Medizinischer Fachbereich —
Anwendung,
Publikationen & Downloads.
Anwendungsschritte von mediNiK®
Anwendung von mediNiK®
1. Navigieren Sie mit dem flexiblen oder semirigiden Ureterorenoskop in Sichtweite zu den Nierensteinfragmenten. Spülen Sie mit physiologischer steriler Kochsalzlösung (0,9 % NaCI), um eine gute Sicht zu gewährleisten.
2. Stoppen Sie die Spülung! Applizieren Sie die blaue Grundsubstanz K1 langsam impulsartig durch den Arbeitskanal des Endoskops bis die zu entfernenden Fragmente von blauem K1 komplett umschlossen sind. Wenn mehr als ein Nierenkelch betroffen ist, wiederholen Sie diesen Schritt für jeden Kelch einzeln.
Tipp: Verwenden Sie nur so viel von der blauen Grundsubstanz K1 wie nötig. Diese wird im Folgenden durch die Gabe der zweiten Komponente, des gelben Aktivators K2, zum Hydrogel.
3. Spülen Sie den Arbeitskanal des Endoskops vorsichtig mit 0,9 % NaCI.
Achtung! Vermeiden Sie eine Verwirbelung/Verdünnung des blauen K1 durch zu intensives Spülen des Arbeitskanals. Ziehen sie das Endoskop leicht zurück.
4. Applizieren Sie das gelbe K2 durch den vorher gespülten Arbeitskanal vorsichtig und langsam. Bewegen Sie das Endoskop langsam in Richtung des/der betroffenen Nierenkelch(e).
Achtung! Vermeiden Sie eine Verwirbelung des blauen K1 durch zu schnelle Zugabe. Unabhängig von der verwendeten Menge an blauer Grundsubstanz K1 sollte der gesamte Spritzeninhalt des gelben Aktivators K2 (11 ml) appliziert werden.
5. Führen Sie das Steinfangkörbchen (z.B. Dormia-, Tipless-Körbchen) über den Arbeitskanal des Endoskops ein.
6. Fassen und Entfernen Sie den Hydrogel-Clot vorsichtig mit dem Steinfangkörbchen. Die Spülung kann jetzt mit geringer Intensität wieder begonnen werden.
Achtung! Das Steinfangkörbchen kann das Hydrogel zerschneiden wenn es zu fest geschlossen wird.
Nach der Anwendung
Stellen Sie sicher, dass alle Hydrogel-Clots entfernt wurden. Sollten dennoch Hydrogel-Clots verbleiben, werden diese – in der Regel – durch die Diurese aufgelöst. Das Hydrogel kann auch aktiv durch die Zugabe eines Chelatbildners (z.B. EDTA) aufgelöst werden.
Wiederholung des Verfahrens: Falls das Verfahren wiederholt wird, muss das gesamte zuvor verwendete gelbe K2 vollständig aus der Niere gespült werden.
Einmalanwendung: mediNiK® – ist für die einmalige Anwendung bestimmt und darf nicht resterilisiert werden.
Entsorgung: Die Spritzen gefüllt mit dem blauen K1 und gelben K2 können nach den niedrigsten krankenhausinternen Entsorgungsstandards entsorgt werden. Das Hydrogel muss separat entsorgt werden, da es mit Schleimhäuten und/oder Urin in Berührung gekommen ist.
Hinweis
Alle im Zusammenhang mit dem Produkt auftretenden, schwerwiegenden Vorkommnisse müssen dem Hersteller und der zuständigen Behörde des Mitgliedsstaats, in dem der Anwender und/oder Patient niedergelassen ist, gemeldet werden (vigilanz@purenum.com).
Häufige Fragen zur Anwendung von mediNiK®
2. Wie viele Spritzen benötige ich pro Patient/Anwendung?
1 Anwendung = 2 Spitzen (1 x Komponente K1 + Komponente K2).
3. Woran kann man erkennen, dass eine ausreichende Menge der Grundsubstanz K1 appliziert wurde?
K1 ist blau eingefärbt und gleichzeitig transparent, so dass auf dem Monitor ein guter Farbkontrast entsteht und gleichzeitig die Steinfragmente sichtbar sind. Wenn alle Steinfragmente mit der blauen Komponente vollständig benetzt sind, wurde eine ausreichende Menge appliziert.
4. Woran kann man erkennen, dass eine ausreichende Menge des Aktivators K2 appliziert wurde?
Das Einhalten eines exakten Mischungsverhältnisses ist nicht erforderlich. Es sollte mindestens die zwei- bis dreifache Menge K2 im Vergleich zur vorher eingebrachten Grundsubstanz K1 appliziert werden. Da eine Überdosierung des Aktivators K2 nicht möglich ist, kann auch der gesamte Spritzeninhalt langsam (ohne Verwirbelung!) appliziert werden.
5. Kann man zu viel mediNiK® (K1 oder K2) applizieren?
Bei der Menge der Grundsubstanz K1 ist es sinnvoll nur so viel zu applizieren, um alle Fragmente vollständig zu umschließen nach dem Prinzip so viel wie nötig, so wenig wie möglich. Etwa 0,3 bis 0,5 ml von K1 sollten für einen Kelch ausreichen, wobei mehrere Kelche nacheinander gefüllt werden können, bevor K2 zugegeben wird. Von dem Aktivator K2 hingegen kann nicht „zu viel“ appliziert werden.
6. Nach Hinzufügen der Komponente K2 bildet sich kein festes Hydrogel bzw. es bildet sich nur wenig Hydrogel. Woran liegt das?
a. Spülung wurde vor der Applikation von K1 nicht ausgestellt und somit K1 weggespült oder verdünnt.
b. Die Komponente K2 wurde so schnell appliziert, dass die Komponente K1 durch die auftretende Verwirbelung weggespült wurde.
c. Die Komponente K2 wurde zu nah an der Komponente K1 appliziert, so dass die Komponente K1 weggespült wurde.
d. Es wurde zu wenig der Komponente K2 verwendet, keine sichtbare Gelbfärbung der kompletten Flüssigkeit in der Niere.
e. Wenn es nicht die erste Applikation ist: Mangelnde Spülung, es waren noch Reste der Komponente K2 in der Niere vorhanden.
7. Was passiert, wenn vor der Applikation von mediNiK® die Spülung NICHT abgestellt wird?
Die Grundsubstanz K1 wird von der durch die Spülung verursachten Strömung verwirbelt und weggespült oder verdünnt. Die zu bergenden Restfragmente sind somit ungenügend benetzt.
8. Was passiert, wenn ich eine Komponente nicht anwende?
Wird nur eine der beiden Komponenten appliziert, erfolgt keine Gelbildung. Demzufolge können die Restfragmente nicht wie erwartet geborgen werden.
9. Was passiert, wenn ich die Reihenfolge vertausche?
Wird zuerst der Aktivator K2 appliziert, erfolgt bei der nachfolgenden Applikation der Grundsubstanz K1 die Gelbildung augenblicklich. Die Restfragmente können somit nur ungenügend oder nicht in das Hydrogel eingebettet werden.
10. Muss ich Druck auf die Spritzen ausüben, damit die Komponenten aus den Spritzen herauskommen?
Die höher viskose Komponente K1 (Grundsubstanz) erfordert etwas mehr Kraftaufwand als die Komponente K2 (Aktivator), insbesondere wenn die Applikation durch einen Katheter erfolgt (was zum Beispiel bei Einsatz eines reusable Scopes sinnvoll sein kann). Bei der von uns empfohlenen Applikation direkt über den Arbeitskanal lassen sich beide Komponenten leicht dosieren. Sollte es nicht machbar sein die Komponenten K1 oder K2 (durch einen Katheter) zu applizieren, so ist möglicherweise:
1) der gewählte Katheter zu dünn;
2) eine Verstopfung im Katheter, ausgelöst durch Reste der jeweils anderen Komponente, welche nicht weggespült wurde;
3) der Tuohy Borst am Eingang des Arbeitskanal zu fest zugedreht ist, so dass der Querschnitt des Katheters reduziert ist.
11. Die Spritzen lassen sich beim erstmaligen Drücken schwer bewegen, ist dies normal?
Ja, zunächst muss der technisch-bedingte Druckpunkt gelöst werden. Dies erfolgt durch kurzes Eindrücken der Kolbenstange, wobei die Verschlusskappe z.B. durch Aufsetzen der Spritze auf eine feste Oberfläche fixiert wird, ähnlich wie bei anderen Spritzen der FARCO-PHARMA (z.B. Instillagel und Endosgel).
12. Kann mediNiK® ein zweites Mal während einer Operation angewendet werden?
Ja, mediNiK® kann sogar mehrmals an einem Patienten angewendet werden. Hierfür müssen der Arbeitskanal des Endoskops und die Niere sorgfältig mit einer physiologischen Kochsalzlösung gespült werden, so dass keine Reste der Komponente K2 vorhanden sind. Reste von K2 würden bei der erneuten Applikation von K1 zu einer sofortigen Gelbildung führen, ohne die Steinfragmente ausreichend benetzen zu können.
Bergung der Nierensteinfragmente
14. Warum muss der Hydrogel-Clot „vorsichtig“ rausgezogen werden? Was ist, wenn ich die Hälfte „verliere“?
Das Hydrogel ist weich eingestellt, damit es sich an die Harnwege bzw. Ureteralschleuse anpassen kann. Gerade beim Übergang vom Nierenbecken in die Ureteralschleuse befindet sich eine Engstelle. Wird das Hydrogel hier zu schnell durchgezogen, kann der aus dem Fangkörbchen herausragende Teil abgeschert werden. Dieser Teil muss in einem weiteren Schritt geborgen werden. Aufgrund der Lokalisierung direkt im Nierenbecken ist das Greifen und anschließende Bergen einfach durchzuführen.
15. Was passiert, wenn Reste von mediNiK® nach dem Eingriff in der Niere verbleiben?
In der Niere verbleibende Reste von mediNiK® stellen keine Gefährdung des Patienten dar. Die natürliche Diurese kehrt die Gelbildung um. Zunächst wird das Gel immer weicher, bis es wieder vollständig zu einer Flüssigkeit und vom Patienten mit dem Urin ausgeschieden wird.
Nach der Anwendung
17. Können Reste von mediNiK® für eine weitere OP verwendet werden?
Nein. Es gilt das Prinzip, dass geöffnete und verwendete Spritzen nur am selben Patienten in derselben OP verwendet werden dürfen.
18. Wie kann ich die geborgenen Steinfragmente aus dem Hydrogel isolieren, um sie einer Analytik unterziehen zu können?
Es gibt prinzipiell 2 Möglichkeiten:
1) Die Steine können mechanisch aus dem Hydrogel herausgenommen werden und mit ausreichend Wasser abgespült werden.
2) Das Hydrogel wird durch Einlegen in einem Chelatbildner (z.B. EDTA) aufgelöst und soll mit Wasser gewaschen werden, so dass Steinfragmente isoliertfür die Analytik zur Verfügung stehen.
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Publikationen
ZU mediNiK®
Stone extraction during flexible ureterorenoscopy with or without the hydrogel method: a randomized, multicenter safety and feasibility study
Amiel T, Neisius A, Netsch C, Secker A, Fisang C, Grunwald I, Lunger L, Straub M. Stone extraction during flexible ureterorenoscopy with or without the hydrogel method: a randomized, multicenter safety and feasibility study. World J Urol. 2025 Oct 31;43(1):655. doi: 10.1007/s00345-025-06011-7 PMID: 41171315
Brief summary of results:
Purpose
Achieving the highest possible stone-free rate is the primary goal of kidney stone surgery, yet standard flexible ureterorenoscopy often leaves small residual fragments that predispose to recurrence. The hydrogel method using mediNiK® was developed to embed and extract even the smallest fragments with conventional baskets. This study aimed to evaluate the safety and feasibility-defined as the ability to extract fragments < 1 mm-of stone extraction during flexible ureterorenoscopy with or without the hydrogel method.
Materials and methods
This prospective, randomized, multicenter proof-of-concept trial included patients > 18 years with kidney stones > 8 mm and no anatomical abnormalities. Patients were randomized to flexible ureterorenoscopy + hydrogel (Group 1) or flexible ureterorenoscopy (Group 2) alone. After laser lithotripsy, fragments were retrieved either embedded in hydrogel or individually, and categorized by size (< 0.5 mm, 0.5-1.0 mm, > 1.0 mm). Explorative statistical analyses included Mann-Whitney U, Student’s t-test, and Chi-square test. Adverse events were monitored intraoperatively and during a 6-week follow-up.
Results
Of 65 screened patients, 40 were analysed (Group 1: n = 23; Group 2: n = 17). The hydrogel method significantly retrieved more fragments < 1 mm (1716 vs. 209) and > 1 mm (310 vs. 118). On a per-patient level, more < 1 mm fragments were removed in Group 1 (median 7 [IQR 21] vs. 0 [2], p < 0.003). Surgery duration was longer in Group 1 (80 [28] vs. 62 [20] minutes, p = 0.02). No serious adverse events were reported.
Conclusions
The hydrogel method was a safe and feasible addition to fURS, allowing improved retrieval of even the smallest fragments without added risk. The main limitations are the small sample size and absence of long-term stone-free and recurrence data, underscoring the need for larger confirmatory studies.
Novel Biocompatible Adhesive to Remove Stone Dust:
Usability Trial in a Kidney Model
Hausmann T, Becker B, Gross AJ, Netsch C, Rosenbaum CM. Novel Biocompatible Adhesive to Remove Stone Dust: Usability Trial in a Kidney Model. J Endourol. 2021 Aug;35(8):1223-1228. doi: 10.1089/end.2020.0748. Epub 2021 Apr 15. PMID: 33559523.
Brief summary of results:
Introduction and Objective
“Clinically insignificant residual fragments” are an independent predictive factor for recurrence of nephrolithiasis. To improve the stone-free rates (SFR), we tested the viability of a novel bioadhesive system for intrarenal embedding and retrieval of residual fragments <1 mm in a kidney model.
Materials and Methods
All procedures were performed in a standardized setting, including a kidney model (Kidney module right, Samed GmbH, Dresden) in a plastic basin filled with water. We used a Viper URF flexible ureterorenoscope (fURS) (6.6/8F, Richard Wolf, Knittlingen). A mean amount of 138 mg (standard deviation [SD] ±32.2 mg) of sand grains (range, 0.2–0.8 mm) was inserted in renal calices of the kidney model. We assessed the extraction efficacy of fURS using the bioadhesive system. In total, eight different surgeons performed each one trial, respectively. The endoscopic and macroscopic SFR, the level of the surgeons‘ experience, and the overall time of stone retrieval were evaluated. Additionally, a survey of the participants was conducted, to assess the contentment with this novel system.
Results
The extraction of the sand grains was only possible using the bioadhesive system, otherwise they were too small sized to grab with a retrieval basket. The total SFR was 84% (SD ±11.7%). The operation time (p = 0.052) and the percentage of extracted sand grains (p = 0.194) were not significantly different between experienced and less experienced surgeons. All participants stated that it was a promising technique, which they could imagine using on a daily basis.
Conclusions
The bioadhesive system improves the SFR with fragments from 0.2 to 0.8 mm (0% vs 84%). Also, the performance of this operation is not dependent on the surgeon’s experience level. This method might improve the SFR in difficult anatomic conditions, that is, lower calices or anomalous kidneys.
Viability and biocompatibility of an adhesive system for intrarenal embedding and endoscopic removal of small residual fragments in minimally-invasive stone treatment in an in vivo pig model
Hein S, Schoeb DS, Grunwald I, Richter K, Haberstroh J, Seidl M, Bronsert P, Wetterauer U, Schoenthaler M, Miernik A. Viability and biocompatibility of an adhesive system for intrarenal embedding and endoscopic removal of small residual fragments in minimally-invasive stone treatment in an in vivo pig model. World J Urol. 2018 Apr;36(4):673-680. doi: 10.1007/s00345-018-2188-8. Epub 2018 Jan 24. PMID: 29368229.
Brief summary of results:
Purpose
To evaluate the viability and biocompatibility of a novel, patented bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy. Complete stone clearance via active removal of residual fragments (RF) after intracorporeal laser lithotripsy may be time-consuming and fail in many cases. Therefore, the novel adhesive has been developed and evaluated for the first time in an in vivo pig model in the present work.
Methods
Four female domestic pigs underwent flexible ureteroscopy (RIRS) or percutaneous nephrolithotomy (PNL) under general anesthesia (8 kidneys, 4 × RIRS, 4 × PNL) evaluating the bioadhesive system. Interventions: RIRS without adhesive system (sham procedure, kidney I); 3 × RIRS using the bioadhesive system (kidneys II–IV); and 4 × PNL using the bioadhesive system (V–VIII). We endoscopically inserted standardized human stone probes followed by comminution using Ho:YAG lithotripsy. The bioadhesive (kidney II–VIII) was then applied and the adhesive-stone fragment complex extracted. After nephrectomy, all kidneys were evaluated by two independent, blinded pathologists. Endpoints were the procedure’s safety and adhesive system’s biocompatibility.
Results
We observed no substantial toxic effects. We were able to embed and remove 80–90% of fragments. However, because of the pig’s hampering pyelocaliceal anatomy, a quantified, proportional assessment of the embedded fragments was compromised.
Conclusions
For the first time, we demonstrated the proven feasibility and safety of this novel bioadhesive system for embedding and endoscopically removing small RF in conjunction with a lack of organ toxicity in vivo.
New for Old–Coagulum Lithotomy vs a Novel Bioadhesive for Complete Removal of Stone Fragments in a Comparative Study in an Ex Vivo Porcine Model
Schoeb DS, Schoenthaler M, Schlager D, Petzold R, Richter K, Grunwald I, Wetterauer U, Miernik A, Hein S. New for Old-Coagulum Lithotomy vs a Novel Bioadhesive for Complete Removal of Stone Fragments in a Comparative Study in an Ex Vivo Porcine Model. J Endourol. 2017 Jun;31(6):611-616. doi: 10.1089/end.2017.0125. Epub 2017 May 8. PMID: 28385037.
Brief summary of results:
Objectives
To evaluate a recently reported new bioadhesive system for the retrieval of small residual fragments (RFs) after intracorporeal lithotripsy, we systematically compared this system with coagulum lithotomy in retrograde intrarenal surgery.
Materials and Methods
We extracted 30 human stone fragments (≤1 mm) in an ex vivo porcine kidney model using a flexible ureteroscope for three groups: (1) the novel bioadhesive, (2) autologous blood as a natural adhesive, and (3) (control group) a conventional retrieval basket. Each group consisted of 15 test runs. Outcomes were evaluated regarding the macroscopic stone-free rate (SFR), retrieval time, and number of ureteral passages.
Results
For groups 1 and 2, a significant advantage in stone clearance, mean retrieval time, and number of retrievals was detected compared to the control group (p = 0.001). The time and number of retrievals were significantly lower in group 1 (10:36 minutes, p = 0.001) than in group 2 (26:12 minutes, p = 0.001), with shorter clotting time and better visibility.
Conclusions
These data show the general feasibility of intrarenal RF embedding to improve the SFR. Our data furthermore suggest the superiority of the artificial bioadhesive embedding agent over the application of native blood. Further in vivo studies and other research are necessary to confirm the adhesive’s effect in patients.
Novel Biocompatible Adhesive for Intrarenal Embedding and Endoscopic Removal of Small Residual Fragments after Minimally Invasive Stone Treatment in an Ex Vivo Porcine Kidney Model: Initial Evaluation of a Prototype
Hein S, Schoenthaler M, Wilhelm K, Schlager D, Thiel K, Brandmann M, Richter K, Grunwald I, Wetterauer U, Miernik A. Novel Biocompatible Adhesive for Intrarenal Embedding and Endoscopic Removal of Small Residual Fragments after Minimally Invasive Stone Treatment in an Ex Vivo Porcine Kidney Model: Initial Evaluation of a Prototype. J Urol. 2016 Dec;196(6):1772-1777. doi: 10.1016/j.juro.2016.05.094. Epub 2016 May 30. PMID: 27256206.
Brief summary of results:
Purpose
Residual fragments related to endoscopic intracorporeal lithotripsy are a challenging problem. The impact of residual fragments remains a subject of discussion and growing evidence highlights that they have a central role in recurrent stone formation. Therefore, we developed a novel bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy in an ex vivo porcine kidney model.
Materials and Methods
In a standardized setting 30 human stone fragments 1 mm or less were inserted in the lower pole of an ex vivo porcine kidney model. We assessed the extraction efficacy of flexible ureteroscopy using the bioadhesive system in 15 preparations and a conventional retrieval basket in 15. Outcomes were compared regarding the endoscopic and macroscopic stone-free rate, and overall time of retrieval.
Results
Embedding and retrieving the residual fragment-bioadhesive complex were feasible in all trial runs. We observed no adverse effects such as adhesions between the adhesive and the renal collecting system or the instruments used. The stone-free rate was 100% and 60% in the bioadhesive and conventional retrieval groups, respectively (p = 0.017). Mean retrieval time was significantly shorter at 10 minutes 33 seconds vs 36 minutes 56 seconds in the bioadhesive group vs the conventional group (p = 0.001).
Conclusions
This novel method involving adhesive based complete removal of residual fragments from the collecting system has proved to be feasible. Our evaluation in a porcine kidney model revealed that this technology performed well. Further tests, including inpatient studies, are required to thoroughly evaluate the benefit and potential drawbacks of bioadhesive based extraction of residual fragments after intracorporeal lithotripsy.
zum medical need
Stone-event-free survival after retrograde intrarenal surgery: is the stone-free-status so relevant for the future outcomes?
Mesquita S, Mendes G, Marques-Monteiro M, Rocha MA, Madanelo M, Fraga A, Cavadas V. Stone-event-free survival after retrograde intrarenal surgery: is the stone-free-status so relevant for the future outcomes? Int Urol Nephrol. 2025 May;57(5):1473-1480. doi: 10.1007/s11255-024-04343-8. Epub 2024 Dec 28. PMID: 39731646
Brief summary of results:
Introduction
The primary aim of stone treatment is to achieve stone-free status. Residual fragments can cause stone growth, recurrence, urinary tract infections, and ureteric obstruction. Our goal was to describe the natural history of stone burden after retrograde intrarenal surgery (RIRS) based on stone-free status (SFS), evaluating stone growth and stone-events.
Methods
We retrospectively reviewed data from patients who underwent RIRS at a tertiary care center between October 2014 and September 2019. The stone burden was assessed by measuring the maximum diameter (mm) and volume (mm3). Patients were divided into four groups according to SFS-(A) absolute stone-free, no stones on non-contrast-enhanced computed tomography (NCCT); (B) relative stone-free with ≤ 2 mm fragments, (C) relative stone-free with 2.1-4 mm fragments, and (D) residual fragments > 4 mm. Our main outcomes were stone growth over time (defined as an increase in diameter compared to first postoperative measurement) and incidence of stone-related events (pain or additional intervention to treat symptoms, obstruction, or removing fragments).
Results
A total of 98 patients were included in the study-42 were classified as absolute stone-free (Group A), 20 were categorized as relatively stone-free (Groups B and C), and 36 had a residual stone burden with fragments larger than 4 mm (Group D) on postoperative NCCT. There was a significant difference in the number of stones among the groups (p < 0.001). The pre-operative stone volume differed significantly among the groups (p = 0.003). Group A had the lowest median total stone volume (551.3 mm3). Twenty patients (20.4%) developed stone-events during a mean follow-up period of 62.3 months (± 26.0). Stone-event-free survival differed significantly between the groups (p = 0.028), with Group D demonstrating a higher incidence of stone-related events post-RIRS compared to the other groups. Sixteen patients (16.3%) had renal colic requiring a hospital visit across all groups. Thirteen patients (13.3%) required re-intervention (3 patients belonged to Group A, 1 to Group B, 2 to Group C, and 7 to Group D).
Conclusions
Group D shows a higher rate of stone-related events post-RIRS. Ensuring complete stone-free status after RIRS is crucial for treatment success. Other factors should be considered in the management, including ensuring compliance with general preventive measures and stone-specific pharmacological treatments to prevent recurrence.
Endoscopically Determined Stone Clearance Predicts Disease Recurrence Within 5 Years After Retrograde Intrarenal Surgery
Hein S, Miernik A, Wilhelm K, Schlager D, Schoeb DS, Adams F, Vach W, Schoenthaler M. Endoscopically Determined Stone Clearance Predicts Disease Recurrence Within 5 Years After Retrograde Intrarenal Surgery. J Endourol. 2016 Jun;30(6):644-9. doi: 10.1089/end.2016.0101. Epub 2016 Apr 22. PMID: 27021947.
Brief summary of results:
Objective
To assess stone-related events (SREs) requiring retreatment in a series of 100 consecutive patients treated by retrograde intrarenal surgery (RIRS) for renal stones and to evaluate potential risk factors thereof.
Patients and Methods
The primary outcome was incidence of SRE (medical or surgical treatment). Secondary outcomes included side of SRE, time to SRE, and late complications. Analysis of potential risk factors included high-risk stone formers (HRSFs), obesity, high stone burden, and lower pole stones. In addition, we evaluated endoscopically determined small residual fragments (SRF) of <1 mm (i.e., fragments too small for retrieval) as an independent risk factor.
Results
Eighty-five of the 99 patients were followed up for a mean of 59 months (31–69), among whom 26 (30.1%) had SRE. Thirty-four of the 85 (40%) patients were HRSFs, 22 of whom experienced SRE (both sides) during follow-up (64.7%, p < 0.001). Eight of the 17 patients (47.1%) with SRF experienced ipsilateral side SRE compared with 13 (19.1%) of the 68 without SRF (p = 0.022, hazard ratio 2.823, 95% confidence interval [95% CI] 1.16, 6.85). Risk for ipsilateral SRE was unaffected by the presence of SRF among HRSFs (p = 0.561). Of low-risk patients with SRF, 33.3% experienced ipsilateral SRE, while those without SRF experienced no ipsilateral SRE (p < 0.001).
Conclusion
Endoscopically determined stone clearance predicts disease recurrence within 5 years after RIRS. Even SRF are an important risk factor for future stone-related (ipsilateral) events; therefore, patients with residual fragments of any size should not be labeled “stone free” and endoscopic stone treatment should aim at complete stone clearance.
Natural History of Post-Treatment Kidney Stone Fragments: A Systematic Review and Meta-Analysis
Brain E, Geraghty RM, Lovegrove CE, Yang B, Somani BK. Natural History of Post-Treatment Kidney Stone Fragments: A Systematic Review and Meta-Analysis. J Urol. 2021 Sep;206(3):526-538. doi: 10.1097/JU.0000000000001836. Epub 2021 Apr 27. PMID: 33904756.
Brief summary of results:
Purpose
We assessed the literature around post-treatment asymptomatic residual stone fragments and performed a meta-analysis. The main outcomes were intervention rate and disease progression.
Materials and Methods
We searched Ovid®, MEDLINE®, Embase™, the Cochrane Library and ClinicalTrials.gov using search terms: “asymptomatic”, “nephrolithiasis”, “ESWL”, “PCNL”, “URS” and “intervention.” Inclusion criteria were all studies with residual renal fragments following treatment (shock wave lithotripsy, ureteroscopy or percutaneous nephrolithotomy). Analysis was performed using ‘metafor’ in R and bias determined using Newcastle–Ottawa scale.
Results
From 273 articles, 18 papers (2,096 patients) had details of intervention rate for residual fragments. Aggregate intervention rates for ≤4 mm fragments rose from 19% (20 months) to 22% (50 months), while >4 mm fragments rose from 22% to 47%. Aggregate disease progression rates for ≤4 mm rose from 25% to 47% and >4 mm rose from 26% to 88%. However, there was substantial difference in definition of “disease progression.” Meta-analysis comparing >4 mm against ≤4 mm fragments: intervention rate for >4 mm (vs ≤4 mm): OR=1.50 (95% CI 0.70–2.30), p <0.001, I2=67.6%, tau2=0.48, Cochran’s Q=11.4 (p=0.02) and Egger’s regression: z=3.11, p=0.002. Disease progression rate for >4 mm: OR=0.06 (95% CI −0.98–1.10), p=0.91, I2=53.0%, tau2=0.57, Cochran’s Q=7.11 (p=0.07) and Egger’s regression: z=−0.75, p=0.45. Bias analysis demonstrated a moderate risk.
Conclusions
Larger post-treatment residual fragments are significantly more likely to require further intervention especially in the long term. Smaller fragments, although less likely to require further intervention, still carry that risk. Notably, there is no significant difference in disease progression between fragment sizes. Patients with residual fragments should be appropriately counselled and informed decision-making regarding further management should be done.
Clearance rates of residual stone fragments and dusts after endoscopic lithotripsy procedures using a holmium laser: 2-year follow-up results
Kang M, Son H, Jeong H, Cho MC, Cho SY. Clearance rates of residual stone fragments and dusts after endoscopic lithotripsy procedures using a holmium laser: 2-year follow-up results. World J Urol. 2016 Nov;34(11):1591-1597. doi: 10.1007/s00345-016-1807-5. Epub 2016 Mar 21. PMID: 27000560.
Brief summary of results:
Purpose
To investigate the spontaneous clearance rates of remnant particles following miniaturized percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS).
Methods
Among 624 patients who underwent mini-PCNL or RIRS at our institution from 2011 to 2015, we collected data of 247 patients with 2 years of follow-up. Of these, we included 148 patients with unilateral renal stones between 10 and 30 mm, as well as remnant particles after surgery. The size criteria of dusts and residual fragments (RFs) were, respectively, <1 and <3 mm.
Results
After excluding 22 patients, 126 patients (RFs = 21, dusts = 98, and both RFs and dusts = 7) were analyzed. Mean age was 56.5 (±14.4) years, and mean stone size was 19.5 (±12.5) mm. The mean follow-up period was 18.5 (± 12.9) months. In patients whose remnant particles were naturally eliminated following lithotripsy, the mean stone passage time was 9.0 (±9.3) months in the dusts and 13.9 (±11.1) months in the RFs groups (P = 0.135). Remnant particles disappeared in 42 out of 105 patients (40.0 %) in dusts and 7 out of 28 patients (25.0 %) in RFs groups (P = 0.187). The size of dusts and RFs increased, respectively, in 18.1 % (19/105) and 28.6 % (8/28) of patients with remnant particles during the follow-up period.
Conclusions
The presence of dusts and RFs was poor prognostic factors in patients underwent renal stone surgery using a holmium laser. Complete residual stone removal by using a basket or dusts eradication by irrigation for an adequate time during surgery can be a good surgical strategy.
Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse
Sorensen MD, Harper JD, Borofsky MS, Hameed TA, Smoot KJ, Burke BH, Levchak BJ, Williams JC Jr, Bailey MR, Liu Z, Lingeman JE. Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse. N Engl J Med. 2022 Aug 11;387(6):506-513. doi: 10.1056/NEJMoa2204253. PMID: 35947709; PMCID: PMC9741871.
Brief summary of results:
Background
The benefits of removing small (≤6 mm), asymptomatic kidney stones endoscopically is unknown. Current guidelines leave such decisions to the urologist and the patient. A prospective study involving older, nonendoscopic technology and some retrospective studies favor observation. However, published data indicate that about half of small renal stones left in place at the time that larger stones were removed caused other symptomatic events within 5 years after surgery.
Methods
We conducted a multicenter, randomized, controlled trial in which, during the endoscopic removal of ureteral or contralateral kidney stones, remaining small, asymptomatic stones were removed in 38 patients (treatment group) and were not removed in 35 patients (control group). The primary outcome was relapse as measured by future emergency department visits, surgeries, or growth of secondary stones.
Results
After a mean follow-up of 4.2 years, the treatment group had a longer time to relapse than the control group (P<0.001 by log-rank test). The restricted mean (±SE) time to relapse was 75% longer in the treatment group than in the control group (1631.6±72.8 days vs. 934.2±121.8 days). The risk of relapse was 82% lower in the treatment group than the control group (hazard ratio, 0.18; 95% confidence interval, 0.07 to 0.44), with 16% of patients in the treatment group having a relapse as compared with 63% of those in the control group. Treatment added a median of 25.6 minutes (interquartile range, 18.5 to 35.2) to the surgery time. Five patients in the treatment group and four in the control group had emergency department visits within 2 weeks after surgery. Eight patients in the treatment group and 10 in the control group reported passing kidney stones.
Conclusions
The removal of small, asymptomatic kidney stones during surgery to remove ureteral or contralateral kidney stones resulted in a lower incidence of relapse than nonremoval and in a similar number of emergency department visits related to the surgery. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Veterans Affairs Puget Sound Health Care System; ClinicalTrials.gov number, NCT02210650.)
The Predictive Factors for Readmission and Rehospitalization After Retrograde Intrarenal Surgery: The Results of RIRSearch Study Group
Dogan C, Yazici CM, Akgul HM, Ozman O, Basatac C, Cinar O, Siddikoglu D, Cakir H, Elmaagac B, Sancak EB, Onal B, Akpinar H. The Predictive Factors for Readmission and Rehospitalization After Retrograde Intrarenal Surgery: The Results of RIRSearch Study Group. J Endourol. 2022 Jan;36(1):56-64. doi: 10.1089/end.2021.0327. Epub 2021 Dec 9. PMID: 34235975.
Brief summary of results:
Purpose
Retrograde intrarenal surgery (RIRS) is a safe and effective treatment option for upper urinary tract stones smaller than 2 cm. Although several studies have documented perioperative and postoperative complications related to RIRS, there exists limited data regarding the readmission and rehospitalization of patients after RIRS. The aims of the study were to document the rates of readmission and rehospitalization after RIRS and to determine the predictive factors for readmission and rehospitalization.
Materials and Methods
In this study, we retrospectively analyzed patients who underwent RIRS for the treatment of renal stone disease and were unexpectedly readmitted to the hospital within 30 days after discharge. The hospital admission systems were used to determine readmissions and rehospitalizations. Readmission and rehospitalization rates, causes, and treatment procedures were evaluated. Univariate and multivariate analyses of clinicodemographic properties were performed to evaluate possible predictive factors for readmission and rehospitalization after RIRS.
Results
A total of 1036 patients were included in the study. Of these patients, 103 (9.9%) were readmitted to the hospital. Among these readmissions, 35 patients (33.9%) were rehospitalized and 14 (13.6%) underwent surgical intervention. The most common reasons for readmission were renal colic and fever. The presence of preoperative pyuria (odds ratio [OR] 1.86), stone volume (OR 1.54), postoperative complications (OR 3.66), and stone-free status (OR 0.46) were predictive factors for readmission, whereas hospitalization time (OR 1.32), postoperative complications (OR 9.70), and stone-free status (OR 0.06) were predictive factors for rehospitalization after RIRS.
Conclusion
Nearly 10% of patients who underwent RIRS were readmitted to the hospital within the first month after discharge, and some were rehospitalized. Preoperative pyuria, high stone volume, presence of postoperative complications, and low stone-free status predicted this readmission and rehospitalization. Clinicians must recognize these predictive factors and inform their patients about this possibility.
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