Combined Percutaneous and Endoscopic Ureterolithotripsy of Calcified Double J Stent.

In urological practice, the routine procedure of placing a double J stent aims to facilitate drainage of the upper urinary system. Despite its temporary nature and the necessity for timely removal, approximately 12% of these stents are retained in patients for extended durations due to various reasons. Forgotten ureteral stents can lead to complications that increase the morbidity and mortality of patients. This report discusses a case of the double J stent that became calcified due to prolonged use and needed to be removed in a combined procedure.

Comparing efficacy and safety of mirabegron, tamsulosin, and solifenacin in ureteral stent-related symptoms: outcomes from a network meta-analysis.

Background: Although ureteral stents are a well-established and commonly used method for renal drainage, the ureteral stent-related symptoms (SRSs) they cause in patients cannot be ignored. It is currently unclear whether mirabegron has a place in the treatment of SRSs. Our study aims to systematically evaluate the efficacy and safety of mirabegron in treating SRSs in adult patients. Methods: Through a systematical search of multiple scientific databases before August 2023, we performed a systematic review and meta-analysis of the primary outcomes of interest according to the PRISMA. Analysis was performed under multivariate random-effects network models and effects of drugs was ranked with surface under the cumulative ranking curves (SUCRA) probabilities. Results: Sixteen studies involving 2,002 patients were included. All regimens (including mirabegron, solifenacin, and tamsulosin) were significantly better than placebo in urinary symptoms. Solifenacin was associated with more adverse drug events than mirabegron and tamsulosin. The SUCRA values showed that mirabegron was the best in the outcomes of body pain (71.5%), sexual matters (76.4%), and adverse events (70.5%). Solifenacin was the best in the outcomes of urinary symptoms (73.1%), general health (81.0%), and work performance (85.1%). Tamsulosin had the lowest rate of all outcomes. Conclusions: Compared with traditional drugs for relieving SRSs, mirabegron performs best in terms of alleviating body pain, sexual matters, and adverse events, with little difference in urinary symptoms and general health. Further high-quality prospective double-blinded randomized controlled trials (RCTs) are required to provide sufficient evidence supporting our observations.

Acute kidney injury after colorectal surgery with prophylactic ureteral stents.

BACKGROUND: After colorectal surgery, acute kidney injury (AKI) results from a complex interplay of multiple independent causes and preventive measures that occur during the hospitalization. Prophylactic stenting for ureter identification has been identified as a potential cause, but the evidence is conflicting, possibly because of differing baseline characteristics and procedure-related approaches. OBJECTIVE: This retrospective cohort study assesses the role of stents in the etiology of AKI after determining the independent predictors of AKI. METHODS: From a population of 1224 consecutive colorectal patients (from 8/1/2016 through 12/31/2021), 382 (31.2%) received ureteral stents, and propensity score matching was used to create stented and control groups. Emergent cases and patients with sepsis were excluded from the analysis. Previously identified independent predictors of AKI, minimally invasive procedures, and a history of diabetes mellitus were used as criteria to create two balanced groups. RESULTS: Baseline demographic characteristics and procedure-related factors baseline factors were similar between the groups. There was no difference in the rate of AKI between stented patients and controls (P = 0.82), nor was there any difference in postoperative complications, such as chronic renal insufficiency (CRI, P = 0.49), average postoperative creatinine (P = 0.67), urinary tract infections (UTI, P = 0.82), any postoperative infection (P = 0.48), in-hospital complications (P = 1.00), length of stay (LOS, P = 0.15), and 30-day readmissions (P = 0.79). CONCLUSIONS: In a population of patients where stenting was frequently employed, ureter stents placed for identification did not appear to cause AKI or AKI-related complications.

Arterioureteral fistula and refractory fatal pseudo-aneurysm in a patient receiving kidney transplantation.

Arterioureteral fistula represents a rare yet consequential urological complication characterized by persistent and refractory urinary tract bleeding. Its emergence typically involves aneurysm formation, presenting significant life-threatening implications. Nonetheless, its infrequency contributes to sparse documentation of incidences in post-kidney transplant recipients, thereby fostering numerous uncertainties concerning associated risks. A 67-year-old male patient, afflicted with end-stage renal failure and a history of urinary tract infection, underwent a living donor kidney transplant four months prior. Complications involving intraoperative bleeding necessitated the prolonged placement of a ureteral stent post-surgery. Subsequently, he experienced an abrupt onset of ureteral bleeding accompanied by shock, later diagnosed via contrast-enhanced computed tomography as pseudo-aneurysm formation in the right external iliac artery proximal to the allograft renal artery anastomosis, in conjunction with a fistula formation involving the donor ureter. Despite repeated attempts at intervention with covered stenting, the aneurysm persisted and proved refractory to resolution. Tragically, seven months later, the aneurysm ruptured, culminating in the demise of the patient. Our report details a case involving perioperative complications following kidney transplantation, persistent bacteriuria, and prolonged ureteral stenting, ultimately leading to the development of an arterioureteral fistula. Despite undergoing stent graft insertion as an intervention, the patient succumbed to aneurysm rupture associated with the arterioureteral fistula. This condition, though rare, can prove fatal following kidney transplantation. Consequently, future endeavors in this domain necessitate an emphasis on optimizing risk management, refining diagnostic approaches, and devising more effective therapeutic strategies to mitigate such complications.

MAGnetic REtriaval Device for Minimally Invasive Ureter Stent Removal.

Purpose: To assess the effectiveness and pain intensity associated with magnetic ureteral stent removal using a retriever, without the aid of ultrasound guidance. Methods: We prospectively enrolled 100 patients who underwent retrograde rigid and flexible ureterorenoscopy with or without laser lithotripsy for ureteronephrolithiasis treatment from September 2021 to June 2023. These patients were assigned in two groups. Group 1 underwent the traditional ureteral stent insertion, while Group 2 underwent magnetic ureteral stent insertion. Both insertion and removal times were documented. The indwelling time for ureteral stents was 14 days. One group underwent stent removal via flexible cystoscopy using grasping forceps and the other group using just a magnetic retriever, without the aid of ultrasound guidance. The numeric pain rating scale, recommendation rate, and a standardized self-answered ureter stent symptoms questionnaire (USSQ) were obtained directly after stent removal. Results: Both groups presented comparable characteristics in factors such as age, body mass index, history of stone treatments, procedure type, and complication rates during and post-surgery. Time taken for ureteral stent insertion did not differ significantly between the groups (131.2 seconds for Group 1 vs 159.1 seconds for Group 2). However, the stent removal time (152.1 seconds for Group 1 vs 35.4 seconds for Group 2) and pain intensity (6 for Group 1 vs 2 for Group 2) were significantly lower for Group 2. Furthermore, five out of the six sections of the USSQ showed significantly better results for Group 2. Conclusions: The use of magnetic ureteral stents, as a safe and efficient alternative to conventional ureteral stents, not only eliminates the need for cystoscopy but also conserves resources and reduces patient discomfort.

Prospective comparison of two methods for correct ureteral stent placement in pediatric laparoscopic pyeloplasty.

INTRODUCTION: Ureteral stent placement during laparoscopic pyeloplasty is a common procedure in pediatric patients. Although an apparently safe maneuver, ascending placement of the stent can lead to complex removal or repositioning reinterventions. OBJECTIVE: In this study we compare two methods for intraoperative verification of correct positioning. STUDY DESIGN: Prospective observational study collecting data on laparoscopic pyeloplasties in pediatric patients in our center over three years. We carried out descriptive and univariate comparative analyses. Data were compared between ultrasound and reflux visualized by the catheter after intraoperative salineinjection into the bladder through the urethral catheter. We recorded time to catheter visualization in both ultrasonography and in reflux from the start of bladder instillation, as well as bladder volume at the time of placement verification with each method. RESULTS: Data were collected from 20 patients (15 male and 5 female) with a median age of 48 months. Pyeloplasty was successful in 100% of the sample (as observed by ultrasound and MAG-3), while one patient had postoperative leak requiring nephrostomy placement. Correct distal positioning of the ureteral stent could be verified by intraoperative ultrasound and reflux in all cases. Using reflux, the bladder volume needed to verify correct positioning exceeded the age-related maximum in half the cohort, while on ultrasound, the stent was visualized in the bladder without reaching the maximum bladder capacity for age in any case (p = 0.02 comparing percentages). Likewise, mean time to verification was lower with ultrasound than with reflux (61.8 s versus 115 s), but without these differences reaching statistical significance (p = 0.14). DISCUSSION: The present study is the first to compare two methods to verify the correct positioning of the ureteral stent in laparoscopic pyeloplasties in pediatric patients. Our results show that both intraoperative ultrasound and visualization of reflux are useful methods, although ultrasound requires a lower volume of saline instilled through the bladder catheter for verification. This work can be very useful for the daily clinical practice of urologists and pediatric surgeons. CONCLUSIONS: Both intraoperative ultrasound and visualization of reflux are useful methods to verify the correct positioning of the ureteral stent in laparoscopic pyeloplasty of pediatric patients. With ultrasound, a smaller volume is required to check for reflux. Although ultrasound is faster for verification, there are no differences in procedural times.

Malignant peritoneal mesothelioma presenting with bilateral hydronephrosis and renal insufficiency: a case report and literature review.

Introduction: Malignant peritoneal mesothelioma (MPM) is an extremely rare tumor with nonspecific clinical manifestations, making diagnosis challenging. Case presentation: Herein, we report a case of MPM with occult onset presenting with bilateral hydronephrosis and renal insufficiency. A 30-year-old man was admitted to the Urology Department because of recurrent bilateral lower back pain. The etiology was unclear after a series of laboratory tests, imaging examinations, bone marrow aspiration, renal puncture biopsy, ascites examination, ureteroscopy, and so on. Finally, MPM was diagnosed by laparoscopic exploration and biopsy. Moreover, during the course of the disease, the patient's bilateral ureters were compressed, and the obstruction could not be relieved after the placement of ordinary ureteral stents. Percutaneous nephrostomy or metal ureteral stenosis was appropriate in managing malignant ureteral obstruction as it could improve renal function. Conclusions: The onset of this case was insidious, and the diagnosis was difficult, with a poor prognosis. To date, only a handful of cases have been reported. We hope this case can provide some enlightenment for our clinical work.

Disposable grasper-integrated flexible cystoscope for ureteral stent removal in transplanted patients; focus on feasibility, safety, and patient experience. Results and micro-cost analysis from a tertiary referral center.

INTRODUCTION & OBJECTIVES: To evaluate ureteral stent removal (SR) using a grasper-integrated disposable flexible cystoscope (giFC-Isiris ®, Coloplast ®) after kidney transplantation (KT), with a focus on feasibility, safety, patient experience, and costs. MATERIAL AND METHODS: All consecutive KT undergoing SR through giFC were prospectively enrolled from January 2020 to June 2023. Patient characteristics, KT and SR details, urine culture results, antimicrobial prescriptions, and the incidence of urinary tract infections (UTI) within 1 month were recorded. A micro-cost analysis was conducted, making a comparison with the costs of SR with a reusable FC and grasper. RESULTS: A total of 136 KT patients were enrolled, including both single and double KT, with 148 stents removed in total. The median indwelling time was 34 days [26, 47]. SR was successfully performed in all cases. The median preparation and procedure times were 4 min [3,5]. and 45 s[30, 60], respectively. The median Visual Analog Scale (VAS) score was 3 [1, 5], and 98.2% of patients expressed willingness to undergo the procedure again. Only one episode of UTI involving the graft (0.7%) was recorded. Overall, the estimated cost per SR procedure with Isiris ® and the reusable FC was 289.2€ and 151,4€, respectively. CONCLUSIONS: This prospective series evaluated the use of Isiris ® for SR in a cohort of KT patients, demonstrating feasibility and high tolerance. The UTI incidence was 0.7% within 1 month. Based on the micro-cost analysis, estimated cost per procedure favored the reusable FC.

Ureteral stents: What your eyes can't see! An in vitro study.

OBJECTIVES: To characterize and compare in vitro the surfaces of ureteral stents (STENTS) before utilization. METHODS: Our in vitro experiment included six unused STENTS models: three double-pigtail with side orifices (ImaJin and Stenostent [Coloplast©,France], TriaSoft [BostonScientific©,USA]), two double-pigtail without side orifice (Vortek-TumorStent [Coloplast©,France], Urosoft-TumorStent [Bard-Angiomed©,Germany]) and one single-pigtail (J-Fil [Rocamed©,Monaco]). STENTS were made of polyurethane except for ImaJin (silicone). For all STENTS, four parts of the stent were specifically analyzed under high-resolution scanning electron microscopy (HR-SEM,FEI-XL40 [Philips©,France]): surface core, lateral orifice, ureteral loop, and black marking surface. Each experiment was repeated with three different samples from three different stents. STENTS analysis included multiple imperfection searches, defined as irregularities>10µm. RESULTS: All STENTS presented imperfections with no discernible differences. Imperfections were mainly located on the stent loop and on the lateral orifice. For STENTS without side orifice (J-Fil, Urosoft) imperfections were also reported, on the beveled cut as well as the distal loop orifice. Marking surfaces examinations found defects in the Urosoft and imperfections in the ImaJin and Stenostent. The Triasoft presented a better smoothness on marking surfaces compared to other STENTS. Additional matter was reported on the loop distal orifice for J-Fil and ImaJin but all STENTS presented irregular cross-sectional aeras. CONCLUSION: All ureteral stents are not perfectly smooth even before utilization. Imperfections were noticed regardless to stent composition or shape, and could play a role in the incrustation phenomenon, is association with inner irregularities, infection, and urine composition. Both manufacturing and material could have an impact on the stent external surface's smoothness.

Percutaneous nephrostomy versus ureteral stent in hydronephrosis secondary to obstructive urolithiasis: A systematic review and meta-analysis.

Objective: To assess if there is a preferable intervention between retrograde ureteral stent (RUS) and percutaneous nephrostomy (PCN) tube, in cases of upper urinary tract stone obstruction with complications requiring urgent drainage, by evaluating outcomes regarding urinary symptoms, quality of life (QoL), spontaneous stone passage, and length of hospital stays, since there is no literature stating the superiority of one modality over the other. Methods: We searched MEDLINE and other sources for relevant articles in June 2019 without any date restrictions or filters applied. The selection was done first by the title and abstract screening and then by full-text assessment for eligibility. Only randomized controlled trials or cohort studies in patients with hydronephrosis secondary to obstructive urolithiasis that presented comparative data between PCN and RUS placement concerning at least one of the defined outcome measures were included. Lastly, MEDLINE database and PubMed platform were screened again using the same terms, from June 2019 until November 2022. Results: Of 556 initial articles, seven were included in this review. Most works were considered of moderate-to-high quality. Three studies regarding QoL showed a tendency against stenting, even though only one demonstrated statistically significant negative impact on overall health state. Two works reported significantly more post-intervention urinary symptoms in stenting patients. One article found that PCN is a significant predictor of spontaneous stone passage, when adjusted for stone size and location. Findings on length of hospital stays were not consistent among articles. Conclusion: PCN appears to be the intervention better tolerated, with less impact on the patient's perceived QoL and less post-operative urinary symptoms, in comparison with RUS. Nevertheless, further studies with larger samples and a randomized controlled design are suggested.

Recent developments in ureteral stent: Substrate material, coating polymer and technology, therapeutic function.

The ureteral stent is an effective treatment for clinical ureteral stricture following urological surgery, and the functional coating of the stent could effectively inhibit bacterial colonization and other complications. The present review provides an analysis and description of the materials used in ureteral stents and their coatings. Emphasis is placed on the technological advancements of functional coatings, taking into consideration the characteristics of these materials and the properties of their active substances. Furthermore, recent advances in enhancing the therapeutic efficacy of functional coatings are also reviewed. It is anticipated that this article will serve as a valuable reference providing insights for future research development on new drug-loaded ureteral stents.

Cesarean hysterectomy for placenta accreta spectrum: Surgeon specialty-specific assessment.

OBJECTIVE: To assess (i) clinical and pregnancy characteristics, (ii) patterns of surgical procedures, and (iii) surgical morbidity associated with cesarean hysterectomy for placenta accreta spectrum based on the specialty of the attending surgeon. METHODS: The Premier Healthcare Database was queried retrospectively to study patients with placenta accreta spectrum who underwent cesarean delivery and concurrent hysterectomy from 2016 to 2020. Surgical morbidity was assessed with propensity score inverse probability of treatment weighting based on surgeon specialty for hysterectomy: general obstetrician-gynecologists, maternal-fetal medicine specialists, and gynecologic oncologists. RESULTS: A total of 2240 cesarean hysterectomies were studies. The most common surgeon type was general obstetrician-gynecologist (n = 1534, 68.5%), followed by gynecologic oncologist (n = 532, 23.8%) and maternal-fetal medicine specialist (n = 174, 7.8%). Patients in the gynecologic oncologist group had the highest rate of placenta increta or percreta, followed by the maternal-fetal medicine specialist and general obstetrician-gynecologist groups (43.4%, 39.6%, and 30.6%, P < .001). In a propensity score-weighted model, measured surgical morbidity was similar across the three subspecialty groups, including hemorrhage / blood transfusion (59.4-63.7%), bladder injury (18.3-24.0%), ureteral injury (2.2-4.3%), shock (8.6-10.5%), and coagulopathy (3.3-7.4%) (all, P > .05). Among the cesarean hysterectomy performed by gynecologic oncologist, hemorrhage / transfusion rates remained substantial despite additional surgical procedures: tranexamic acid / ureteral stent (60.4%), tranexamic acid / endo-arterial procedure (76.2%), ureteral stent / endo-arterial procedure (51.6%), and all three procedures (55.4%). Tranexamic acid administration with ureteral stent placement was associated with decreased bladder injury (12.8% vs 23.8-32.2%, P < .001). CONCLUSION: These data suggest that patient characteristics and surgical procedures related to cesarean hysterectomy for placenta accreta spectrum differ based on surgeon specialty. Gynecologic oncologists appear to manage more severe forms of placenta accreta spectrum. Regardless of surgeon's specialty, surgical morbidity of cesarean hysterectomy for placenta accreta spectrum is significant.

Effect of theophylline on stent-related symptoms in patients undergoing Double-J ureteral stent insertion: a randomized controlled trial.

PURPOSE: To investigate the effect of oral theophylline on stent-related syndrome (SRS) after Double-J insertion. BACKGROUND: Double-J stent is widely using in many urological procedures. Infection, hematuria, and discomfort are some of common complication after stenting. Theophylline is a dimethylated xanthine that inhibits phosphodiesterase and blocks adenosine receptors. To relaxing effect of theophylline on smooth muscles and its effects on the urinary system, it seems it could reduce complications after inserting Double-J stent especially ureteral stent syndrome. METHOD: In this double-blind placebo-controlled randomized clinical trial, 67 patients were enrolled. Mean (SD) age of control and theophylline group was 51.8 (12.5) and 43.9 (10.4) years old, respectively. Patients were randomized into two groups of control and theophylline. All patients were stenting with silicon Double J. Theophylline group received 100 mg of theophylline, twice daily for 30 days, while control group received placebo. Stent symptoms were assessed by questionnaire and urine culture was performed before stent removal at removal day. Statistical analysis was performed using Chi-squared test and t test with P < 0.05 considered significant. Logistic regression models were fitted, crudely and adjusted for age and sex. RESULT: Of 67 eligible patients, 60 completed the study. Theophylline significantly decreased percentages of gross hematuria (P < 0.001), dysuria (P < 0.001), and urinary frequency (P < 0.001). Microscopic hematuria (P = 0.042) and chills (P = 0.042) also decreased after theophylline. CONCLUSION: Theophylline could be an effective and safe choice for reducing SRS among patients undergoing Double-J stent insertion.

Recent development and future application of biodegradable ureteral stents.

Ureteral stenting is a common clinical procedure for the treatment of upper urinary tract disorders, including conditions such as urinary tract infections, tumors, stones, and inflammation. Maintaining normal renal function by preventing and treating ureteral obstruction is the primary goal of this procedure. However, the use of ureteral stents is associated with adverse effects, including surface crusting, bacterial adhesion, and lower urinary tract symptoms (LUTS) after implantation. Recognizing the need to reduce the complications associated with permanent ureteral stent placement, there is a growing interest among both physicians and patients in the use of biodegradable ureteral stents (BUS). The evolution of stent materials and the exploration of different stent coatings have given these devices different roles tailored to different clinical needs, including anticolithic, antibacterial, antitumor, antinociceptive, and others. This review examines recent advances in BUS within the last 5 years, providing an in-depth analysis of their characteristics and performance. In addition, we present prospective insights into the future applications of BUS in clinical settings.

Surface Modification of Zn-Cu Alloy with Heparin Nanoparticles for Urinary Implant Applications.

In this work, an investigation on the Zn-Cu alloy coated with heparin was conducted in order to explore the potentiality of its application as a feasible alternative for biodegradable implants, with the specific goal of addressing the issue of encrustation in the urinary system. The stability of the nanoparticles were characterized by dynamic light scattering. Typical surface characterization such as X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to demonstrate a successful immobilization of the NPs. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in artificial urine (AU) at 37 °C. The 8 weeks in vivo degradation, encrustation resistance, hemocompatibility, and histocompatibility were investigated by means of implantation into the bladders of rats. Both in vitro and in vivo degradation tests exhibited a higher degradation rate for Zn-Cu and NPs groups when compared to pure Zn. Histological evaluations and hemocompatibility revealed that there was no tissue damage or pathological alterations caused by the degradation process. Furthermore, antiencrustation performance and urinalysis results confirmed that the modified alloy demonstrated significant encrustation inhibitory properties and bactericidal activity compared to the pure Zn control. Our findings highlight the potential of this modified alloy as an antiencrustation biodegradable ureteral stent.

Patients undergoing double J substitution with a pigtail suture stent report a significant decrease of stent-related symptoms. Results from a prospective multicenter longitudinal trial.

PURPOSE: To compare stent-related symptoms (SRS) in patients with double J (DJ) undergoing substitution with a pigtail suture stent (PSS) after ureteroscopy (URS), through the Ureteral Stent Symptom Questionnaire (USSQ). MATERIALS AND METHODS: Patients with DJ undergoing URS for stone treatment were enrolled in this prospective multicenter longitudinal study. The USSQ was submitted thrice: 2 weeks after DJ, 2 weeks after PSS and 4 weeks after PSS removal (baseline). PRIMARY ENDPOINT: to compare Urinary Symptom Index Score and the rate of patients with pain 2 weeks after DJ and PSS. Secondary endpoints: to compare other USSQ scores and single answers 2 weeks after DJ and PSS, and DJ and PSS USSQ scores with baseline. RESULTS: 93 patients were enrolled. 2 weeks Urinary Symptom Index Score (p < 0.001) and the percentage of patients complaining of pain (60.2% vs 88.2%, p < 0.001) were significantly in favour of PSS compared to DJ. 2 weeks scores were significantly improved with PSS compared to DJ: Pain Index (p < 0.001), VAS (p < 0.001), General Health Index (p < 0.001) and Work Performance Index (p < 0.001). All urinary symptoms were significantly decreased with PSS, including renal pain during micturition and pain interfering with life. Pain Index Score (p = 0.622) and VAS (p = 0.169) were comparable to baseline with PSS, while differed with DJ. CONCLUSIONS: Patients undergoing DJ substitution with PSS after URS report a significant decrease of SRS. Urologists may consider positioning PSS after URS in pre-stented patients to reduce the impact of SRS.

Parenchymal renal rupture due to an obstructive ureteric calculus in an incompletely duplicated renal pelvis and ureter.

Introduction: Parenchymal renal rupture due to a ureteric calculus is extremely rare and an emergency. Case presentation: A 54-year-old man was brought to the emergency room with left back pain without trauma. Computed tomography showed left parenchymal renal rupture with an incompletely duplicated renal pelvis, ureter, and an 11-mm ureteric calculus in the ureterovesical junction. A ureteral stent was placed, and the patient was treated conservatively as his vital signs were stable. We performed transurethral lithotripsy after resolution of the perirenal hematoma. Conclusion: To best of our knowledge, this report is the first to present a case of parenchymal renal rupture due to a ureteric calculus in an incompletely duplicated renal pelvis and ureter. Ureteric calculus within an incompletely duplicated renal pelvis and ureter is at risk of parenchymal renal rupture. Therefore, the aggressive treatment of ureteric calculus could be important.

Spontaneous knot formation complication of double J: two case reports.

BACKGROUND: Use of ureteral stents has become an integral part of urological practice. However, it also brought with it many complications. Double J (DJ) stent knotting is a rare stent complication, and only a few cases have been reported in the literature. Although the exact cause is unknown and, in the literature, it is generally thought that knots occur due to traction. In this case report we present for the first time that spontaneous knots can occur due to ureteral peristalsis or ureteral anomalies. CASE PRESENTATION: Two patients (67 and 35 aged-Caucasian person) with ureteral stones who presented to the emergency department with colicky pain and had no previous history of urological surgery. We observed knot formation in the routine urinary system radiographs taken before stent removal in two patients whose ureters were observed to be narrow during endoscopic ureteral stone treatment. The stents were successfully removed using gentle traction under general anesthesia. CONCLUSIONS: We discussed the cause and solution of spontaneous knot formation. We emphasized the importance of the direct urinary system radiograph taken before DJ stent removal.

Forgotten ureteral stents: a systematic review of literature.

BACKGROUND: The forgotten ureteral stents (FUS) is one of the late complications of stent placement. This systematic review summarized different aspects of FUS and focused on the problems and solutions related to FUS. METHODS: This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. PubMed® and Embase® were searched from inception until October 1st, 2022. Eligible studies were those defining FUS as a stent unintentionally left in situ longer than at least 2 months. RESULTS: Total 147 studies with 1292 patients were finally included. The mean indwelling time of FUS was 33.5 months (range from 3 months to 32 years). The most common initial cause for stent placement was adjunct treatment to urolithiasis (79.2%). The major forgetting reasons were patient-related (83.9%), which included poor compliance, lapse in memory, and misconceptions about the necessity of timely removal. Primary presenting complaints were flank pain (37.3%), lower urinary tract symptoms (33.3%), and hematuria (22.8%). Encrustation (80.8%) and urinary tract infections (40.2%) were the most common complications detected in patients with FUS. Computed tomography evolving as a preferred imaging test (76.1%) was indispensable for evaluating encrustation, migration, fracture and other complicated situations in patients with FUS. Besides, evaluation of kidney function and infection status was also of great importance. Multiple and multimodal procedures (59.0%) were often necessitated to achieve the stent-free status, and were mostly endoscopic procedures. Cystoscope was most commonly used (64.8%). Retrograde ureteroscopy (43.4%) and antegrade stent removal (31.6%) were often used when dealing with more complicated situations. Extracorporeal shockwave lithotripsy (30.4%) was often used as adjunctive to other endoscopic procedures, but it sometimes failed. The decision regarding the choice of treatment is based on the volume and site of encrustation, the direction of migration, the site of fracture, kidney function and other urinary comorbidities. CONCLUSIONS: FUS not only pose hazard to patients' health, but also impose a huge economic burden on medical care. Thorough preoperative evaluation is fundamental to developing the treatment strategy. The management of FUS should be individualized using different treatment modalities with their advantages to minimize patients' morbidities. Prevention is better than cure. Strengthening health education and setting a tracking program are of great importance to the prevention of FUS.