Laparoscopic calyceal diverticulectomy: step-by-step surgical technique and clinical experience

Introduction

Renal calyceal diverticulum is a cystic lesion within the kidney containing urine, with the cyst wall lined by transitional cell and surrounded by mucosal muscle layers. The cyst cavity is often connected to the collecting system by a narrow infundibulum (1). The narrow infundibulum of the renal calyceal diverticulum leads to urine retention within the diverticulum, and it may be one of the major causes of diverticular stone formation (2). Among patients with renal calyceal diverticulum, approximately 10–50% have concomitant diverticular stones (3,4). When the diverticular infundibulum is significantly obstructed or when infection is present, patients may experience symptoms such as back pain, fever, or hematuria, often necessitating surgical intervention. Currently, the treatment options for renal calyceal diverticulum with stones include extracorporeal shock wave lithotripsy (ESWL), percutaneous nephroscopy, ureteroscopy, and laparoscopic surgery etc. (5). Among these, laparoscopic surgery is an important surgical approach, especially suitable for patients with diverticula located on the anterior aspect of the kidney, thin overlying parenchyma, or large and complexly branched stones (6). Currently, there is a variety of approaches for laparoscopic removal of renal calyceal diverticulum, and there is no standardized surgical procedure. Here, we report on laparoscopic removal of renal calyceal diverticulum with mucosal excision, aiming to demonstrate the surgical technique of this approach. We present this article in accordance with the SUPER reporting checklist (available at https://aos.amegroups.com/article/view/10.21037/aos-24-2/rc) (7).

Case presentation

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). Written informed consent was obtained from the patient for the publication of this study, and accompanying images and video. A copy of the written consent is available for review by the editorial office of this journal.

The patient is a 38-year-old female who presented with left-sided flank pain accompanied by fever for six months. She had previously sought medical attention at another hospital, where left renal cyst with infection was considered, and she underwent percutaneous drainage and anti-infection. She has now come to our hospital for further evaluation and treatment. No significant medical history was reported, and physical examination revealed no apparent abnormalities. The computerized tomography urography (CTU) revealed a cystic lesion in the left kidney with intracystic high-density shadows, raising considerations for renal cyst calcification or renal calyceal diverticulum concomitant stones. To further clarify the diagnosis, a prone position CT scan was performed, revealing mobile high-density content within the cyst cavity (Figure 1). Renal calyceal diverticulum with concomitant stone was suspected. Subsequently, a laparoscopic renal diverticulectomy and stone removal were performed by an experienced expert in laparoscopic partial nephrectomy. Intraoperatively, a retrograde ureteral stent was placed and methylene blue injection was conducted, confirming the diagnosis of renal calyceal diverticulum and the diverticular orifice. The diverticular mucosal was completely dissected and the diverticular orifice was closed which confirmed by another methylene blue injection. The warm ischemic time was 28 min. The patient recovered well without complications such as bleeding or urinary fistula, and renal function was normal. After surgery, the creatinine was 55 µmol/L, and the hemoglobin level was slightly decreased (101 to 95 g/L). Regular follow-up has shown no recurrence of diverticulum or stones after six months.

Figure 1 Computed tomography images of kidneys show movable high-density content within the cyst cavity. (A) Supine position computed tomography. (B) Prone position computed tomography.

Surgical techniques

We performed calyceal diverticulectomy by retroperitoneal laparoscopic approach. Under general anesthesia, the patient was positioned in the lithotomy position and an open-ended ureteral catheter was placed. And then, the patient was changed to the right lateral decubitus position. After disinfecting and laying the towel, we established 4 trocar ports and performed the surgery in the following 10 steps.

Step 1: clean the extraperitoneal fat and show the perirenal fascia.

Step 2: incise the perirenal fascia and expose the psoas major muscle and renal artery.

Step 3: open the perirenal fat and expose the renal.

Step 4: open the diverticulum and aspirate the stone.

Step 5: methylene blue injection to clarify the diagnosis of calyceal diverticulum.

Step 6: block the renal artery.

Step 7: mucosectomy of renal calyceal diverticulum.

Step 8: methylene blue injection again to confirm diverticulum opening and collecting system.

Step 9: suture the diverticulum opening and methylene blue injection again to confirm diverticulum opening has been closed.

Step 10: suture the kidney and relieve the renal artery occlusion.

Video 1 illustrated each step in detail with narratives to show the tips and tricks.

Discussion

The etiology of calyceal diverticula remains a topic of debate, with a predominant inclination among researchers towards congenital rather than acquired origins, although a unanimous consensus has yet to be reached (8,9). Calyceal diverticulum may be difficult to identify, as most cases could be asymptomatic or lack typical symptoms. Even though it can be established by CTU or intravenous pyelogram (IVP), sometimes the narrow neck of the diverticulum may make it difficult for contrast agents to enter the diverticular cavity, which further complicates the diagnosis. In cases where renal cystic lesions manifest high-density shadows, it becomes imperative to discern between renal calyceal diverticulum and calcifications within renal cysts. In the present case, a CT scan revealed a cystic lesion in the kidney with high-density shadows. Using a prone position CT, we observed that the high-density shadows within the cystic cavity were mobile with changes in body position (Figure 1). Although contrast agents did not enter the cystic cavity, the diagnosis of renal calyceal diverticulum with concomitant stones was made, demonstrating that positional CT examination is a useful method for diagnosing diverticular stones.

Not all patients with calyceal diverticula or calyceal diverticular calculi require surgical treatment. Surgery is considered only when there are evident symptoms such as significant lower back pain, urinary tract infections, gross hematuria, pyuria, and so on (10). The treatment of renal calyceal diverticulum, with or without stones, has evolved from traditional open surgery to minimally invasive procedures. Minimally invasive treatments include ESWL, ureteroscopy, percutaneous nephroscopy, and laparoscopic surgery, each with its own advantages and disadvantages.

ESWL for the treatment of stones in renal calyceal diverticulum is an attractive but controversial option. Despite its minimal invasiveness, ESWL has a relatively low success rate, ranging from 4% to 20% (11), and may have a certain recurrence rate due to its inability to address existing anatomical abnormalities. As a result, ESWL is less commonly used.

With the continuous development of endoscopic techniques, ureteroscopy and percutaneous nephroscopy have become essential in the treatment of renal calyceal diverticulum. The commencement of ureteroscopy involves standard cystoscopy and flexible ureteroscopy. Ureteroscopic intervention for diverticular stones surpasses the efficacy of solitary ESWL and circumvents the elevated complication rates and discomfort associated with more invasive approaches like percutaneous or laparoscopic techniques. This strategy is particularly well-suited for patients harboring small diverticular stones situated in the upper or interpolar regions of the kidney. Notably, lower pole stones, often positioned at acute angles, pose challenges for retrograde management, with a reported success rate dropping from 84% for upper pole diverticula to 29% for lower pole diverticula (12). Percutaneous nephroscopy, performed through a percutaneous tract, allows for stone fragmentation and management of the diverticular wall and neck. The walls of the cavity are then subjected to fulguration using low-current electrocautery. Conclusively, the ostium undergoes dilation, and a nephrostomy tube is strategically positioned across the neck into the primary collecting system. Studies suggest that percutaneous nephroscopy has a higher success rate despite its greater trauma and bleeding risk compared with ureteroscopy. In the percutaneous nephroscopy group, 86% of patients achieved symptom resolution compared to a notably lower proportion of 35% in the ureteroscopy group. Additionally, stone-free rates demonstrated a considerable advantage for percutaneous nephroscopy at 78%, contrasting with the lower rate of 19% observed in the ureteroscopy cohort (13), which making it a preferred surgical approach for renal calyceal diverticulum (14).

While considered the most “invasive” among minimally invasive approaches, laparoscopic surgery for calyceal diverticula demonstrates encouraging perioperative outcomes. It offers the highest stone free rate and closure rate for diverticula. Furthermore, its long-term results seem to exhibit durability (15,16). Laparoscopic surgery does not require the location or size of the diverticulum, and is particularly suitable for patients where percutaneous nephroscopy is challenging or when the diverticular neck is not identifiable with ureteroscopy (6).

Laparoscopic approaches include both transperitoneal and retroperitoneal routes. The transperitoneal route is preferred by surgeons for excision and closure of diverticula located on the lateral aspect of the kidney. However, this approach requires entry into the abdominal cavity, posing risks of intestinal injury and postoperative complications. The retroperitoneal laparoscopic route eliminates concerns about intestinal interference but may be limited in the space available for diverticular excision and closure (17). In 1993, the inaugural instances of laparoscopic treatment for calyceal diverticula were documented. In these initial cases, Gluckman and collaborators employed a five-port approach, identifying the cavity with the aid of methylene blue injected retrograde through an externalized ureteral catheter. The procedural steps included unroofing the cavity, extracting stones, and ablating the lining using argon (18). Since then, various techniques were employed for treating renal calyceal diverticulum by laparoscopic approach, including mucosal electrocautery, gelatin resorcinol formaldehyde glue obliteration and partial nephrectomy (16,17,19). Regardless of the different surgical procedures, the goal is to disrupt or remove the diverticular mucosa to promote diverticular closure. Additionally, closure of the diverticular orifice, involving methods such as coagulation and suturing, aims to block urine reflux and address anatomical abnormalities comprehensively.

In our center, we have also attempted to treat renal calyceal diverticular calculi with percutaneous nephrolithotomy in some cases, but found high recurrent rates of obstruction of the diverticulum orifice. Therefore, we preferred to use partial nephrectomy for treatment. Moreover, as preoperative CTU cannot locate the diverticulum opening for this patient, although the location of the diverticulum is suitable for percutaneous nephrolithotomy, we prefer laparoscopic renal diverticulectomy. We consider that partial nephrectomy may be more precise than mucosal cauterization in destroying the diverticular mucosa. However, there is no consensus regarding the treatment of calyceal diverticula and larger series are imperative, necessitating a collaborative, multi-institutional effort given the relative rarity of the disease.

In our case, we performed laparoscopic excision of the diverticular mucosa followed by suturing of the diverticular orifice through the retroperitoneal approach. Compared to other partial nephrectomy procedure, we think our surgical procedure has several characteristics: (I) before blocking the renal artery, we first unroofed the diverticulum to gain more time during mucosal dissection, minimizing warm ischemia time; (II) mucosal dissection preserved more renal units compared to partial nephrectomy.

While the presented surgical video is a demonstration of a specific case, our aim is to disclose the specific operational procedures and details of this surgical method. We hope this video will provide clinical urologists with a reference for the treatment of renal calyceal diverticulum and serve as guidance for those who, despite preoperative misdiagnosis as a renal cyst and undergoing cystic unroofing, are confirmed intraoperatively to have renal calyceal diverticulum, allowing for diverticular excision according to the presented surgical method.

Acknowledgments

Funding: This study was supported by grant from Undergraduate Teaching Quality and Teaching Reform Cultivation Project of the First Affiliated Hospital of Sun Yat-sen University (Grant No. P12220011-230118).

Footnote

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://aos.amegroups.com/article/view/10.21037/aos-24-2/rc

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://aos.amegroups.com/article/view/10.21037/aos-24-2/coif). The 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). Written informed consent was obtained from the patient publication of this manuscript, and any accompanying images and video. A copy of the written consent is available for review by the editorial office of this journal.

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/.

References

1. Smyth N, Somani B, Rai B, et al. Treatment Options for Calyceal Diverticula. Curr Urol Rep 2019;20:37. [Crossref] [PubMed]
2. Matlaga BR, Miller NL, Terry C, et al. The pathogenesis of calyceal diverticular calculi. Urol Res 2007;35:35-40. [Crossref] [PubMed]
3. Timmons JW Jr, Malek RS, Hattery RR, et al. Caliceal diverticulum. J Urol 1975;114:6-9. [Crossref] [PubMed]
4. Middleton AW Jr, Pfister RC. Stone-containing pyelocaliceal diverticulum: embryogenic, anatomic, radiologic and clinical characteristics. J Urol 1974;111:2-6. [Crossref] [PubMed]
5. Waingankar N, Hayek S, Smith AD, et al. Calyceal diverticula: a comprehensive review. Rev Urol 2014;16:29-43. [PubMed]
6. Gonzalez RD, Whiting B, Canales BK. Laparoscopic calyceal diverticulectomy: video review of techniques and outcomes. J Endourol 2011;25:1591-5. [Crossref] [PubMed]
7. Zhang K, Ma Y, Wu J, et al. The SUPER reporting guideline suggested for reporting of surgical technique. Hepatobiliary Surg Nutr 2023;12:534-44. [Crossref] [PubMed]
8. Abeshouse BS, Abeshouse GA. Calyceal diverticulum: a report of sixteen cases and review of the literature. Urol Int 1963;15:329-57. [Crossref] [PubMed]
9. MATHIESON AJ. Calyceal diverticulum: a case with a discussion and review of the condition. Br J Urol 1953;25:147-54. [Crossref] [PubMed]
10. Gross AJ, Herrmann TR. Management of stones in calyceal diverticulum. Curr Opin Urol 2007;17:136-40. [Crossref] [PubMed]
11. Chen YW, Shen SH, Chang YH, et al. Squamous Cell Carcinoma Arising From a Renal Calyceal Diverticulum. Urology 2016;95:e5-6. [Crossref] [PubMed]
12. Batter SJ, Dretler SP. Ureterorenoscopic approach to the symptomatic caliceal diverticulum. J Urol 1997;158:709-13. [Crossref] [PubMed]
13. Auge BK, Munver R, Kourambas J, et al. Endoscopic management of symptomatic caliceal diverticula: a retrospective comparison of percutaneous nephrolithotripsy and ureteroscopy. J Endourol 2002;16:557-63. [Crossref] [PubMed]
14. Dean NS, Guo JN, Krambeck AE. Percutaneous management of caliceal diverticula: a narrative review. Curr Opin Urol 2023;33:333-8. [Crossref] [PubMed]
15. Miller SD, Ng CS, Streem SB, et al. Laparoscopic management of caliceal diverticular calculi. J Urol 2002;167:1248-52. [Crossref] [PubMed]
16. Terai A, Habuchi T, Terachi T, et al. Retroperitoneoscopic treatment of caliceal diverticular calculi: report of two cases and review of the literature. J Endourol 2004;18:672-4. [Crossref] [PubMed]
17. Wyler SF, Bachmann A, Jayet C, et al. Retroperitoneoscopic management of caliceal diverticular calculi. Urology 2005;65:380-3. [Crossref] [PubMed]
18. Gluckman GR, Stoller M, Irby P. Laparoscopic pyelocaliceal diverticula ablation. J Endourol 1993;7:315-7. [Crossref] [PubMed]
19. Hoznek A, Herard A, Ogiez N, et al. Symptomatic caliceal diverticula treated with extraperitoneal laparoscopic marsupialization fulguration and gelatin resorcinol formaldehyde glue obliteration. J Urol 1998;160:352-5. [Crossref] [PubMed]