Evaluation of renovated double J stents using ureter models with and without stenosis.

PURPOSE: Commercial double J stents (DJS) have a uniform shape regardless of the specific nature of various ureteral diseases. We tested renovated DJS and compared them with conventional DJS using ureter models. METHODS: One straight ureter model included stenosis at the distal ureter near the ureterovesical junction and the other did not. We used conventional DJS and renovated 5- and 6-Fr soft DJS for ureter stones and 6-, 7-, and 8.5-Fr hard DJS for tumors. The DJS comprised holes in the upper, middle, or lower one-third of the shaft (length, 24 cm; 2-cm-diameter coils at both ends). More holes were created along the shaft based on the ureteral disease location. Conventional DJS had holes spaced 1 cm apart along the shaft. Renovated DJS had holes spaced 1 cm apart along the shaft with 0.5-cm intervals on the upper, middle, or lower one-third of the shaft. Urine flow was evaluated. RESULTS: As the DJS diameter increased, the flow rate decreased. The flow rates of DJS with holes in the lower shaft were relatively lower than those of conventional DJS and DJS with holes in the upper and middle shafts. In the ureter model without stenosis, 6-, 7-, and 8.5-Fr renovated stents exhibited significantly higher flow rates than conventional stents. In the ureter model with stenosis, 5-, 6-, 7-, and 8.5-Fr renovated stents did not exhibit significantly higher flow rates than conventional stents. CONCLUSION: Renovated stents and conventional stents did not exhibit significant differences in urine flow with stenosis.

Optimal thrombin injection method for the treatment of femoral artery pseudoaneurysm.

BACKGROUND: Iatrogenic femoral artery pseudoaneurysm (IFP) incidence is increasing with increase in diagnostic and therapeutic angiography, and so, the less invasive percutaneous thrombin injection (PTI) is the most widely used treatment. Moreover, studies that minimize PTI complications and highlight therapeutic effects are lacking. OBJECTIVES: This study performed in vitro thrombosis modeling of pseudoaneurysms and analyzed thrombosis within and thromboembolism outside the sac during thrombin injection. METHODS: We evaluated PTI in terms of thrombin injection location (at the junction of the IFP sac and neck, the center, and the dome, located farthest from the neck of the sac), thrombin injection time (5 and 8 seconds), and blood flow rate (ranging from 210 mL/min to 300 mL/min). Porcine blood was used as the working fluid in this study. RESULTS: Thrombin injection at the junction of the IFP sac and the pseudoaneurysm neck led to less thrombosis within the sac but substantial thrombi consistently outside the sac, whereas thrombin injected at the sac center mostly led to complete thrombosis within the sac, preventing further blood flow into the sac and reducing likelihood of thrombi outside the sac. A longer thrombin injection time enhanced the therapeutic effect and decreased the possibility of thromboembolism. Thromboembolism occurred more frequently at flow rates of >240 mL/min. CONCLUSION: The thrombin injection site in a pseudoaneurysm significantly influences thrombogenesis within and thromboembolism outside the sac. Thus, slow and deliberate injection of thrombin into the center of the sac could potentially reduce complications and enhance treatment efficacy.

Effects of size and shape of the side holes of a double J stent on the ureter fluid flow after stenosis.

The effect of side holes morphology changes in double J stent (DJS) on encrustation was analyzed using computational fluid dynamics (CFD). We analyzed DJS side holes with inner diameter of 1 mm and outer diameters of 1 (type A), 1.2 (type B) and 1.4 (type C) mm, respectively. Concentric stenosis with three intraureteral degree (0%, 12%, and 88%) was analyzed. The flow rate, shear stress and wall shear stress (WSS) distribution were investigated. Urine flow through SH1 before the ureteropelvic junction (UPJ) differed based on the ureteral stenosis degree. The sum of flow rates through the SHs increased with diameter. In the stented ureter with 12% stenosis, the flow rate through SH1 approximately doubled than that without ureteral stenosis, and the flow rate through SH1 was maximal for the type 'C' stent in both 12% and 88% ureteral stenosis. The mean shear stress in the SHs increased with the degree of stenosis. The WSS around the SHs was higher for type 'C' than types A and B. From the flow rates and shear stresses in and around the SHs, the larger SH diameter of the DJS from the UPJ to mid-ureter is expected to induce encrustation reduction, especially in patients with urinary lithiasis.

Evaluation of encrustation of double J stents with artificial urine.

PURPOSE: To evaluate the formation of encrustation on double J stents (DJSs) using artificial urine. MATERIALS AND METHODS: In this study, a static urinary system containing artificial urine was created, and a total of 45 DJSs were used to evaluate the formation of encrustation. Three groups of 15 DJSs were tested for 4, 8, or 14 weeks. The formation of encrustation on the DJSs over the weeks was analyzed using methods including X-ray powder diffraction (XRD), inductively coupled plasma spectrophotometer (ICP), and scanning electron microscope (SEM). Statistical analysis and the uncertainty test were used for data analysis using R language. RESULTS: The ICP analyzed the weight of the calcium and magnesium, which are the major components of urinary stones and encrustation, and showed that it was the heaviest at 14 weeks. Measurement of the area of encrustation on the outer surface of the DJSs revealed that the encrustation area at the bottom of the stent was greater than that at the top of the stent, regardless of the experimental period (proximal part: ≤ 41,099 µm2, distal part: ≤ 183,259 µm2). Encrustation occurred around the side holes of DJSs and became bigger over time to fill up the side holes. CONCLUSION: Encrustation spots included the bottom zone of the DJS and around the side holes. These results indicate that the performance of DJSs would be improved by modifying the shape of DJSs located near the bladder and side holes.

Temporal changes of PIRADS scoring by radiologists and correlation to radical prostatectomy pathological outcomes.

Purpose: To assess temporal improvement of prostate image reporting and data system (PIRADS) 3-5 lesion correlation to histopathologic findings from radical prostatectomy (RP) in prostate cancer (PCa). Materials and methods: A total of 1481 patients who underwent RP for biopsy-proven PCa between 2015 and 2019 were divided into 14 groups of 100 sequential readings for the evaluation of histopathological correlation with PIRADS readings. Temporal trends of PIRADS distribution and predictive performance for RP pathology were evaluated to assess underlying changes in prostate magnetic resonance imaging (MRI) interpretation by radiologists. Results: PIRADS 4-5 lesions were significantly correlated with the increasing rates of Gleason Group (GG) upgrade (p = 0.044) and decreasing rate of GG downgrade (p = 0.016) over time. PIRADS ≥3 lesions read after median 2 years of experience were shown to independently predict intermediate-high-risk (GG ≥ 3) PCa (odds ratio 2.93, 95% confidence interval 1.00-8.54; P= 0.049) in RP pathology. Preoperative GG ≥ 3 biopsy lesions with PIRADS 4-5 lesions were significantly more susceptible to GG upgrade (P= 0.035) and GG ≥ 4 RP pathology (p = 0.003) in experienced reads, in contrast to insignificant findings in early readings (p = 0.588 and 0.248, respectively). Conclusion: Preoperative MRI reports matched with RP pathology suggest an improved prediction of adverse pathology in PIRADS 3-5 lesions over time, suggesting a temporal change in PIRADS interpretation and predictive accuracy. Institutions with low volume experience should use caution in solely relying on MRI for predicting tumor characteristics. Future prospective trials and larger scale assessments are required to further validate our results.

CFD study on vesicoureteral reflux in the urinary tract with double J stent.

OBJECTIVE: This study investigates the effects of vesicoureteral reflux (VUR) in the upper and lower urinary tracts with and without ureteral stenosis and with a double J stent (DJS). METHODS: The entire length of the urinary tract with an implanted DJS was modeled. To assess the possibility of VUR, the measured values were used as boundary conditions for the baseline, the maximum cystometric bladder capacity (MCBC) during the filling phase, and maximum vesical pressure during the voiding phase were computed. The flow rates, flow patterns, wall shear stress (WSS) distribution, impact force induced by reflux urination, and helicity of the bladder were investigated for the urinary system. RESULTS: The flow from the bladder to the renal pelvis was detected at maximum vesical pressure (75 cmH2O) during the voiding phase, and a small amount (1.09 mL/s) of VUR was noted at the MCBC during the filling phase. The WSS increased when the reflux was large. Helicity within the bladder varied with the stenosis as well as opening and closing of the urethra. The reflux within the stent was reduced by 40% by inserting a ball into the stent. CONCLUSION: The main VUR factor was the opening and closing of the vesicoureteric junction by the detrusor muscle. The largest urine reflux (11.7 mL/s) to the kidney occurred when the detrusor muscle was relaxed. SIGNIFICANCE: Ureteral stenosis affected the VUR and reduced urine reflux. Ball insertion in the stent reduced urine reflux through the stent lumen.

Urine flow analysis using double J stents of various sizes in in vitro ureter models.

A double J stent (DJS) is used to alleviate the congestion of urine in the upper urinary tract when there is ureteral stenosis, which causes the interruption of normal urine flow and results in renal failure. The purpose of placing DJSs is to ensure sufficient urine flow in the ureter, but the DJS acts as a foreign body in the urinary system and sometimes acts as an obstacle in achieving sufficient urine flow. Here, to evaluate the performance of various sizes of DJSs, 5Fr (1.666 mm) to 8Fr (2.666 mm), in the ureter, silicon ureter models without stenosis, and a circulation setup were constructed. The total flow rates (TFRs) in the stented ureters were evaluated with an in vitro experiment. The TFRs in the 5Fr DJS were larger than those in the other sizes of DJS. As the size of DJS increased, the TFR decreased. Computational fluid dynamics was also applied to validate the experimental results. It was shown that the experimental results agreed well with the numerical results.

The ethanol extract of Aquilariae Lignum ameliorates hippocampal oxidative stress in a repeated restraint stress mouse model.

BACKGROUND: Chronic stress contributes to the development of brain disorders, such as neurodegenerative and psychiatric diseases. Oxidative damage is well known as a causative factor for pathogenic process in brain tissues. The aim of this study is to evaluate the neuroprotective effect of a 30% ethanol extract of Aquilariae Lignum (ALE) in repeated stress-induced hippocampal oxidative injury. METHODS: Fifty BALB/c male mice (12 weeks old) were randomly divided into five groups (n = 10). For 11 consecutive days, each group was orally administered with distilled water, ALE (20 or 80 mg/kg) or N-acetylcysteine (NAC; 100 mg/kg), and then all mice (except unstressed group) were subjected to restraint stress for 6 h. On the final day, brain tissues and sera were isolated, and stress hormones and hippocampal oxidative alterations were examined. We also treated lipopolysaccharide (LPS, 1 µg/mL)-stimulated BV2 microglial cells with ALE (1 and 5 µg/mL) or NAC (10 µM) to investigate the pharmacological mechanism. RESULTS: Restraint stress considerably increased the serum levels of corticosterone and adrenaline and the hippocampal levels of reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA). ALE administration significantly attenuated the above abnormalities. ALE also significantly normalized the stress-induced activation of astrocytes and microglial cells in the hippocampus as well as the elevation of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1ß). The in vitro assay outcome supplemented ALE could dramatically block NF-κB activation in microglia. The anti-oxidative stress effects of ALE were supported by the results of antioxidant components, 4-hydroxynonenal (4-HNE), NADPH oxidase 2 (NOX2), inducible nitric oxide synthase (iNOS) and NFE2L2 (Nrf2) in the hippocampal tissues. CONCLUSIONS: We firstly demonstrated the neuroprotective potentials of A. Lignum against hippocampal oxidative injury in repeated restraint stress. The corresponding mechanisms might involve modulations in the release of ROS, pro-inflammatory cytokines and stress hormones.

Numerical analysis of urine flow through the side holes of a double J stent in a ureteral stenosis.

Ureteral stenosis presents with a narrowing in the ureter, due to an intrinsic or extrinsic ureteral disease, such as ureter cancer or retroperitoneal fibrosis. The placement of a double J stent in the upper urinary system is one of the most common treatments of ureteral stenosis, along with the insertion of a percutaneous nephrostomy tube into the renal pelvis. The effect that the side holes in a double J stent have on urine flow has been evaluated in a few studies using straight ureter models. In this study, urine flow through a double J stent's side holes was analyzed in curved ureter models, which were based on human anatomy. In ureteral stenosis, especially in severe ureteral stenosis, a stent with side holes had a positive effect on the luminal and total flow rates, compared with the rates for a stent without side holes. The more side holes a stent has, the greater the luminal and total flow rates. However, the angular positions of the side holes did not affect flow rate. In conclusion, the side holes in a double J stent had a positive effect on ureteral stenosis, and the effect became greater as the ureteral stenosis became more severe.

Effects of naftopidil on double-J stent-related discomfort: a multicenter, randomized, double-blinded, placebo-controlled study.

To evaluate the effect of naftopidil 75 mg once daily for ureteral double-J (DJ) stent-related discomfort after a ureteroscopic procedure using a multicenter, randomized, double-blinded, placebo-controlled study. 100 patients with indwelled retrograde DJ ureteral stents after ureteroscopic stone removal or retrograde intrarenal surgery (RIRS) were randomized 1:1 to receive either placebo or naftopidil during the stenting period. At the time of stent removal, the Ureteral Stent Symptom Questionnaire (USSQ), the International Prostate Symptom Score and the total amount of used analgesics were reported. Of the 92 patients who completed the study, 49 patients were enrolled in the placebo group, and 43 patients in the naftopidil group. USSQ urinary symptom scores (30.90 vs. 29.23, p = 0.299) and USSQ body pain scores (22.28 vs. 19.58, respectively, p = 0.286) were lower in the naftopidil group than in the placebo group, but the difference was not significant. Multivariate analysis showed that the use of a ureteral access sheath during RIRS was the only significant predictor of postoperative DJ-related pain (OR = 2.736, p = 0.031). The use of naftopidil once daily did not significantly reduce DJ ureteral stent-related discomfort. Larger-scaled prospective studies should be conducted to evaluate the effects of naftopidil on DJ stent-related symptoms and surgeries.

Analysis of Urine Flow in Three Different Ureter Models.

The ureter provides a way for urine to flow from the kidney to the bladder. Peristalsis in the ureter partially forces the urine flow, along with hydrostatic pressure. Ureteral diseases and a double J stent, which is commonly inserted in a ureteral stenosis or occlusion, disturb normal peristalsis. Ineffective or no peristalsis could make the contour of the ureter a tube, a funnel, or a combination of the two. In this study, we investigated urine flow in the abnormal situation. We made three different, curved tubular, funnel-shaped, and undulated ureter models that were based on human anatomy. A numerical analysis of the urine flow rate and pattern in the ureter was performed for a combination of the three different ureters, with and without a ureteral stenosis and with four different types of double J stents. The three ureters showed a difference in urine flow rate and pattern. Luminal flow rate was affected by ureter shape. The side holes of a double J stent played a different role in detour, which depended on ureter geometry.

Comparison of the Efficacy and Safety of Laparoendoscopic Single-Site Surgery with Conventional Laparoscopic Surgery for Upper Ureter or Renal Pelvis Stones in a Single Institution: A Randomized Controlled Study.

PURPOSE: To evaluate the utility and safety of laparoendoscopic single-site surgery (LESS) in comparison with conventional laparoscopic (CL) surgery for the treatment of upper urinary tract stones. MATERIAL AND METHODS: Between June 2011 and May 2012, 20 patients with upper urinary tract stones were included in this prospective randomized study. The patients were assigned into the LESS group or CL group in a one-on-one manner using a random table. The clinical parameters were evaluated in the immediate postoperative period, and the stone clearance rate was evaluated via non-contrast computer tomography at one month postoperatively. RESULTS: There were no significant differences in patient demographics or preoperative stone sizes between the two groups. The perioperative parameters, including operative time, estimated blood loss, postoperative pain scores, length of hospital stay, and changes in renal function, were comparable. No transfusions or open conversions were required in either group. The incidence of residual stones was lower in the LESS group (1 case) than in the CL group (2 cases). However, this difference was not statistically significant. CONCLUSIONS: For large and impacted upper ureteral stones, the effectiveness and safety of LESS were equivalent to those of CL. Further randomized control trials with larger sample sizes are needed to strengthen the conclusions of this study. .

Antifungal Activity of Bee Venom and Sweet Bee Venom against Clinically Isolated Candida albicans.

OBJECTIVES: The purpose of this study was to investigate the antifungal effect of bee venom (BV) and sweet bee venom (SBV) against Candida albicans (C. albicans) clinical isolates. METHODS: In this study, BV and SBV were examined for antifungal activities against the Korean Collection for Type Cultures (KCTC) strain and 10 clinical isolates of C. albicans. The disk diffusion method was used to measure the antifungal activity and minimum inhibitory concentration (MIC) assays were performed by using a broth microdilution method. Also, a killing curve assay was conducted to investigate the kinetics of the anti- fungal action. RESULTS: BV and SBV showed antifungal activity against 10 clinical isolates of C. albicans that were cultured from blood and the vagina by using disk diffusion method. The MIC values obtained for clinical isolates by using the broth microdilution method varied from 62.5 µg/ mL to 125 µg/mL for BV and from 15.63 µg/mL to 62.5 µg/mL for SBV. In the killing-curve assay, SBV behaved as amphotericin B, which was used as positive control, did. The antifungal efficacy of SBV was much higher than that of BV. CONCLUSION: BV and SBV showed antifungal activity against C. albicans clinical strains that were isolated from blood and the vagina. Especially, SBV might be a candidate for a new antifungal agent against C. albicans clinical isolates.

An Inductively-Powered Wireless Neural Recording System with a Charge Sampling Analog Front-End.

An inductively-powered wireless integrated neural recording system (WINeR-7) is presented for wireless and battery less neural recording from freely-behaving animal subjects inside a wirelessly-powered standard homecage. The WINeR-7 system employs a novel wide-swing dual slope charge sampling (DSCS) analog front-end (AFE) architecture, which performs amplification, filtering, sampling, and analog-to-time conversion (ATC) with minimal interference and small amount of power. The output of the DSCS-AFE produces a pseudo-digital pulse width modulated (PWM) signal. A circular shift register (CSR) time division multiplexes (TDM) the PWM pulses to create a TDM-PWM signal, which is fed into an on-chip 915 MHz transmitter (Tx). The AFE and Tx are supplied at 1.8 V and 4.2 V, respectively, by a power management block, which includes a high efficiency active rectifier and automatic resonance tuning (ART), operating at 13.56 MHz. The 8-ch system-on-a-chip (SoC) was fabricated in a 0.35-µm CMOS process, occupying 5.0 × 2.5 mm2 and consumed 51.4 mW. For each channel, the sampling rate is 21.48 kHz and the power consumption is 19.3 µW. In vivo experiments were conducted on freely behaving rats in an energized homecage by continuously delivering 51.4 mW to the WINeR-7 system in a closed-loop fashion and recording local field potentials (LFP).

Do Effects on Bowel Patterns Imposed by Solifenacin Always Have Negative Impacts on Treating Patients with Overactive Bladder (OAB)?

OBJECTIVES: To investigate whether solifenacin intervention leads to any changes in bowel symptoms, and the types of impacts imposed on bowel symptoms in patients with overactive bladder (OAB). METHODS: This prospective, single-arm observational study included 40 adult patients who underwent anticholinergic treatment for OAB. Outcome measures were determined by examining differences in voiding and bowel symptoms, before and after patients commenced anticholinergic therapy. Patients were evaluated at baseline, 4, and 12 weeks via questionnaires on OAB and irritable bowel syndrome (IBS), side-effects, and overall satisfaction with the treatment. RESULTS: A total of 22 patients completed follow-up visits. Mean age was 62.1 ± 10.3 years. The most common side-effects were constipation and dry mouth. OAB symptom scores improved, with significant changes in urgency, incontinence, and total symptom scores and borderline significant changes in frequency. All bowel symptoms except diarrhea became aggravated. Average constipation and overall quality of life worsened with significance. Aside from the specific bowel habit changes, solifenacin treatment resulted in changes in patient status of IBS, as well. Patients were mostly satisfied with the treatment, despite some aggravations in discomfort due to defecation problems. CONCLUSIONS: This study shows that solifenacin treatment is effective for treating urinary incontinence but may lead to changes in bowel patterns and affects overall quality of life (QoL). Effects on bowel patterns imposed by solifenacin can be positive or negative, therefore, physicians should consider more holistic therapy by addressing overall bowel symptoms when treating OAB patients.

A New Sliding-Loop Technique in Renorrhaphy for Partial Nephrectomy: A Feasibility Study in a Porcine Model.

BACKGROUND: We developed a sliding-loop technique that narrowed both sides of the parenchyma in a porcine model and compared it with the conventional sliding-clip technique. METHODS: Three pigs (30-40 kg) were reused following another experiment conducted by the same researchers. Bilateral kidneys were harvested within 30 minutes after euthanasia. Two partial nephrectomies per kidney were performed on opposite surfaces. All kidney defects were of the same size (diameter of 2.5-3 cm with a depth of 1.0-1.5 cm). The sliding-clip technique and sliding-loop technique were performed separately. In the sliding-loop technique, we created a 1-cm loop at the end of a Vicryl and placed a tetrafluoroethylene polymer pledget in front of the knots passing through the needle. The needle then crossed the loop after passing through the renal parenchyma. A Weck clip was placed and slid on one side to tighten the suture. Tightening was controlled with an equivalent force using a digital push-pull gauge. Three stitches were placed at each renorrhaphy site. The distance between repaired renal surfaces was measured at 5 different points (3 suture sites and 2 middle sites between sutures). RESULTS: The results of the 2 techniques were compared by using the independent t test. The mean distance between renal surfaces was significantly narrower in the sliding-loop technique than in the conventional technique (1.80 ± 1.08 mm vs 5.28 ± 2.46 mm, P < .001). CONCLUSION: In the porcine model, the sliding-loop technique more effectively closed the partial nephrectomy defects compared with the conventional sliding-clip technique.

Low testosterone level is an independent risk factor for high-grade prostate cancer detection at biopsy.

OBJECTIVE: To investigate the relationship between low testosterone levels and prostate cancer detection risk in a biopsy population. PATIENTS AND METHODS: In all, 681 men who underwent initial 12-core transrectal prostate biopsy at our institution were included in this retrospective study. Patients were divided into groups with low (<300 ng/dL) and normal testosterone levels (≥300 ng/dL). Clinical and pathological data were analysed. RESULTS: Among 681 men, 86 men (12.6%) had low testosterone levels, 143 (32.7%) had a positive biopsy, and 99 (14.5%) had high-grade prostate cancer. The mean age, prostate-specific antigen (PSA) level, PSA density, body mass index (BMI), number of abnormal digital rectal examination (DRE) findings, and diabetes mellitus (DM) history were significantly different between the low and normal level testosterone groups. A low testosterone level was significantly associated with a higher risk of detection of overall prostate cancer than a normal testosterone level in univariate analysis (odds ratio [OR] 2.545, P = 0.001), but not in multivariate analysis adjusting for parameters such as age, PSA, prostate volume, BMI, abnormal DRE findings and DM (OR 1.583, P = 0.277). Meanwhile, a low testosterone level was significantly related to a higher rate of high-grade prostate cancer compared with a normal testosterone level in univariate (OR 3.324, P < 0.001) and multivariate analysis adjusting for other parameters (OR 2.138, P = 0.035). CONCLUSION: Low testosterone level is an independent risk factor for high-grade prostate cancer detection at biopsy. Therefore, checking testosterone levels could help to determine whether prostate biopsy should be carried out.

Numerical analysis of the urine flow in a stented ureter with no peristalsis.

A ureteral stenosis or occlusion causes the disturbance of normal urine flow and results in renal failure. Ureteral stents are used to relieve the stagnation of urine in the upper urinary tract. Peristalsis in the ureter, which occurs to help urine flow, becomes to weaken when a stent is inserted and effective peristalsis disappears as time goes on, and a stented ureter seems to be tubular and curved in the human body. Double J stents, which are manufactured by many medical companies and are used widely these days, have different geometries of side holes in the stent shafts. In total, 12 models-six curved models of a stented ureter according to different numbers and positions of side holes and ureteral and stent stenoses and another six straight models for comparison with the curved ones-were made based on the data collected from 19 men. The flow rate and pattern in the stented ureter were evaluated using computational fluid dynamics (CFD). According to the results, curved models reflecting the human anatomy seem to be more desirable in the CFD simulation of urine flow and must be good for evaluating the effect of geometrical variations in stent design on urine flow.

Numerical analysis of the effect of side holes of a double J stent on flow rate and pattern.

A double J stent has been used widely these days for patients with a ureteral stenosis or with renal stones and lithotripsy. The stent has multiple side holes in the shaft, which supply detours for urine flow. Even though medical companies produce various forms of double J stents that have different numbers and positions of side holes in the stent, the function of side holes in fluid dynamics has not been studied well. Here, the flow rate and pattern around the side holes of a double J stent were evaluated in curved models of a stented ureter based on the human anatomy and straight models for comparison. The total flow rate was higher in the stent with a greater number of side holes. The inflow and outflow to the stent through the side holes in the curved ureter was more active than in the straight ureter, which means the flow through side holes exists even in the ureter without ureteral stenosis or occlusion and even in the straight ureter. When the diameter of the ureter changed, the in-stent flow rate in the ureter did not change and the extraluminal flow rate was higher in the ureter with a greater diameter.

Mini-percutaneous Nephrolithotomy vs Retrograde Intrarenal Surgery for Renal Stones Larger Than 10 mm: A Prospective Randomized Controlled Trial.

OBJECTIVE: To compare miniaturized percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS) in the management of renal stones >10 mm in a single session. METHODS: Seventy patients presenting with renal stones >10 mm were randomized to a mini-PCNL or an RIRS group in a ratio of 1:1. Randomization was performed by a biostatistician and opened to the surgeon at the time of the patient's admission on the day before surgery. Patient and stone characteristics, perioperative outcomes, and complications were compared between the 2 groups. The primary end point of "stone-free" which was defined as no residual stone or stones <2 mm on computed tomography within 3 months postoperatively. RESULTS: Thirty-five patients (mini-PCNL) and 33 (RIRS) were included in the final analysis. Mini-PCNL and RIRS had a stone-free rate of 85.7% and 97.0%, respectively (P = .199). Operation time (P = .148), hemoglobin decline (P = .323), and hospital stay (P = .728) were similar between the 2 groups. Pain visual analog score at 1 hour postoperatively (P = .029) and analgesic requirement (P = .050) were higher in the RIRS group. Two patients in the mini-PCNL group and 1 in the RIRS group had minor pelvic or ureter perforation. One patient in each of the 2 groups had hypertension and urinary tract infection. CONCLUSION: Mini-PCNL and RIRS are safe and feasible surgical options to manage renal stones >10 mm. RIRS produced a slightly higher stone-free rate, but more immediate postoperative pain and higher analgesic requirement compared with mini-PCNL.