Clinical management of nonobstructive azoospermia: An update.

Approximately 1% of the general male population has azoospermia, and nonobstructive azoospermia accounts for the majority of cases. The causes vary widely, including chromosomal and genetic abnormalities, varicocele, drug-induced causes, and gonadotropin deficiency; however, the cause is often unknown. In azoospermia caused by hypogonadotropic hypogonadism, gonadotropin replacement therapy can be expected to produce sperm in the ejaculate. In some cases, upfront varicocelectomy for nonobstructive azoospermia with varicocele may result in the appearance of ejaculated spermatozoa; however, the appropriate indication should be selected. Each guideline recommends microdissection testicular sperm extraction for nonobstructive azoospermia in terms of successful sperm retrieval and avoidance of complications. Sperm retrieval rates generally ranged from 20% to 70% but vary depending on the causative disease. Various attempts have been made to predict sperm retrieval and improve sperm retrieval rates; however, the evidence is insufficient. Further evidence accumulation is needed for salvage treatment in cases of failed sperm retrieval. In Japan, there is inadequate provision on the right to know the origin of children born from artificial insemination of donated sperm and the rights of sperm donors, as well as information on unrelated family members, and the development of these systems is challenging. In the future, it is hoped that the pathogenesis of nonobstructive azoospermia with an unknown cause will be elucidated and that technology for omics technologies, human spermatogenesis using pluripotent cells, and organ culture methods will be developed.

Enfortumab vedotin prolongs overall survival in metastatic urothelial carcinoma following pembrolizumab therapy in real-world data.

OBJECTIVE: In December 2021, enfortumab vedotin (EV), an antibody-drug conjugate directed against nectin-4, was approved in Japan as a new treatment after platinum-containing chemotherapy and PD-1/PD-L1 inhibitors. This study evaluated, using real-world data, the efficacy and safety of EV therapy in patients with metastatic urothelial carcinoma (mUC). MATERIALS AND METHODS: Fifty-five patients with mUC who discontinued pembrolizumab therapy due to disease progression between June 2018 and April 2023 at Yokohama City University Hospital were evaluated retrospectively. Of the 55 patients, 25 received EV therapy (EV group) and 30 did not (non-EV group). All patients who underwent EV therapy were diagnosed with disease progression after the approval of EV in Japan. RESULTS: The median (range) follow-up period after pembrolizumab discontinuation was 6.3 (0.7-31.1) months. There were eight (32.0%) deaths due to cancer in the EV group and 27 (90.0%) in the non-EV group. The overall survival (OS) after pembrolizumab discontinuation was not reached in the EV group versus 2.6 months in the non-EV group (p < 0.001). A multivariate analysis revealed that EV therapy (EV vs. non-EV group; hazard ratio 0.26; 95% confidence interval 0.16-0.41; p < 0.001) was an independent prognostic factor for OS. CONCLUSION: EV prolonged OS in mUC following pembrolizumab therapy in real-world data.

Effect of a web-based fertility preservation training program for medical professionals in Japan.

BACKGROUND: Our web-based training program called "Educating Medical Professionals about Reproductive Issues in Cancer Healthcare" aims to help healthcare professionals communicate promptly with patients and survivors who are adolescents and young adults, with information pertinent to reproductive health issues such as the risk of infertility and fertility preservation. METHODS: The study participants were professional healthcare providers, including physicians, nurses, pharmacists, social workers, midwives, psychologists, laboratory technicians, genetic counselors, and dieticians. Pre- and post- and 3-month follow-up tests consisting of 41 questions were administered to measure changes in knowledge and confidence. The participants also received a follow-up survey that covered confidence, communication techniques, and practice habits. A total of 820 healthcare providers participated in this program. RESULTS: The mean total score from the pre-test to the post-test grew significantly (p < 0.01), and participants' self-confidence increased. In addition, there was a change in the behavior of healthcare providers, who began asking about patients' marital status and parity. CONCLUSION: Our web-based fertility preservation training program improved knowledge and self-confidence regarding fertility preservation issues among healthcare providers caring for adolescents and young adult cancer patients and survivors.

Patient-specific simulations and navigation systems for partial nephrectomy.

Partial nephrectomy (PN) is the standard treatment for T1 renal cell carcinoma. PN is affected more by surgical variations and requires greater surgical experience than radical nephrectomy. Patient-specific simulations and navigation systems may help to reduce the surgical experience required for PN. Recent advances in three-dimensional (3D) virtual reality (VR) imaging and 3D printing technology have allowed accurate patient-specific simulations and navigation systems. We reviewed previous studies about patient-specific simulations and navigation systems for PN. Recently, image reconstruction technology has developed, and commercial software that converts two-dimensional images into 3D images has become available. Many urologists are now able to view 3DVR images when preparing for PN. Surgical simulations based on 3DVR images can change surgical plans and improve surgical outcomes, and are useful during patient consultations. Patient-specific simulators that are capable of simulating surgical procedures, the gold-standard form of patient-specific simulations, have also been reported. Besides VR, 3D printing is also useful for understanding patient-specific information. Some studies have reported simulation and navigation systems for PN based on solid 3D models. Patient-specific simulations are a form of preoperative preparation, whereas patient-specific navigation is used intraoperatively. Navigation-assisted PN procedures using 3DVR images have become increasingly common, especially in robotic surgery. Some studies found that these systems produced improvements in surgical outcomes. Once its accuracy has been confirmed, it is hoped that this technology will spread further and become more generalized.

Predictive factors for pentafecta achievement in robot-assisted partial nephrectomy for intermediate highly complex RENAL tumors (RENAL score ≥ 7).

OBJECTIVES: To investigate the predictive factors for pentafecta achievement of robot-assisted partial nephrectomy (RAPN) for intermediate highly complex renal tumors (RENAL score ≥ 7). METHODS: We retrospectively analyzed the data of 247 patients with renal tumors with a RENAL score ≥ 7 who underwent RAPN. Baseline characteristics and perioperative outcomes were compared between the pentafecta achieved group and the unachieved group. A multivariable logistic regression model was used to identify the predictive factors for pentafecta achievement for cT1 renal tumors with a RENAL score ≥ 7. RESULTS: Of the 247 patients, 75 (30.3%) patients were in the achieved group and 172 (69.7%) patients were in the unachieved group. The median warm ischemia time and total operation time were 18 min versus 23 min (p < 0.001) and 179 min versus 201 min (p < 0.001) in the achieved and unachieved groups, respectively. In the unachieved group, six patients (3.4%) had major perioperative complications (Clavien-Dindo classification system ≥3). The median preservation rates of estimated GFR at the 1-year postoperative period were 96.5% versus 83.0% (p < 0.001) in the achieved and unachieved groups. Multivariable logistic regression models revealed that age and tumor size were independent predictive factors for pentafecta achievement for cT1 renal tumors with a RENAL score ≥ 7. There were no significant differences in cancer-free survival between the two groups (p = 0.456). CONCLUSION: Age and tumor size were independent predictive factors for pentafecta achievement, although there was no difference in oncological outcomes between the pentafecta achieved group and the unachieved group in RAPN for cT1 renal tumors with a RENAL score ≥ 7.

Monozygotic adult twins with nonmosaic Klinefelter syndrome with different results of sperm retrieval.

Klinefelter syndrome and monozygotic twins are both rare. The reports of monozygotic twins with Klinefelter syndrome to have undergone fertility treatment are uncommon. This case report describes a case of 30-year-old monozygotic adult twin brothers diagnosed with nonmosaic Klinefelter syndrome following the complaint of infertility. The result of semen analysis showed cryptozoospermia (very low sperm count) and azoospermia (zero sperm count) with physical findings and lifestyles being very similar. They both underwent microtesticular sperm extraction. One had successful sperm retrieval and achieved pregnancy through intracytoplasmic sperm injection, whereas the other did not. Testicular pathological findings showed Sertoli cell-only syndrome. To the best of our knowledge, this is the first report on monozygotic adult twins both of whom underwent microtesticular sperm extraction and resulted in different outcomes.

Effect of keishibukuryogan combined with tocopherol nicotinate on sperm parameters in patients with a varicocele.

OBJECTIVE: To evaluate the efficacy of keishibukuryogan, a traditional Kampo formula known to be an anti-Oketsu (impaired microcirculation and non-physiological blood congestion) drug, in combination with an anti-oxidant for the treatment of varicoceles. METHODS: We retrospectively analyzed 119 patients with palpable and subclinical varicoceles who were treated with 7.5 g/day of keishibukuryogan and 600 mg/day of tocopherol nicotinate. Their motile sperm concentrations at the start of medication and after 3 months were compared. As a subgroup analysis, a comparison test was carried out between patients with a high-grade varicocele and those with a low-grade varicocele. RESULTS: The mean age of the study patients was 35.6 years. Among them, 17, 41, 44 and 17 had subclinical, grade 1, grade 2 and grade 3 varicoceles, respectively. Overall, the differences in motile sperm concentration (millions/mL) before and after treatment were not significant (median 0.58, 95% confidence interval -0.12 to 1.56; P = 0.115). The results of the subgroup analysis showed that the motile sperm concentration in patients with a low-grade varicocele significantly increased (median 1.21, 95% confidence interval 0.45-2.47; P = 0.024); however, no significant improvements were seen in patients with a high-grade varicocele. CONCLUSIONS: The results of the present study showed that the combination of keishibukuryogan and an anti-oxidant had a limited effect on varicoceles, but they suggest that it is effective for the treatment of low-grade varicoceles.

Fertility and sexual dysfunction in young male cancer survivors.

Background: Newly emerging serious post-treatment complications among young male cancer survivors involve fertility and sexual function, preventing them from pursuing a normal family life. Methods: We studied and summarized published studies that assess the relationship between cancer treatments and reduced spermatogenesis or sexual dysfunction. Main findings: Infertility often occurs because of anticancer therapies that impair spermatogenesis. While some patients postremission functionally recover fertility, others experience a decreased sperm count and azoospermia. Fertility-preserving modalities are currently being promoted worldwide to preserve spermatogenesis following cancer therapy. Patients who can ejaculate and have sperm in their semen should cryopreserve semen. However, for patients who have never ejaculated before puberty or in whom spermatogenesis has not been established, testis biopsy is performed to collect and preserve sperm or germ cells. Fertility preservation is gaining popularity and requires continuous information dissemination to oncologists and cancer treatment professionals. Furthermore, male sexual dysfunction predominantly involves erectile dysfunction and ejaculation disorder. Conclusion: Although preventive and therapeutic methods for these disorders have been established within urology, patients and medical professionals in other fields remain uninformed of these advances. Therefore, dissemination of information regarding fertility preservation techniques should be accelerated.

Antioxidant vitamins and lysophospholipids are critical for inducing mouse spermatogenesis under organ culture conditions.

In vitro mouse spermatogenesis using a classical organ culture method became possible by supplementing basal culture medium with only the product of bovine serum albumin purified by chromatography (AlbuMAX), which indicated that AlbuMAX contained every chemical factor necessary for mouse spermatogenesis. However, since the identity of these factors was unclear, improvements in culture media and our understanding of the nutritional and signal substances required for spermatogenesis were hindered. In the present study, chemically defined media (CDM) without AlbuMAX was used to evaluate each supplementary factor and their combinations for the induction of spermatogenesis. Similar to in vivo conditions, retinoic acid, triiodothyronine (T3 ), and testosterone (T) were needed. Based on differences in spermatogenic competence between AlbuMAX, fetal bovine serum, and adult bovine serum, we identified α-tocopherol, which strongly promoted spermatogenesis when combined with ascorbic acid and glutathione. Differences were also observed in the abilities of lipids extracted from AlbuMAX using two different methods to induce spermatogenesis. This led to the identification of lysophospholipids, particularly lysophosphatidylcholine, lysophosphatidic acid, and lysophosphatidylserine, as important molecules for spermatogenesis. New CDM formulated based on these results induced and promoted spermatogenesis as efficiently as AlbuMAX-containing medium. In vitro spermatogenesis with CDM may provide a unique experimental system for research on spermatogenesis that cannot be performed in in vivo experiments.

Gap between UAS and ureteroscope predicts renal stone-free rate after flexible ureteroscopy with the fragmentation technique.

PURPOSE: To assess the effect of our new classification on surgical outcomes after flexible ureteroscopy (fURS) for kidney stones. METHODS: We retrospectively examined 128 patients after single renal fURS procedures performed using ureteral access sheaths (UASs) with the fragmentation technique. Based on the gap (calculated by subtracting the ureteroscope diameter from the UAS diameter), enrolled patients were divided into three groups: small (< 0.6 mm), medium (0.6 to < 1.2 mm), and large space groups (≥ 1.2 mm). Stone-free (SF) status was defined as either complete absence of stones (SF) or the presence of stones < 4 mm in diameter on non-contrast computed tomography (NCCT). RESULTS: The SF rate was significantly lower in the small space group (50% in small, 97.9% in medium, 89.2% in large; p = 0.001). Perioperative complications over Clavien-Dindo Grade I were observed in 16.7%, 4.2%, and 8.1% of patients, respectively (p = 0.452). The ratio of stone volume and operative time (efficiency of stone removal) was significantly higher in the large space group compared to the small and medium space groups (0.009 ± 0.003 ml/min, 0.013 ± 0.005 ml/min, 0.027 ± 0.012 ml/min, respectively; p < 0.001). CONCLUSION: Our findings that gaps > 0.6 mm (1.8 Fr), including the combination of a 9.5-Fr UAS and a small caliber ureteroscope, improve SF rates, and larger gaps facilitate stone removal efficiency providing the basis for future development of clinical protocols aimed at improving outcomes.

Fertility preservation immediately after therapeutic abortion results in multiple normal follicular growth with the absence of mature oocytes due to early luteinization: a case report and literature review.

Cancer therapy has priority over fertility preservation. The time available for fertility preservation in patients with cancer is often very limited and depends on the condition of the underlying disease. This case report presents the results of two rounds of controlled ovarian stimulations (COSs) performed after an induced abortion. The patient had mixed phenotype acute leukemia diagnosed during early pregnancy and underwent a surgical abortion, followed by ovarian stimulation using urinary follicle-stimulating hormone (uFSH) and gonadotropin-releasing hormone (GnRH) agonists. Oocyte retrieval was subsequently performed for oocyte cryopreservation. Despite good hormonal and ultrasonic follicular growth, no oocytes were obtained. During a second COS performed at a low human chorionic gonadotropin (hCG) level (less than 100 IU/L), several mature oocytes were obtained, suggesting that higher hCG levels during COS induce the absence of mature oocytes during normal follicular growth. It is recommended to start COS post-abortion after confirming a low hCG level while considering the timing of cancer treatment.

Development and internal validation of a nomogram to predict perioperative complications after flexible ureteroscopy for renal stones in overnight ureteral catheterization cases.

PURPOSE: To identify risk factors by developing and internally validating a nomogram for preventing perioperative complications in overnight ureteral catheterization cases after fURS for kidney stones. METHODS: We retrospectively examined 309 patients with overnight ureteral catheterization after single fURS procedures for renal stones. fURS procedures were performed based on the fragmentation technique. The ureteral catheter was removed on postoperative day 1. Within this group, patients who experienced perioperative complications (complication group) were compared with those who did not experience complications (non-complication group). The complication group included 77 patients whose Clavien-Dindo classification score was I, II, III, or IV and/or those whose body temperature during hospitalization was over 37.5 °C. RESULTS: The overall stone volume, stone-free rate, incidence of perioperative complications, and procedure duration were 1.39 mL, 94.8%, 24.9%, and 62 min, respectively. Severe complications of a Clavien-Dindo level III or IV were observed in only four cases (1.3%). Multivariate assessment revealed five independent predictors of perioperative complications after fURS with overnight catheterization: age (p = 0.11), sex (p = 0.067), stone volume (p = 0.33), Hounsfield units (p = 0.16), and narrow ureter (p = 0.018). We developed a nomogram to predict perioperative complications after fURS using these parameters. CONCLUSIONS: We developed a predictive model for perioperative complications of patients with overnight catheterization after fURS for renal stones. This model could select patients who were at a low risk of complications.

In vitro spermatogenesis in two-dimensionally spread mouse testis tissues.

PURPOSE: Mouse in vitro spermatogenesis is possible with classical organ culture methods, by placing the testis tissue at the interphase between culture medium and air. In this condition, however, a tissue piece tends to round up to be compact, whose central region suffers from shortage of nutrients and oxygen. In this study, the authors improved the culture condition by spreading each tissue thin and flat, by which they were able to get better access to the oxygen and nutrients. METHODS: Immature mouse testis tissues placed on agarose gel block were forced to spread flat by covering with a polydimethylsiloxane (PDMS) ceiling chip (PC chip). They were then cultured for weeks and evaluated by the transgene expression of Acr-Gfp, which reflects the progression of spermatogenesis. RESULTS: Testis tissues covered with PC chip initiated and maintained spermatogenesis in its wider region than those without PC chip covering. Flow cytometric analysis demonstrated that the PC method yielded more numerous meiotic germ cells than those without PC. Immunohistochemical examination confirmed the authentic histological figure of spermatogenesis from spermatogonia up to round or elongating spermatids. CONCLUSIONS: The PC chip method is simple and effective to improve the efficiency of in vitro spermatogenesis in the organ culture system.

A monolayer microfluidic device supporting mouse spermatogenesis with improved visibility.

In our previous study, we produced a microfluidic device (MFD) which successfully maintained spermatogenesis for over 6 months in mouse testis tissues loaded in the device. In the present study, we developed a new MFD, a monolayer device (ML-D) with a barrier structure consisting of pillars and slits, which is simpler in design and easier to make. This ML-D was also effective for inducing mouse spermatogenesis and maintained it for a longer period than the conventional culture method. In addition, we devised a way of introducing sample tissue into the device during its production, just before bonding the upper layer of polydimethylsiloxane (PDMS) and bottom glass slide. The tissue can obtain nutrients horizontally from the medium running beside it and oxygen vertically from above through PDMS. In addition, the glass slide set at the bottom improved the visibility of the sample tissue with an inverted microscope. When we took photos of cultured tissue of the Acr-Gfp transgenic mouse testis in ML-D sequentially every day, morphological changes of the acrosome during spermiogenesis were successfully recorded. The ML-D is simple in design and useful for culturing testis tissue for inducing and maintaining spermatogenesis with clearer visibility. Due to the new method of sample loading, tissues other than testis should also be applicable.

Neonatal testis growth recreated in vitro by two-dimensional organ spreading.

Organ culture experiments can be hampered by central degeneration or necrosis due to the inadequate permeation of oxygen and nutrients, which deteriorates the function and growth of cultured tissues. In the current study, we aimed to overcome this limitation of organ culture through spreading the tissue two dimensionally on an agarose gel stand and molding into a disc shape by placing a ceiling of polydimethylsiloxane (PDMS) chip, which is highly oxygen permeable. By this, every part of the tissue can receive a sufficient supply of oxygen through PDMS as well as nutrients through the agarose gel below. This method not only prevented central necrosis of tissues, but also supported the tissue growth over time. In addition, such growth, as volume enlargement, could be easily measured. Under these conditions, we examined the effect of several factors on the growth of neonatal mouse testis, and found that follicle stimulating hormone (FSH) and insulin significantly promoted the growth. These results are in good agreement with previous in vivo reports. Notably, the growth achieved over 7 days in our in vitro system is almost comparable to, about 80% of, that observed in vivo. Thus, we successfully monitored the promotion of tissue growth beyond the limits of the conventional organ culture method. This extremely simple method could offer a unique platform to evaluate the growth as well as functional properties of organs, not only the testis but also others as well.

Outcome of flexible ureteroscopy for renal stone with overnight ureteral catheterization: a propensity score-matching analysis.

PURPOSE: To evaluate the influence of overnight ureteral catheterization and determine if routine long-term post-stenting can be avoided in flexible ureterorenoscopy (fURS) procedure for kidney stone. METHODS: Three hundred ninety-three patients who underwent single fURS for kidney stone between January 2013 and June 2016 at a single institute were retrospectively analyzed. The stone-free (SF) and perioperative complication rates in patients with routine long-term post-stenting after fURS (long-term stent group) were compared with those of patients with overnight ureteral catheterization (short-term stent group). Propensity score-matching analysis was used to adjust the difference in baseline preoperative parameters between the two groups. All preoperative parameters were chosen to develop the propensity score, and 74 patients in the short-term stent group were retrospectively matched with the patients in the long-term stent group at a 1:1 ratio. RESULTS: Patient characteristics included age, sex, side of involvement, height, body weight, body mass index, number of stone(s), stone volume, Hounsfield units of stone, preoperative white blood cell count, preoperative C-reactive protein, preoperative creatinine, pretreatment, pre-stenting, stenosis of the ureter, and procedure duration. The SF rates were 91.9 and 93.2% in the short-term and long-term stent groups, respectively. Perioperative complications were 14.9 and 12.2%. No difference was noted between the two groups in terms of SF and perioperative complication rates. CONCLUSIONS: Short-term post-stenting using overnight ureteral catheterization in uncomplicated cases after fURS for kidney stone was as effective as conventional long-term post-stenting in reducing postoperative complications. These preliminary data suggest the possibility that routine long-term post-stenting was unnecessary.

In vitro spermatogenesis: A century-long research journey, still half way around.

BACKGROUND: Spermatogenesis is one of the most complicated cellular differentiation processes in a body. Researchers struggled to find and develop a micro-environmental condition that can support the process in vitro. Such endeavors can be traced back to a century ago and are yet continuing. METHODS: Reports on in vitro spermatogenesis and related works were selected and classified into four categories based on the method used; organ culture, tubule culture, cell culture, and 3-dimensional cell culture methods. Each report was critically reviewed from the present point of view by authors who have been working on in vitro spermatogenesis with organ culture method over a decade. RESULTS: The organ culture method has the longest history and is the most successful method, which produced fertile mouse sperm from spermatogonial stem cells. Formulation of the medium was a key factor, most importantly serum-derived substances. However, factors in the serum that induce and support spermatogenesis in the cultured tissue remain to be identified. In addition, the success of mouse spermatogenesis is yet to be applied to other animals. On looking into the history of cell culture method, it became clear that Sertoli cells as feeder cells play an important role. Even with Sertoli cells, however, spermatogenic development has been limited to small parts of spermatogenesis, a segmented period of meiotic prophase for instance. Recent developments of organoid or 3-dimensional culture techniques are promising but they still need further refinements. CONCLUSION: The study of in vitro spermatogenesis progressed significantly over the last century. We need more work, however, to establish a culture system that can induce and maintain complete spermatogenesis of many if not all mammalian species.

[A Case of Endoscopic Combined Intrarenal Surgery for Multiple Encrusted Stones on a Forgotten Ureteral Stent Left for 4 Years].

A 43-year-old man underwent extracorporeal shock wave lithotripsy (ESWL) for a left ureteral stone and implantation of a loop stent for the treatment of stone pain in February 2011. However, he was lost to follow-up before the complete removal of the stones and stent. He presented to our hospital with left back pain in March 2015. An abdominal radiograph and a noncontrast computed tomography showed extensive stone formation throughout the stent. A single cystolithotripsy and a double endoscopic combined intrarenal surgery (ECIRS)were performed. All the stones and the encrusted ureteral stent were successfully removed.

Testis tissue explantation cures spermatogenic failure in c-Kit ligand mutant mice.

Male infertility is most commonly caused by spermatogenic defects or insufficiencies, the majority of which are as yet cureless. Recently, we succeeded in cultivating mouse testicular tissues for producing fertile sperm from spermatogonial stem cells. Here, we show that one of the most severe types of spermatogenic defect mutant can be treated by the culture method without any genetic manipulations. The Sl/Sl(d) mouse is used as a model of such male infertility. The testis of the Sl/Sl(d) mouse has only primitive spermatogonia as germ cells, lacking any sign of spermatogenesis owing to mutations of the c-kit ligand (KITL) gene that cause the loss of membrane-bound-type KITL from the surface of Sertoli cells. To compensate for the deficit, we cultured testis tissues of Sl/Sl(d) mice with a medium containing recombinant KITL and found that it induced the differentiation of spermatogonia up to the end of meiosis. We further discovered that colony stimulating factor-1 (CSF-1) enhances the effect of KITL and promotes spermatogenesis up to the production of sperm. Microinsemination of haploid cells resulted in delivery of healthy offspring. This study demonstrated that spermatogenic impairments can be treated in vitro with the supplementation of certain factors or substances that are insufficient in the original testes.

Ureteral stone volume and female gender predicts perioperative complications after complete ipsilateral upper urinary tract stone removal using flexible ureterorenoscopy.

PURPOSE: To identify the risk factors for perioperative complications to prevent perioperative complications after complete ipsilateral upper urinary stone removal using flexible ureterorenoscopy. MATERIALS AND METHODS: We retrospectively examined 111 patients who underwent flexible ureterorenoscopy for ipsilateral renal stones with a diameter ≥ 5 mm at the same time as ureterorenoscopy for ureteric stones. The flexible ureterorenoscopy procedures were performed following the fragmentation technique. Patients who experienced (complication group) and did not experience (non-complication group) perioperative complications were compared. The complication group included 33 patients with Clavien-Dindo classification scores of I, II, III, or IV and/or those with a body temperature of > 37.5 â„ƒ during hospitalization. RESULTS: The overall stone volume, stone-free rate and procedure duration were 1.71 mL, 96.4% and 77 min, respectively. The rate of perioperative complications was 29.7% (grade 1, 2 and 3 was 23.4%, 5.4% and 0.9%, respectively). Severe complications (Clavien-Dindo grade 4) were not observed. Multivariable analysis revealed that ureteral stone volume and female patients were independent predictors of perioperative complications after flexible ureterorenoscopy (p = 0.015 and 0.017, respectively). CONCLUSIONS: This study showed that ureteral stone volume and female gender have the possibility to increase perioperative complications. These preliminary data help to select for patients who are at low risk of complications. Therefore, in these selected patients, complete ipsilateral upper urinary tract stone removal using flexible ureterorenoscopy may reduce the recurrence of urolithiasis without increasing perioperative complications.