galdakao-modified supine Valdivia position. The tilt of the major renal axis was significantly greater in the prone position than the corresponding values in the oblique position (19.4° vs 8.5°; P = 0.019). CONCLUSIONS: Anatomical variation might result in the differences of renal puncture calyx. Endoscopic combined intrarenal surgery in the Galdakao-modified supine Valdivia position may bring equal stone-free status, with a longer surgical time but fewer complications including febrile urinary tract infection and urinary tract injury than the prone split-leg position.

Validation of the Japanese Version of The Wisconsin Stone Quality of Life Questionnaire: Results from SMART Study Group.

Background: The Wisconsin Stone Quality of Life questionnaire (WISQOL) is a health-related quality of life (HRQOL) measure designed for patients with urinary stones. It has been translated and used in several languages. This study aimed to validate the Japanese version of the WISQOL (J-WISQOL). Materials and Methods: The J-WISQOL was translated and validated using a multistep process proposed by the World Health Organization that involved forward translation, back-translation, and pilot testing with a group of patients. This study enrolled 150 patients with urinary stones who visited three academic hospitals for stone treatment. We assessed convergent validity of correlation patterns and internal consistency of the J-WISQOL and Short-Form 36-item survey version 2 (SF-36v2). Results: Overall, 150 patients were enrolled. The mean total score of the J-WISQOL was 108.18 ± 20.26 (raw score min-max, 28-140), suggesting that the onset and symptoms of urinary stones reduced the HRQOL in the patients. The J-WISQOL showed good internal consistency (Cronbach's α = 0.96) and interdomain associations (Spearman's correlation coefficient r = 0.67-0.94). The J-WISQOL was correlated with the SF-36v2 in all domains: social, emotional, health, and vitality impact (r = 0.47-0.66). Conclusion: The J-WISQOL is a reliable instrument for evaluating HRQOL measures in patients with urinary stones. It could be a useful quality of life questionnaire for urinary stones in Japan. Clinical Trial 60-20-0047.

One- versus two-surgeon active stone retrieval procedures for flexible ureteroscopy: An off-site simulator comparative study.

OBJECTIVES: To evaluate the efficacy of the one-surgeon basketing technique compared to the conventional two-surgeon method for flexible ureteroscopy. METHODS: Seven urologists (three trained and four less-trained surgeons) extracted three renal stones using each technique with an off-site simulator. We analyzed the task completion time, the number of times the basket forceps were opened and closed, and unexpected events during stone-catching, for both techniques. RESULTS: There was no significant difference in the total task completion time between the one-surgeon (102.0 [interquartile range 63.5-164.0] s) and two-surgeon (99.5 [interquartile range 75.0-145.3] s) techniques. However, the time it took the trained surgeons to extract all stones was significantly shorter with the one-surgeon than with the two-surgeon technique (19.0 [interquartile range 18.0-20.0] s vs 34.0 [interquartile range 25.0-40.0] s; P = 0.049). Among the less-trained surgeons, the opposite effect was observed, but this difference was not statistically significant (96.5 [interquartile range 61.0-134.5] s vs 64.0 [interquartile range 51.5-77.0] s; P = 0.489). The number of times the forceps were opened and closed during stone-catching was significantly lower with the one-surgeon technique than with the two-surgeon technique (5.0 [interquartile range 4.0-5.0] times vs 9.0 [interquartile range 6.0-14.5] times; P = 0.018). CONCLUSIONS: The one-surgeon technique can offer comparable efficacy to the two-surgeon technique. If surgeons are sufficiently trained, a one-surgeon basketing technique for performing flexible ureteroscopy might become a new technical modality for extracting renal stones.

Retrograde intrarenal surgery: Past, present, and future.

With the recent technological advancements in endourology, retrograde intrarenal surgery has become a more popular procedure for treatment of urolithiasis. Furthermore, since the introduction of new laser systems and advanced flexible ureteroscopy with miniaturized ureteroscopes, the treatment indications for retrograde intrarenal surgery have expanded to include not only larger renal stones of >2 cm but also upper urinary tract urothelial carcinoma, ureteral stricture, and idiopathic renal hematuria. Clinicians must keep up with these trends and make good use of these technologies in the rapidly changing field of endourology. Simultaneously, we must consider the risk of various complications including thermal injury due to laser use, ureteral injury caused by the ureteral access sheath, and radiation exposure during retrograde intrarenal surgery with fluoroscopic guidance. This review focuses on the past, present, and future of retrograde intrarenal surgery and provides many topics and clinical options for urologists to consider.

Bone turnover markers to assess jawbone quality prior to dental implant treatment: a case-control study.

BACKGROUND: Bone quality is as important as bone mineral density in terms of bone strength. Bone turnover markers (BTMs) are clinical indicators of bone quality. In implant dentistry, bone quality is considered equivalent to bone density on radiographic assessments. The purpose of this study was to determine whether the BTM values are reflected in jawbone condition by evaluating the relationship at baseline and during follow-up in patients with prosthodontic implants. Computed tomography (CT) scans were obtained and BTM (osteocalcin, bone-specific alkaline phosphatase, pyridinoline cross-linked carboxyterminal telopeptide of type I collagen, and crosslinked N-telopeptide of type I collagen) levels in blood samples were measured in partially edentulous eighteen patients before implant surgery. During the follow-up observation after implant surgery, marginal bone loss (MBL) was measured on dental radiography. We investigated the relationship between the presence of BTM abnormalities and radiographic bone density. RESULTS: More women than men had abnormal BTM values. Bone turnover was accelerated in the group of women with abnormal BTM values. The density of cancellous bone at the implant placement site was significantly lower in the patients with abnormally high BTM values than in their counterparts with BTM values in the normal range. CONCLUSIONS: Female patients who undergo implant treatments may have reduced bone quality; evaluations of bone strength will require assessments of both BTMs and the density of cancellous bone.

Prospective evaluation and classification of endoscopic findings for ureteral calculi.

Difficulty in performing ureteroscopic lithotripsy (URSL) depends on endoscopic findings surrounding calculi. In this multicentre prospective cohort study of 185 patients with a single ureteral stone who underwent ureteroscopic lithotripsy registered in the SMART study between January 2014 and February 2017, we established a classification of endoscopic findings and analysed risk factors for ureteral changes. We evaluated endoscopic findings (oedema, polyps, ureteral mucosa-stone adherence, and distal ureteric tightness) based on the SMART classification. Operative time and ureteral injuries were significantly correlated with endoscopic finding grades. Multivariate analyses revealed that mucosa-stone adherence (MSA) was strongly affected by hydronephrosis grade (odds ratio, 12.4; p = 0.022) and the interval before surgery (odds ratio, 1.10; p = 0.012). The cutoff value for MSA was 98 days, with a predictive accuracy of 0.78. Risk factors for distal ureteric tightness were age (odds ratio, 0.96; p = 0.004) and early intervention (odds ratio, 0.90; p = 0.023). The cutoff value was 34 days, with a predictive accuracy of 0.72. In conclusion, appropriate intervention around 34 days (limited to 98 days) after symptom onset is necessary for treating ureteral calculi. Even if intervention passed 98 days post-symptom onset, staged URSL, alternative procedures, and detailed informed consent should be planned in advance, assuming strong MSA.

Change in irrigation flow through a flexible ureteroscope with various devices in the working channel: Comparison between an automatic irrigation pump and gravity-based irrigation.

OBJECTIVES: To evaluate the change in the irrigation flow with various instruments in the working channel of a flexible ureteroscope by two automatic irrigation pumps and gravity-based irrigation in an ex vivo setting. METHODS: We used two automatic irrigation pumps: the Endoflow II and the UROMAT Endoscopic Automatic System for Irrigation and gravity-based irrigation. A flexible ureteroscope was connected to an irrigation tube with a working channel. The other side of the irrigation tube was attached to each automatic irrigation pump, which was connected with a 2-L saline bag or to a 2-L saline bag directly in case of gravity pressure. The flow volume from the working channel was measured three times for 30 s at various irrigation pressure settings, both when the working channel was unoccupied and occupied with various instruments. RESULTS: The irrigation flow steadily increased as the irrigation pressure in the automatic irrigation pumps increased and the saline position in gravity became higher (P < 0.05). However, the flow decreased as the size of the instrument in the working channel increased (P < 0.05). The efficiency of irrigation flow in gravity-based irrigation under the same pressure is significantly lower than one of two automatic irrigation pumps (P < 0.05). However, there was no significant difference in the efficiency of the irrigation flow between the Endoflow II and UROMAT Endoscopic Automatic System for Irrigation. The irrigation pressure setting needed to change to maintain adequate irrigation flow when using various working tools. CONCLUSIONS: The efficiency of irrigation flow in gravity-based irrigation is significantly lower than one of two automatic irrigation pumps. The irrigation flow decreases as the size of the instrument in the working channel increases.