Minimally Invasive Surgeries in the Management of Renal Parapelvic Cysts: A Retrospective Comparative Study Hualin Chen1, Yang Pan1, Xiaoxiang Jin1, Gang Chen1* Purpose: To compare the efficiency and safety of two minimally invasive surgeries, laparoscopy and flexible ureteroscopy (fURS), in the management of renal parapelvic cysts. Materials and Methods: Between January 2013 and April 2019, patients who suffered from parapelvic cysts and received fURS or laparoscopy at our hospital were recruited for this study. All patients underwent biopsies of the cyst wall. Primary outcome was treatment success, which was defined as symptomatic and radiological. During follow-up, telephone contact and CT scans were used to record any relevant symptoms and any recurrence, respec- tively. Results: A total of 33 patients (22 in fURS; 11 in laparoscopy) were included in this study. Flank pain prior to the procedures were reported by 14/22 patients and 6/11 in fURS and laparoscopy, respectively (P = .62), and patients had complete pain relief after the operation. The complication rate was significantly lower in the fURS group than in the laparoscopy group (P = .01). Minor complications were observed in 3/22 and 5/11 patients (Grade 1 and 2) in the fURS and laparoscopy group, respectively. All patients were controlled by conservative treatment. Howev- er, 1/11 major complication (Grade 3b) was detected in the laparoscopy group and managed by ureteroscopy to remove the obstruction under general anesthesia. Significant differences were found in operative time (P = .01) and postoperative hospital stay (P = .01), while medical expenses were similar between the two groups (P = .42). During follow-up, no recurrence was detected in CT scans. Conclusion: In the management of parapelvic cysts, two minimally invasive surgeries were comparable in effi- ciency. However, fURS was superior to laparoscopic unroofing with regard to the complication rate, operative time, and postoperative hospital stay. Keywords: laparoscopy; parapelvic cyst; ureterorenoscopy INTRODUCTION Renal cysts are common with a prevalence of 5%. Most renal cysts are asymptomatic and a benign disease in regard to the Bosniak Classification. Thus, non-conservative treatment is not necessary for such cysts.(1) However, renal parapelvic cysts, accounting for a small part of renal cysts, may be accompanied by symptoms such as lumbago, hematuria, and infection.(2) Moreover, it not only represents a diagnostic challenge due to its rarity and misdiagnosis as hydronephrosis by imaging,(3) but also leads to treatment difficulties due to its complexity and proximity to the renal hilum.(4) In the past decades, multiple minimally invasive treat- ment options including sclerotherapy, percutaneous aspiration, and laparoscopic unroofing have been ex- plored by urologists.(5) For sclerotherapy, the potential risk factor is sclerosing agent extravasation into the re- troperitoneum. As a result, severe perinephric inflam- mation, abscess or ureteropelvic junction obstruction (UPJO) may develop. Moreover, aspiration is associat- ed with a relatively high recurrence rate. Laparoscopic unroofing remains the most advantageous technique for the management of this disease, especially in com- plicated cases.(6) More recently, internal drainage by flexible ureteroscopy (fURS) has been reported as an effective, feasible, and safe treatment option for par- apelvic cysts.(7) However, there have been no studies comparing the efficacy and safety of the two minimally invasive surgeries, laparoscopic unroofing and fURS in the management of parapelvic cysts. Thus, we per- formed a cohort study to address this topic based on our single-center experience. MATERIALS AND METHODS Patients With the approval of the First Affiliated Hospital of Chongqing Medical University Research Ethics Com- mittee (Chongqing, China), we retrospectively re- viewed all patients suffering from renal parapelvic cysts between January 2013 and April 2019 at our hospital. Written informed consent was obtained from all pa- tients. The inclusion criteria were: (1) patients with symp- toms such as flank pain, infection and/or hematuria, Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China. *Correspondence: Department of Urology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China. Tel: +86-13668039053, Fax: +86-23-89012919, Email: chengang2308@163.com. Received September 2020 & Accepted January 2021 ENDOUROLOGY AND STONE DISEASE Urology Journal/Vol 18 No. 4/ July-August 2021/ pp. 389-394. [DOI: 10.22037/uj.v16i7.6466] (2) asymptomatic patients with large cysts which com- pressed the collecting system and caused urinary ob- struction and hydronephrosis, which was described in a prior study in detail(7),(3) patients treated with fURS or laparoscopy. All patients received preoperative com- puted tomography (CT) scans and intravenous urogram (IVU) to identify the characteristics of the parapelvic cysts (Figure 1). Patients whose cysts were suspected of malignancy in CT scans or patients with cardiopul- monary insufficiency or coagulation disorders or ure- teral stricture history were excluded from this study. Surgical procedures Based on our experience and published literature, there are three subtypes of parapelvic cyst, including exoge- nous, mixed, and endogenous.(8) The classification was defined by the topographical relationship between cyst and the renal surface and the pelvis. The treatment mo- dality, fURS or laparoscopy, was decided by active dis- cussion with patients, regardless of the subtype of the cysts. Two surgeons with more than five-year surgical experi- ence performed one type of operation each. In the fURS group, patients were given general anesthe- sia and were placed in the lithotomy position. An 8-Fr fURS was inserted into the renal pelvis and the cyst wall (with typical characteristics, such as thin wall, pale blue membrane) could be observed. Once the wall was identified, a 200-μm Holmium Laser fiber was adopt- ed to incise the wall and coagulate the incision mar- gin. Subsequently, the inner cyst wall was examined to avoid the misdiagnosis of cystic renal cell carcinoma. If there was any partition in the cyst, it was cut with the laser to avoid recurrence. Then, a 6-Fr ureteral stent, which was removed one month post operation, was rou- tinely placed with the proximal end inside the cyst to drain the cystic fluid. In the laparoscopic group, patients were given general anesthesia and were placed in the lateral decubitus posi- tion. The retroperitoneal approach was performed in all patients. Primarily, three ports were placed as the way reported in a previous study.(9) With careful dissection, the parapelvic cyst was identified and then the cyst wall was incised with an ultrasonic scalpel and the cystic fluid was aspirated. Then, the incision margin was co- agulated with ultrasonic scalpel and the placement of a drainage tube and the wounds were sutured. Ureteroscopic and laparoscopic biopsies were per- formed in all patients, and the specimens were sent for further pathological examination. Baseline characteristics and outcomes Baseline characteristics and outcome measurements were retrieved from the electronic medical record sys- tem. The former included gender, age, body mass index (BMI), size/side of cysts, and number of patients with symptoms. The size of cyst was measured by using its longest axis in the CT scans. Outcomes were classified into primary and secondary. The primary outcome was defined as treatment success, which included sympto- matic and radiological success. Symptomatic success was defined as complete postoperative pain relief, and radiological success was defined as a decrease in cyst size by more than half of its previous size according to CT scans performed during follow up. Pre- and postoperative flank pain intensity of patients were quantitatively evaluated by a 10-point visual analog scale ranging from 0 (no pain) to 10 (severest pain). Meanwhile, pain was classified into three grades according to the score: slight (0-3), moderate (4-6), and severe (over 6). Patient with a pain score > 3, or with a residual pain rating, was regarded as symptomatic fail- ure. The others were categorized as having symptomat- ic success. Secondary outcomes were regarded as operative time, length of hospitalization, complications, and medical expenses. Complications were classified into minor (Grade 2 or lower) and major (Grade 3a or higher) ac- cording to the Clavien-Dindo Classification.(10) The patients were followed up by telephone after dis- charge to record any symptom related to parapelvic cyst. On August 31, 2019, the deadline of our study, all patients were advised to have CT scans performed to detect any recurrences. Statistical analyses Chi-square test was performed to analyze dichotomous variables. For continuous variables, Shapiro-Wilk test was carried to analyze data for normality. We noticed that most continuous variables were not subject to a normal Gaussian distribution. Hence, non-parametric Mann-Whitney U test was used for the analysis of con- tinuous variables. SPSS 22.0 was used to perform the statistical analyses. Two-tailed P < .05 were considered statistically significant. RESULTS In total, 33 consecutive patients (22 in fURS group and 11 in laparoscopic group) were included in the study. Overall, more than 50% of patients presented with flank pain (63.6% vs. 54.5%, P = .62) and others had their parapelvic cysts revealed incidentally. There was no significant difference between the two groups with re- spect to age (P = .32), BMI (P = .91), gender (P = .11), cyst size (P = .10), laterality of cyst (P = .80). Table 1 summarizes the demographics and baseline characteris- Laparoscopy and ureterorenoscopy in renal parapelvic cyst-Chen et al. Table 1. Demographics and baseline characteristics of the patients. Characteristic fURS (N=22) Laparoscopy (N=11) P-value a Age, year 54.0 (45.0 - 63.0) 58.0 (53.0 - 64.0) .32 Gender, Male (%) 12 (54.6%) 6 (75. 0%) .11 BMI 24.1 (21.8 - 26.5) 23.5 (23.3 - 25.0) .91 Flank pain (%) 14 (63.6%) 6 (54.5%) .62 Cyst Size, mm 5.6 (4.8 - 7.0) 4.9 (4.0 - 5.8) .10 Laterality, L (%) 15 (68.2%) 5 (62.5%) .80 Abbreviations: BMI, body mass index. Values are presented as median (IQR) or number (percent). a Categorical variables were compared by Chi-square test. Vol 18 No 4 July-August 2021 390 Endourology and Stones diseases 391 tics of the participating patients. In the fURS group, one patient suffered from parapelvic cyst in the solitary kidney, and the renal function did not deteriorate after the procedure. One carried bilat- eral parapelvic cysts (right: 2.52 cm; left: 5.8 cm), and cyst at left side was managed (Supplementary Figure 1). The cyst of one case was difficult to be found with direct vision of fURS alone. And around 2 ml methyl- ene blue was injected into the cyst through percutane- ous approach to dye the fluid. Then, the cyst wall was located and incised successfully. One concomitant with ipsilateral large simple renal cyst (8 cm at diameter) was treated with laparoscopic unroofing simultaneously (Supplementary Figure 2). Patients in the fURS group had significantly shorter length of operative time and postoperative hospital stay than those in the laparoscopic group (P = .01, P = .01, respectively). The cost of hospitalization was similar between the two groups (P = .42). The complication rate was statistically lower in the fURS group than that in the laparoscopic group (P = .01) (Table 2). There was no intraoperative complica- tion (massive bleeding, transfusion, etc.) recorded in the fURS group. However, two cases (9.09%) of fever (Grade 2) and one (4.55%) case of abdominal discom- fort (Grade 1) were recorded after the procedure, which were managed by intravenous antibiotics and conserva- tive treatment, respectively. In the laparoscopic group, the mean blood loss was 95 ml. Intraoperative massive hemorrhage (ranging from 150 to 400 ml) occurred in 4/11 (36.4%) patients (Grade 1). One-unit blood trans- fusion was required by one (25%) patient (Grade 2). 2/11 (18.2%) patients suffered from persistent postop- erative urine leakage (more than 72 hours). One (50%) patient with fever was controlled by intravenous antibi- otics (Grade 2). Another patient (50%) was suspected to have an obstruction in the ureter and received uret- eroscopy and ureteral stenting under general anesthesia (Grade 3b). All patients had negative pathologic findings in the cyst wall for malignancy. Postoperatively, complete pain re- lief was observed in all patients with lumbago before the operation. During follow up, radiological success was observed in all patients (Figure 2). DISCUSSION This was the first study to compare the efficacy and safety of laparoscopy and fURS in the management of parapelvic cysts. The results revealed that both pro- cedures were efficient. However, patients in the lapa- roscopic group had a statistically higher incidence of complications than those in the fURS group. Moreover, significantly longer operative time and postoperative hospital stay were seen in the laparoscopic group. Through published studies investigating the treatment of parapelvic cysts, we noticed that most studies with a sample size of more than 10 cases were conducted in China,(1,2,9,11-21) while in western countries, most studies were case reports. Firstly, the population of Chinese studies was larger than that in western countries, indi- cating that more patients suffered from parapelvic cyst even though its rate of occurrence is rare. Secondly, urologists in western countries performed surgery for symptomatic cysts, which were a small part of overall parapelvic cysts. While for asymptomatic cysts, active follow-up was recommended.(14-16,19-21) In China, ac- Table 2. Outcome measures Outcomes fURS (N=22) Laparoscopy (N=11) P-value a Treatment success 22 11 Operative time, min 45.0 (28.8-56.3) 80.0 (70.0-95.0) .01 Postoperative hospital stay, day 2.0 (1.8-3.0) 4.0 (3.0-7.0) .01 Hospitalization expense, CNY 37491.6 (20302.7-63842.8) 27293.5 (19495.3-46307.6) .42 Pain score Preoperation 5 (1-9) 6 (2-8) .45 Postoperation 1 (1-2) 2 (1-3) .37 Complications .01 <= Grade 2 3 (13.6%) 5 (45.5%) >= Grade 3a 0 1 (9.1%) F/u, mon 42.5 (20.5 - 53.5) 19.0 (9.0 - 55.0) .21 Abbreviations: F/u, follow up. CNY, Chinese Yuan. Values are presented as median (IQR) or number (percent). a Categorical variable was compared by Chi-square test. P values in Bold indicate significant results. Figure 1. IVU demonstrated that the parapelvic cyst (arrow) com- pressed the collecting system and no contrast media entered the cyst. Laparoscopy and ureterorenoscopy in renal parapelvic cyst-Chen et al. cording to the recommendations of Chinese Urology Association (CUA) Guidelines in 2014 and the latest edition of Wu Jieping Urology in 2019, active manage- ment should be applied for asymptomatic patients with large (cut-off not defined) parapelvic cysts that caused massive normal renal parenchymal reduction, hydrone- phrosis, and/or urinary obstruction. Additionally, Wang et al.(7) performed fURS for selective asymptomatic cyst larger than 4 cm, and a study by Mao et al.(17) included asymptomatic patients with a cyst size larger than 3 cm. The cyst sizes in our study ranged from 3.8 cm to 9.5 cm. Treatment success was achieved in all patients in our study. The result revealed that both two minimally in- vasive surgeries were efficient, and our result was con- formant with previous studies.(1,2,9,11-13,17,18) However, the sample size was relatively small with weak statistical power, and the duration of the follow-up period may not be sufficient. The complication morbidity favored fURS. Overall, most intra- and post-operative complications were mi- nor (Grade 2 or lower) and could be managed by con- servative treatment. The only single major complication (Grade 3b) occurred in the laparoscopic group. The pa- tient developed persistent urine leakage, caused by a suspected obstruction in the ureter. Thus, 5 days post laparoscopy, ureteroscopy and ureteral stent placement were performed with the patient under general anesthe- sia. During the procedure, calculus was discovered at the site of ureteropelvic junction and was pushed back into the pelvis with a ureteral stent. Considering that the patient was suffering urine leakage and multiple kidney stones, lithotripsy was not performed. 36.4% of patients in the laparoscopic group developed intraoperative massive hemorrhage (blood loss amount over 100 ml). Moreover, a single patient (25%) required blood transfusion. This may be due to the following: (1) two cysts were relatively large with sizes of 8.9 cm and 6.8 cm and(2) a further two cysts were strongly attached to the surrounding tissue, inducing extensive dissection and causing blood seepage. Bleeding events may appear more serious compared with those reported in previous studies. However, the mean blood loss in our study was 95 ml, which is comparable to that in other studies.(15) No large number of hemorrhages were reported in the fURS group. Although the incision in the cyst in the fURS group was performed blind, we adopted follow- ing key-steps to avoid hemorrhaging. First, the incision site was performed away from the renal calyceal and was at the most bulging site of the cyst. Second, we per- formed the incision into the wall with an initial diame- ter of 0.5 cm, and the incision was broadened once the cyst was identified. Third, the incision did not exceed the cyst-pelvic junction. Demonstrated by the result in this study, patients in the fURS group had a significantly shorter operation time and more rapid postoperative recovery compared to those in the laparoscopy group. However, in the lap- aroscopic approach, the surgeon had to place trocars (usually 3) and carefully dissect before the surgeon was able to incise the cyst wall, while the fURS surgeon had direct access to the cyst wall through a natural orifice. This led to the advantage of shorter operation and hos- pitalization times. Wang et al. reported their experienc- es in further shortening the operation time by modifying the fURS procedure.(7) However, it is important to remember that the fURS could not always identify the parapelvic cysts with untypical features (thick wall, ill-defined border, etc.). One cyst in our study was not identified using a uretero- scope alone. A modified procedure with methylene blue injection, which was reported in a previous study,(7) was adopted to dye the cystic fluid. Although the cyst was successfully discovered and excised, the procedure took over two hours (median operative time was 45 minutes in fURS group) to complete all the steps (re-steriliza- tion, re-position, puncture and re-fURS). Kang et al. and Wang et al. studied the modified strategy for locat- ing the cyst and found that cysts with typical character- istics could be located with a ureteroscope alone, while those without, required multiple auxiliary procedures to help localization. Disappointingly, we could not distin- guish the two kinds of cysts by preoperative CT scans or IVU alone, suggesting that identification of the kind of cyst requires modified procedures and complicated techniques, which were unknown before the operation. Thus, an evaluation system is required to avoid unnec- essary punctures and complicated procedures. This study had several limitations. First, a small sample size with a retrospective nature was the main drawback, which may have resulted in potential selection bias. However, as one of the largest teaching hospitals in the southwest of China, our hospital patient number was large, and many patients from surrounding cities sought medical attention, indicating that the selection bias might be minimized. Second, renogram was not ap- plied to demonstrated urinary obstruction. Third, even though no massive hemorrhage was reported in the lit- Figure 2. The CT imaging of one parapelvic cyst in the fURS group before surgery (A) and 22 months after surgery (B). Laparoscopy and ureterorenoscopy in renal parapelvic cyst-Chen et al. Vol 18 No 4 July-August 2021 392 Endourology and Stones diseases 393 erature for patients undergoing fURS, we must keep in mind that the incision of the cyst wall was blindly per- formed and a CT angiogram or endoluminal Doppler ultrasound should have been performed to avoid vessels in the common wall. In the future, well-designed, multi- ple-center studies with large sample size are required to further validate our findings. CONCLUSIONS To the best of our knowledge, this is the first head-to- head comparative study conducted to explore two most commonly used minimally invasive surgeries in uro- logical practice, fURS and laparoscopy, in the manage- ment of renal parapelvic cysts. The results revealed that the two approaches were comparable in regard to the treatment efficiency, while the complication rate, oper- ative duration, and length of postoperative hospital stay, favored fURS. However, it should be noted that fURS could not be used for the treatment of cortical cysts and the power of our study was not strong. For patients with parapelvic cysts, our initial experience could be applied in future decision making on the most applicable surgi- cal technique. ACKNOWLEDGMENT This work was supported by Chongqing Science and Technology Commission (cstc2015shmszx120067). CONFLICTS OF INTEREST The authors report no conflicts of interest APPENDIX https://journals.sbmu.ac.ir/urolj/index.php/uj/libraryFiles/downloadPublic/27 REFERENCES 1. Kang N, Guan X, Song L, Zhang X, Zhang J. Simultaneous treatment of parapelvic renal cysts and stones by flexible ureterorenoscopy with a novel four-step cyst localization strategy. Int Braz J Urol. 2018;44:958-64. 2. Zhao Q, Huang S, Li Q, et al. Treatment of Parapelvic Cyst by Internal Drainage Technology Using Ureteroscope and Holmium Laser. West Indian Med J. 2015;64. 3. Choi HS, Kim CS, Bae EH, Ma SK, Kim SW. Bilateral Parapelvic Cyst Misdiagnosed as Hydronephrosis. Chonnam medical journal. 2019;55:65-. 4. Rossi SH, Koo B, Riddick A, Shah N, Stewart GD. Different successful management strategies for obstructing renal parapelvic cysts. Urologia internationalis. 2018;101:366- 8. 5. Agarwal M, Agrawal MS, Mittal R, Sachan V. A randomized study of aspiration and sclerotherapy versus laparoscopic deroofing in management of symptomatic simple renal cysts. J Endourol. 2012;26:561-5. 6. Eissa A, El Sherbiny A, Martorana E, et al. Non-conservative management of simple renal cysts in adults: a comprehensive review of literature. Minerva urologica e nefrologica = The Italian journal of urology and nephrology. 2018;70:179-92. 7. Wang Z, Zeng X, Chen C, Wang T, Chen R, Liu J. Methylene Blue Injection via Percutaneous Renal Cyst Puncture Used in Flexible Ureteroscope for Treatment of Parapelvic Cysts: A Modified Method for Easily Locating Cystic Wall. Urology. 2018. 8. Yu W, Zhang D, He X, et al. Flexible ureteroscopic management of symptomatic renal cystic diseases. The Journal of surgical research. 2015;196:118-23. 9. Chen Z, Chen X, Luo YC, He Y, Li NN, Wu ZH. Retroperitoneoscopic decortication of symptomatic peripelvic renal cysts: Chinese experience. Urology. 2011;78:803-7. 10. Liu T, Peng Y, Jia C, Fang X, Li J, Zhong W. Hepatocyte growth factor-modified adipose tissue-derived stem cells improve erectile function in streptozotocin-induced diabetic rats. Growth Factors. 2015;33:282-9. 11. Yu W, Zhang D, He X, et al. Flexible ureteroscopic management of symptomatic renal cystic diseases. J Surg Res. 2015;196:118- 23. 12. Wang Z, Zeng X, Chen C, Wang T, Chen R, Liu J. Methylene Blue Injection via Percutaneous Renal Cyst Puncture Used in Flexible Ureteroscope for Treatment of Parapelvic Cysts: A Modified Method for Easily Locating Cystic Wall. Urology. 2019;125:243-7. 13. Shao Z-Q, Guo F-F, Yang W-Y, et al. Percutaneous intrarenal marsupialization of symptomatic peripelvic renal cysts: a single- centre experience in China. Scandinavian journal of urology. 2013;47:118-21. 14. Shah JB, Whitman C, Lee M, Gupta M. Water under the bridge: 5-year outcomes after percutaneous ablation of obstructing parapelvic renal cysts. Journal of Endourology. 2007;21:1167-70. 15. Roberts WW, Bluebond-Langner R, Boyle KE, Jarrett TW, Kavoussi LR. Laparoscopic ablation of symptomatic parenchymal and peripelvic renal cysts. Urology. 2001;58:165- 9. 16. Micali S, Pini G, Sighinolfi MC, De Stefani S, Annino F, Bianchi G. Laparoscopic simultaneous treatment of peripelvic renal cysts and stones: case series. J Endourol. 2009;23:1851-6. 17. Mao X, Xu G, Wu H, Xiao J. Ureteroscopic management of asymptomatic and symptomatic simple parapelvic renal cysts. BMC Urol. 2015;15:48. 18. Luo Q, Zhang X, Chen H, et al. Treatment of renal parapelvic cysts with a flexible ureteroscope. Int Urol Nephrol. 2014;46:1903- 8. 19. Doumas K, Skrepetis K, Lykourinas M. Laparoscopic ablation of symptomatic peripelvic renal cysts. J Endourol. 2004;18:45- 8. 20. Camargo A, Cooperberg MR, Ershoff BD, Rubenstein JN, Meng MV, Stoller ML. Laparoscopic management of peripelvic renal cysts: University of California, San Francisco, experience and review of literature. Urology. Laparoscopy and ureterorenoscopy in renal parapelvic cyst-Chen et al. 2005;65:882-7. 21. Basiri A, Hosseini SR, Tousi VN, Sichani MM. Ureteroscopic management of symptomatic, simple parapelvic renal cyst. J Endourol. 2010;24:537-40. Laparoscopy and ureterorenoscopy in renal parapelvic cyst-Chen et al. Vol 18 No 4 July-August 2021 394