Minimally Invasive Surgical Therapies for Ureteral Polyps: A Systematic Review

Abstract

Background:

Ureteral polyps are rare benign ureteral tumor. No guideline recommends that open or minimally invasive surgery is best for treating ureteral polyps. This article aims to provide a comprehensive review of the minimally invasive techniques currently available for treating ureteral polyps.

Materials and Methods:

We performed a comprehensive search of articles published in PubMed, using the keywords “ureteral” and “polyp,” or “polyps.”

Results:

A total of 275 studies were obtained from the literature search but 96 articles were excluded.

Conclusions:

Several minimally invasive approaches were developed with the advancement of medical technology, including endoscopic, laparoscopic, and robotic approaches; however, the best surgical technique was yet to be decided. Due to the advantages and disadvantages of these approaches, the best surgical approach should be tailored to each patient's needs and the surgeon's preferences and experience.

Introduction

Ureteral polyps are rare benign tumor of the ureter. Ureteral polyps can be divided into primary fibroepithelial and inflammatory polyps secondary to ureteral calculi. No consensus exists about the cause of ureteral fibroepithelial polyps. Numerous causes have been suggested, including obstructions, infections, traumas, chronic irritations, hormonal imbalances, and developmental defects.¹

Patients with obstructive hydronephrosis and renal infection commonly have hematuria and flank pain. When ureteral polyps obstruct the urinary system and cause hydronephrosis, kidney function is impaired.^2,3 Consequently, the goal of any treatment in cases of ureteral polyps is to preserve kidney function. Before minimally invasive techniques, open surgery was the mainstay of treating ureteral polyps. With developments in medical technology, minimally invasive urological surgery has replaced open surgery. No guideline recommends that open or minimally invasive surgery is best for treating ureteral polyps. This article aims to provide a comprehensive review of the minimally invasive techniques currently available for treating ureteral polyps.

Materials and Methods

To verify all available studies, a comprehensive search on minimally invasive surgical therapies for ureteral polyps was carried out according to the Synthesis Without Meta-analysis (SWiM) guidelines. We performed a comprehensive search of articles published in PubMed and included all articles, using the keywords “ureteral” and “polyp” or “polyps.” Two independent reviewers were asked to perform the literature search and review of the articles, and the last search was performed on October 2023. Studies involving animals, meta-analyses, congress abstracts, and non-English articles were excluded.

Results

A total of 275 studies were obtained from the literature search, but 96 articles were excluded: 4 not fitting title/abstract, 3 involving animals, 3 reviews/meta-analyses, and 86 no full text available.

Discussion

Ureteral polyps management: a brief historical review

Due to the limitations of diagnostic techniques in the past, many patients develop severe hydronephrosis or even kidney failure to be diagnosed. Debruyne et al. reported that unnecessary nephroureterectomies were performed in 41 (37%) of 112 cases of fibroepithelial polyps.³ With diagnostic techniques development, several intriguing avenues are emerging that may eventually aid in the ureteral polyp diagnosis, including ultrasonography, conventional radiography, intravenous urography, retrograde pyelography, computed tomography urography (CTU), and magnetic resonance urography.⁴ The emergence of endoscopes, like cystoscopy and ureteroscopy, has also improved the diagnostic level of ureteral polyps.⁴ In the 1960s, pyeloplasty and ureteral segmental resection began to be applied in ureteral polyps with renal function cases. Laparoscopy and robotic platforms have been used for complex surgeries as minimally invasive techniques have evolved.

Minimal invasive treatment in ureteral polyps

Endoscopic surgery

According to the report from Japanese experts in 1965, endoscopic ureteral polyp ectomy was the first minimally invasive surgery in 1949. According to the report, all three cases were polyps in the lower ureter, with a length of 0.5–3 cm, which was removed through cystoscopy. One case had ureteral bladder replantation and partial cystectomy, but there was no follow-up on the treatment effectiveness.⁵

The first ureteroscopy for ureteral polyp surgery was reported by Italian scholars in 1986.⁶ However, due to the inability to find complete literature, it is not possible to analyze the complications and clinical effects that occur when ureteroscopy is first applied. Ureteroscopy is widely used to diagnose and biopsy ureteral polyps now.⁷ Together, ureteroscopy is gradually being used for polyps' removal.^8–11 During minimally invasive treatment of ureteral lesions, grasping forceps, baskets, laser fibers, and cautery instruments can be introduced, facilitating accurate diagnosis and definitive. However, before 2000, there was no specific description of how to remove ureteral polyps under ureteroscopy. We believe forceps can easily rip ureteral mucosa when removing polyps.

In recent years, many reports have been on holmium yttrium-aluminum-garnet (Ho-YAG) laser in endoscopic ureteral polypectomy for ureteral polyps.^4,12–15 The first application of the Ho-YAG laser in endoscopic ureteral polypectomy was reported by Yagi et al. in 2001. Ho-YAG laser at 2 watts and 6 Hz was used to incise the middle ureter tumor base using a 400 mm fiber set. The tumor base was partially ablated to avoid ureteral perforation, and a Double-J stent was inserted. The follow-up postoperative excretory urography did not reveal right hydronephrosis.¹⁵

Endoscopic treatment of ureteral polyps is preferable due to its low invasiveness, fewer complications, and shorter surgical time and hospital stay. According to reports, this surgery is particularly useful for solitary ureteral polyps. Moreover, multiple ureteral polyps have also been treated with ureteroscopic Ho-YAG laser resection. For managing these polyps, the Ho-YAG laser is an excellent option. Silica fibers with a diameter of 200 to 365 nm can be inserted through the working ports of 7F and 9F flexible ureteroscopes. The thermal injury depth to the tissue in contact with laser activation is 0.5 to 1 mm, which reduces the possibility of deep thermal injury to tissue.^16,17 Perforation is unlikely if the fiber tip is more than 1 mm from the ureteral wall.¹⁸

For patients with polyps, calculi, or ureteral strictures, the Ho-YAG laser can also be used for lithotripsy and ureterotomy.¹⁹ According to some scholars, Ho-YAG laser treatment of multiple polyps is prone to ureteral stenosis due to laser burning. Six cases of single polyps larger than 5 cm were reported at Renji Hospital of Shanghai Jiao Tong University. After undergoing antegrade and retrograde endoscopic laser resection, 1 patient developed ureteral stenosis during a 3-month follow-up.²⁰ In the study of Childs et al., 12 (55%, 12/22) patients underwent endoscopic treatment, and 11 of them were successful. Three patients with ureteral stricture and one with incomplete polyp resection required open surgery after endoscopic treatment. A ureteroscopy successfully treated 1 patient (1/12) with a recurrence of ureteral polyps at 26 months. To detect ureteral strictures or recurrences early, postoperative surveillance is recommended.²¹ A case of a mid-pregnancy woman with ureteral polyps who underwent endoscopic Ho-YAG laser resection was reported with no complications or recurrence. This confirms Ho-YAG laser safety.²²

With increasing laser types, more lasers are used for ureteroscopic ureteral polypectomy. According to Sheng et al., 25 cases of ureteral polyps were resected using Ho-YAG lasers (12 cases) or thulium lasers (13 cases). The Ho-YAG laser group had three ureteral perforation cases during surgery and four postoperative ureterostenosis cases. During the procedure, none of the patients in the thulium laser group experienced severe complications. Additionally, the thulium laser group did not develop ureterostenosis or recurrence of the condition.²³ Multiple ureteral fibroepithelial polyps were successfully treated using the thulium laser in a pediatric patient were reported.²⁴ A total of 21 adult patients with ureteral fibroepithelial polyps performed ureteroscopy operations and resected the polyps with a thulium laser. Notably, no patient exhibited ureteral perforation. During the follow-up period, ultrasonography or CTU revealed favorable recovery without recurrence or ureterostenosis.

Ureteroscopic thulium laser resection is a minimally invasive and effective method for treating ureteral fibroepithelial polyps.²⁵ Although Ho-YAG and thulium laser resection are effective methods for treating ureteral polyps, the latter reduces the ureterostenosis risk.²³ Diode laser was first used in 2015 and monitored for 5 months without recurrence, although fewer people used it, and no more reports exist.²⁶

Whether the polyps secondary to the ureteral stones need to be actively treated? Among the polyps associated with stones, Kara only underwent a biopsy without further resection but instead chose observation. The polyps in these patients did not grow or exhibit any symptoms during the follow-up period.²⁷ Cho et al. found 14 fibroepithelial and 21 inflammatory polyps in 35 followed-up individuals. Nine patients with fibroepithelial polyps were among the 20 patients who underwent ureteroscopy based on follow-up. Postoperative ureteral stricture and moderate-to-severe hydronephrosis are linked to the number of resected polyps regardless of type. Treatment of adjacent ureter stones may leave polyps in the ureter. Hasty resections of polyps may increase the ureteral stricture risk.²⁸

Laparoscopic surgery

Laparoscopic surgery is mainly used for multiple ureteral polyps.^29,30 For single large polyps, laparoscopic surgery³¹ or endoscopic surgery can be chosen.³² There is no research comparing the pros and cons of the two methods. Despite cases of laser, resection of multiple polyps in one side of the ureter under ureteroscopy has been reported.³³ However, laparoscopic surgery is recommended for multiple polyps.^34,35 The surgical procedure was designed following the location and size of polyps, including segmental ureterectomy of polyps + pyeloureterostomy, segmental ureterectomy of polyps + ureter − ureteral anastomosis.

The first laparoscopic treatment of ureteral polyps was retroperitoneal pyeloplasty, reported by Satoru Kawakami in 2003.³⁶ Retroperitoneal or transperitoneal laparoscopic pyeloplasty can be performed depending on the surgeon's preferences and experience.^31,37,38 There is currently no evidence to suggest significant differences in operational time and overall success rate between these two methods. Compared to endoscopy, the advantage of laparoscopic surgery is that it can remove the base of the tumor and reduce ureteral stenosis caused by laser thermal injury.

Children with ureteral polyps can also benefit from laparoscopic pyeloplasty.^35,38–41 However, it is safe, effective, and minimally invasive to remove multiple ureteral polyps in pediatric patients by laparoscopy. Seven cases of pediatric ureteral polyps reported by Qilu Hospital of Shandong University were treated with laparoscopic surgery; hydronephrosis was alleviated in comparison with before surgery, and no recurrence of polyps was reported after surgery.⁴⁰ Seven cases of ureteral polyps had laparoscopic pyeloureteroplasty at Anhui Provincial Children's Hospital from 2017 to 2020. During postoperative follow-ups ranging from 1 to 30 months, the patient recovered satisfactorily, and hydronephrosis was relieved.⁴¹

Laparoscopy is an effective treatment measure, but the positioning of polyps is crucial for laparoscopic surgery. Due to incorrect positioning, excessive removal of normal ureters or incomplete removal of polyps may occur. Xia proposed a transabdominal laparoscopic ureteroureterostomy using intraoperative retrograde ureteroscopy. Following establishing a minimally invasive working channel, we carefully dissected the ureter by laparoscopy and introduced a rigid ureteroscope for guidance before pushing it to the obstruction site. Dimming the laparoscopic light source revealed the ureteroscopy light source well under the laparoscope. Consequently, the surgeon could identify ureteral polyps accurately with the rigid ureteroscope and laparoscope simultaneously.⁴² The same surgical method was also reported in 2016.⁴³

Robotic surgery

The application of robotic surgery in treating ureteral polyps was first reported in 2006. Osbun et al. discovered mean postoperative length of stay was 1.5 days. The symptoms and severity of hydronephrosis have improved in 3 patients observed for at least 1 year.⁴⁴ Cattaneo et al. also removed a huge ureteral polyp through robotic surgery.⁴⁵ Robot-assisted laparoscopy is a safe and effective alternative to endoscopic surgery for treating fibroepithelial ureteral polyps. It may be preferable to use the robotic platform if there are large or multifocal ureteral polyps or a concomitant narrowing of the ureteropelvic junction. More robots are being applied to the surgery of ureteral polyps.^46,47

The first robotic system used in laparoscopic surgery was Da Vinci. The Single Port system, which allowed the robotic arm to rotate 360° around the cannula, raised even more interest.⁴⁸ Surgical precision and extended maneuverability with the robotic system facilitated better dissection, reducing blood loss and increasing suture quality. Moreover, robotic pyeloplasty was effective in children who underwent secondary pyeloplasty and complex procedures, with a success rate of 94% to 100%.⁴⁹ Comparing robotic surgery to conventional open pyeloplasty, the only disadvantage was the higher cost. It should be noted, however, that robotic pyeloplasty may be preferable due to its shorter hospital stay, which could offset its high costs.

Because of its shorter learning curve, robotic pyeloplasty was particularly appealing. This is very useful for surgeons new to standard laparoscopic pyeloplasty.^50,51 According to a report, many surgeons prefer robotic pyeloplasty because it is less complicated, reduces tremors, and provides better ergonomics than laparoscopy.⁵² Compared to laparoscopic surgery, robotic surgery had 79 minutes for anastomosis compared to 105.5 minutes for laparoscopic surgery with a comparable success rate (96.7% versus 100%, respectively).⁵³ Both modalities showed similar results, according to Zhang et al. who studied the operative time and mean hospital stay. According to the authors, both groups had comparable parameters, including success rate.⁵⁴ According to Hong et al. robotic surgery is much faster than laparoscopic surgery. This study was conducted at two different centers with different surgical teams, which may explain its results.⁵⁵

Conclusion

Although surgery has a high success rate, not all cases of ureteral polyps require surgical intervention. Understanding ureteral polyps' natural course and progression and developing surgical methods according to the patient's situation is necessary. Due to the advantages and disadvantages of these approaches, the best surgical approach should be tailored to each patient's needs and the surgeon's preferences and experience.

Footnotes

Acknowledgment

We would like to thank all the authors in this study. We acknowledge the contribution of the participants. We thank Home for Researchers editorial team () for language editing service.

Authors' Contributions

B.C.: Writing–original draft (lead); L.X.: Data curation (lead); Y.F.: Writing–review and editing (equal); L.Z.: Writing–review and editing (equal); J.S.: Conceptualization (lead) and funding acquisition (lead); J.H.: Methodology (lead) and supervision (lead).

Data Availability Statement

A data availability statement is not applicable because this study is based exclusively on published literature.

Statement of Ethics

An ethics statement is not applicable because this study is based exclusively on published literature. The approval and written informed consent were not required because this study is based exclusively on published literature.

Disclosure Statement

No competing financial interests exist.

Funding Information

This study protocol was reviewed and approved by the Science and Technology Commission of Hangzhou Municipality, Zhejiang Province, China (Grant Number: 20191231Y166).

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