Robotic ureteral reconstruction of non-absorbable clip erosion into the ureter: a case series

Introduction

Non-absorbable surgical clips are commonly utilized in urological surgery to ligate vasculature and lymphatics (1). Delayed migration of non-absorbable surgical clips into the urinary tract is a rare but potentially morbid complication that may lead to pain, infection (2-4), stone formation (5-16), and urinary obstruction (17-19). When non-absorbable clip erosion into the urinary tract occurs, it most often occurs in a delayed fashion into the lower urinary tract (i.e., urethra, bladder neck, and bladder) after use of non-absorbable clips to control the lateral prostatic pedicles during radical prostatectomy (17,18,20-22). Non-absorbable clip migration into the upper urinary tract is even more uncommon, and the literature regarding this complication is limited to a handful of case reports (3,4,11-15,19,23-25). This complication may be particularly detrimental given the relatively small diameter of the ureters, which may increase the likelihood of the eroded clip to cause obstructive uropathy. Furthermore, reconstruction of a ureter that is obstructed secondary to clip erosion can be particularly challenging given the history of prior surgery in proximity to the ureter and inflammatory reaction from the non-absorbable clip itself. Herein, we describe our surgical approach and experience with robotic ureteral reconstruction (RUR) of patients with non-absorbable clip erosion into the ureter, presented in accordance with the AME Case Series reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-24-485/rc).

Case presentation

Study population

We performed a retrospective review of all patients who underwent RUR for ureteral obstruction secondary to non-absorbable clip migration between September 2022 and April 2024. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki (as revised in 2013). Publication of this case series was waived from patient consent according to the Northwestern University institutional review board (No. STU00216708). Ureteral obstruction was defined as T1/2>20 minutes on Tc-99m mercaptoacetyltriglycine (MAG3) Lasix renal scan and/or flank pain in association with ureteral narrowing on endoscopic visualization (inability to pass 7-Fr ureteroscope across narrowing). We defined the proximal ureter as the portion that spanned the ureteropelvic junction to the upper border of the sacroiliac joint, the middle ureter as the portion that spanned the upper border of the sacroiliac joint to the lower border of the sacroiliac joint, and the distal ureter as the portion that spanned the lower border of the sacroiliac joint to the bladder. All procedures were non-consecutively performed by a single surgeon (Z.L.) at a single academic center using the da Vinci® surgical platform (Intuitive Surgical, Sunnyvale, CA, USA). Postoperatively, all patients had stents in place for six weeks. Patient demographics and perioperative outcomes were analyzed using descriptive statistics. Stricture length was determined intraoperatively using a ruler placed intracorporeally at time of reconstruction. The primary outcome was surgical success, defined as the absence of symptoms from ureteral obstruction and the absence of ureteral obstruction on functional imaging (T1/2 >20 minutes). Postoperatively, patients were assessed for surgical success at 3 months, 12 months, and 18 months, and then yearly thereafter.

Surgical technique

The specific surgical technique used during RUR depended on intraoperative determination of viable ureteral lumen at the site of clip erosion (Figures 1,2). More specifically, when clip erosion involved <80% of the ureteral circumference on visual intraoperative endoscopic evaluation, we favored a non-transecting repair and performed an onlay buccal mucosa graft (BMG) ureteroplasty. In such cases, there was adequate residual healthy ureteral lumen to perform an onlay-type repair to allow for BMG take and minimize disruption of the longitudinal ureteral blood supply. After removing the eroded clip(s), the surrounding inflamed tissue suboptimal for reconstruction is excised longitudinally, and the ureterotomy is extended proximally and distally until healthy tissue is reached. The resulting ureterotomy is measured using a ruler and a BMG is harvested to the exact length of the resulting defect and width of 1.0–1.5 cm. We harvested the BMG through hydrodissection with lidocaine and epinephrine and sharp excision from the buccinator muscle. The BMG is then anastomosed to the ureter using two running 5-0 monofilament absorbable sutures (Figure 3). After completing half of the anastomosis, we inserted a double-J ureteral stent under direct visualization into the ureter. We previously described our approach to harvesting a BMG and our technique for robotic onlay BMG ureteroplasty (26).

Figure 1 Determination of surgical technique. Selection of the type of surgical treatment for clip erosion required intraoperative assessment of the amount of viable ureteral lumen. BMG, buccal mucosal graft.

Figure 2 Endoscopic view of clip erosion. (A) Ureteroscopic view of ureteral lumen <80% involvement by stricture. (B) Ureteroscopic view of ≥80% ureteral lumen involvement.

Figure 3 BMG ureteroplasty. (A) Clip erosion at the ureteropelvic junction, repaired with BMG ureteroplasty. (B) Ureter is demarcated in yellow, and the graft is shaded in blue. BMG, buccal mucosal graft.

When clip erosion involved ≥80% of the ureteral circumference, we favored a transecting repair. In such cases, there was inadequate ureteral lumen to perform a non-transecting repair, so the longitudinal ureteral blood supply was not preserved, and the ureter was transected. Clip erosions in the middle and distal ureters were reconstructed using ureteral reimplantation with adjunctive maneuvers such as a psoas hitch and/or Boari flap. After removing the eroded clip(s) to evaluate the extent of ureteral injury, the ureter was transected at the level of the normal ureter above the level of the clip erosion. The bladder was dropped off the anterior abdominal wall, rotated towards the ipsilateral psoas muscle, and pexed to the ipsilateral psoas minor tendon (if present) or psoas major fascia using 2-0 barbed absorbable suture. We preserved the bilateral superior vesical arteries to maintain the fragile blood supply of the ureter. If nephrolithiasis was present, the stones were ureteroscopically removed. In cases when we were unable to perform a tension-free anastomosis using a psoas hitch, we performed a Boari flap using a 1:1 length to width ratio (Figure 4). The ureter was anastomosed to the bladder using two running 5-0 monofilament absorbable sutures. The techniques we utilized for robotic reimplantation with psoas hitch and Boari flap have previously been described (27,28).

Figure 4 Boari flap reconstruction. Ureter is demarcated in yellow, and the bladder is outlined in blue. (A) Partially completed Boari flap for mid ureteral stricture from clip erosion. (B) Completed Boari flap reconstruction.

Results

During the study period, six patients underwent RUR for ureteral obstruction secondary to non-absorbable clip erosion. The median age at time of surgery was 51.5 years (IQR, 40.3–61.3). The median length of time between placement of non-absorbable clip and clip erosion diagnosis was 90.5 months (IQR, 48.4–219.1). Three patients (50%) presented with flank pain, 2/6 (33.3%) patients presented with stone formation, and 1/6 (16.7%) patients presented with gross hematuria. All patients were found to have evidence of ureteral obstruction. The non-absorbable clip that eventually eroded was initially placed at the time of robotic pyeloplasty in 3/6 (50.0%) patients, open pyeloplasty in 1/6 (16.7%) patients, robotic radical prostatectomy in 1/6 (16.7%) patients, and upper pole nephroureterectomy in 1/6 (16.7%) patients. Clip erosion occurred in the proximal ureter in 4/6 (66.7%) patients, middle ureter in 1/6 (16.7%) patients, and distal ureter in 1/6 (16.7%) patients. Patient characteristics are summarized in Table 1.

Four patients with proximal ureteral clip erosion had <80% of ureteral circumference affected, and robotic onlay BMG ureteroplasty was performed. Among these patients, the median stricture length was 2.3 cm (IQR, 2.0–2.6). Median operative time was 140 minutes (IQR, 123–156), median length of stay was 1 day (IQR, 0.8–1.0), and median estimated blood loss was 37.5 mL (IQR, 25–50).

Two patients with mid and distal ureteral clip erosion had ≥80% of the ureteral circumference affected. The patient with middle ureteral clip erosion presented with two strictures on the same side—the mid-ureteral stricture caused by clip erosion and a proximal ureteral stricture from stone disease. The proximal ureteral stricture was repaired with 4.0 cm of buccal onlay. For the mid-ureteral stricture, ureteroscopy showed that the surgical clip at the mid-ureter extended 4.0 cm distally. Additionally, there was severe fibrosis at the level of the surgical clip that was carefully removed off the ureter. Distal to the clip erosion, there was evidence of ureteral devascularization likely secondary to prior ureteroscopy for nephrolithiasis. Ureteral pathology at the level of the mid-ureteral stricture was 3.5 cm. This patient underwent a Boari flap for the mid-ureteral stricture given the length of the ureteral stricture. Operative time was 371 minutes, estimated blood loss was 150 milliliters, and length of stay was 1 day. The patient with distal ureteral clip erosion underwent robotic ureteral reimplantation with psoas hitch and concomitant robotic removal of peri-prostatic cyst. Operative time was 375 minutes, estimated blood loss was 250 milliliters, and length of stay was 1 day. None of the patients experienced an intraoperative or major (Clavien >2) postoperative complications. At a median follow up of 14.8 months (IQR, 10.1–18.7), all patients were surgically successful. Perioperative outcomes are summarized in Table 1.

Discussion

Non-absorbable clip erosion into the ureter is a rare but potentially morbid complication. Clip erosion into the ureter can be particularly problematic because the caliber of the ureter is narrow, and obstruction can easily occur. While clip erosions have been described for various urologic conditions in addition to ureteral obstruction such as bladder neck erosions (17), the driving factor behind clip erosion is poorly understood. It is possible that clip erosions originate from a foreign body reaction. Suturing materials are known to provoke a local inflammatory response, especially for non-absorbable materials which may scar and encapsulate (29); however, less evidence exists on foreign body reactions associated with surgical clip use. Nevertheless, one prior study has identified inflammation at 28 days following the use of Hem-o-lok clips in mouse models (30). While clip erosions into the ureter are rare, it is possible that this pathology originates from a similar foreign body reaction.

Currently, there are only nine case reports detailing clip erosion of the ureter which are summarized in Table 2 (3,4,11-15,19,23). Although all prior reports noted the successful ability to remove eroded clips, 2/9 (22%) cases required reoperation for complications related to initial endoscopic clip removal. Finley et al. described a 48-year-old woman who developed erosion of seven Lapra-Ty absorbable clips (Ethicon Endosurgery, Cincinnati, OH, USA) after redo laparoscopic pyeloplasty (19). The patient required endoscopic removal of the eroded Lapra-Ty clips one month postoperatively. The patient developed a recurrent ureteropelvic junction obstruction and required an open calicostomy. Kurz et al. described a case of a 38-year-old man who developed erosion of Hem-o-Lok clips (Teleflex Medical, Research Triangle Park, NC, USA) 18 years after open right pyeloplasty (23). The encrustation of these clips was removed with a holmium laser, and the clip was removed with a basket. Five months later, the patient developed recurrent flank pain, and subsequent ureteroscopy revealed erosion of suture material through the lumen of the proximal ureter. The suture fragment was endoscopically removed with a basket.

Additionally, 2/9 (22%) case reports required multiple endoscopic procedures. Shrivastava et al. report a case of a 69-year-old man who developed clip erosion three years after laparoscopic left partial nephrectomy for angiomyolipoma (4). The patient underwent endoscopy, and two Hem-o-lok clips were removed. However, six months later, the patient presented with frequency, nocturia, dysuria, and two more Hem-o-lok clips were endoscopically removed. This re-operation mirrors the case described by Kurz et al.

Within the literature, 1/9 (11%) cases involved clips that eroded within the ureteral wall, rather than eroding completing within the lumen of the ureter. Kurz et al. report that the encrusted metal surgical clip was embedded in the wall of the ureter. Clips that are removed from the ureteral wall may also cause ureteral inflammation and scarring, leading to future stricture formation. In our series, 6/6 (100%) of patients had clips embedded within the ureteral wall.

One significant limitation of the existing literature is the lack of follow up after management of ureteral clip erosion. Only 3/9 (33%) reports describe any follow up [15 months (3), 3 months (4), 3 months (14)], which significantly limits our ability to characterize the effectiveness of endoscopic management of ureteral clip erosion.

In our series, all ureteral clip erosions resulted in obstruction, and all clips were embedded within the wall of the ureter. We did not manage our patients endoscopically given our concerns for persistence of ureteral stricture disease and that endoscopic removal may result in a large ureteral defect with subsequent urinary extravasation. As such, we performed reconstructive surgery to manage all ureteral clip erosions. In our series, we noted that all patients had surgical success without recurrence of symptoms of ureteral clip erosion or ureteral obstruction at a median follow up of 14.8 months (IQR, 10.1–18.7). Also, given that our patients had no intraoperative or postoperative complications, and short length of stay, our results suggest this is a safe and effective treatment option for this rare complication.

Our surgical technique was dependent on assessment of the degree of ureteral involvement from the ureteral clip. When patients had <80% of affected ureteral circumference, we favored a non-transecting technique in which we utilized a BMG to perform an onlay-type repair. This technique was utilized as it avoids the need for complete circumferential dissection and minimizes disruption to the peri-ureteral blood supply (31). In our series, there were three patients with proximal ureteral strictures secondary to ureteral clip erosion that involved <80% of the ureteral circumference. In all three cases, we performed a robotic BMG onlay ureteroplasty. We believe that our technique would be applicable for clip erosion with <80% ureteral circumference involvement in the proximal, middle, and distal ureter as long as the erosion did not involve the ureteral orifice. However, when patients had ≥80% affected circumference, there was inadequate ureteral plate to perform a non-transecting repair. In such cases, we performed a transecting repair to ensure adequate robust tissue for reconstruction. This involved an excision and primary anastomosis type repair with adjunctive maneuvers to facilitate a tension free anastomosis. In our series, there were two patients with middle ureteral strictures secondary to ureteral clip erosion that involved >80% of the ureteral circumference. In both cases, we performed a robotic ureteral reimplantation with psoas hitch, and Boari flap.

It is noteworthy that all patients in our series had non-absorbable clip erosion secondary to a previous urologic surgery. Five (83%) of patients originally underwent a reconstructive surgery (i.e., four with a prior pyeloplasty for a ureteropelvic junction obstruction and one with a prior nephroureterectomy for recurrent infections). Although clip migration is a rare complication, we strongly believe that urologists should exercise extreme caution when placing clips near the ureter given the risk of clip erosion. We suggest avoiding the use of permanent clips altogether and utilizing electrocautery and suture ligation as alternative options. When clips are necessary to use close in proximity to the upper tracts, we suggest interposing an omental/retroperitoneal/peri-nephric fat flap between the clip and the upper tracts. Additionally, our results suggest that clip erosion is generally diagnosed in a delayed setting, as the median time to diagnosis was 90.5 months (IQR, 48.4–219.1). This is consistent with the current body of literature, with a median time to diagnosis of 24 months (IQR, 18–30) (3,4,11-15,19,23). Although our series all involved patients who had permanent clip erosion, the literature suggests that clip erosion can occur with both non-absorbable (3,19) and absorbable (4,11-15,23) clips.

Our experience was limited by a small cohort, which may explain our lack of major (Clavien >2) complications. However, as clip erosion into the ureter is rare, generating a large, single-institutional series is difficult. Indeed, prior reports have only documented single case reports of this rare complication. Furthermore, our patients were managed with RUR, which contrasts with the literature that exclusively describes endoscopic management. Our decision to favor surgical resection over endoscopic treatments was largely due to the presence of obstruction, and concern for causing a ureteral perforation/urinoma after clip removal. Given the small number of patients in our cohort and the existing literature, and the heterogeneity of the patient presentations, comparisons between the two treatment modalities cannot be made at this time. Lastly, the duration of follow-up for our series can be considered relatively short compared to larger populations of patients who underwent RUR (26,32). However, compared to existing literature on clip erosions, our follow-up range extends well beyond previously described case reports. Additional follow-up will be performed to quantify the durability of RUR for ureteral obstruction secondary to clip erosion. Such data may add to the foundation of literature and potentially guide future specialty society guideline recommendations. In addition, future studies may benefit by testing the composition of various surgical clips to better characterize potential tendencies for particular polymers to precipitate a foreign body reaction and clip erosions.

Conclusions

Complications stemming from non-absorbable clip erosion into the ureter are generally diagnosed in a delayed fashion. Patients with ureteral obstruction secondary to clip erosion may be managed with RUR with low perioperative morbidity and excellent outcomes. Multi-institutional series with larger sample sizes are still needed to better understand prognosis and long-term outcomes.

Acknowledgments

The abstract of this article has been presented at the American Urological Association Annual Meeting 2024 and the North American Robotic Urology Symposium 2024.

Footnote

Reporting Checklist: The authors have completed the AME Case Series reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-24-485/rc

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-24-485/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-24-485/coif). Z.L. is a consultant for Boston Scientific and Intuitive Surgical and has received grants from Intuitive and Kerecis. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Publication of this case report and accompanying images was waived from patient consent according to the Northwestern University institutional review board (No. STU00216708).

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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