PERCUTANEOUS ABLATION OF CALICEAL DIVERTICULUM: LONG-TERM FOLLOWUP

0022-5347/00/1631-0028/0 THE JOURNAL OF UROLOGY® Copyright © 2000 by AMERICAN UROLOGICAL ASSOCIATION, INC.®

Vol. 163, 28 –32, January 2000 Printed in U.S.A.

PERCUTANEOUS ABLATION OF CALICEAL DIVERTICULUM: LONGTERM FOLLOWUP MANOJ MONGA,* ROBERT SMITH, HECTOR FERRAL

AND

RAJU THOMAS

From the Departments of Urology and Radiology, Tulane University and Department of Radiology, Louisiana State University, New Orleans, Louisiana

ABSTRACT

Purpose: A caliceal diverticulum is a nonsecretory cavity that serves as a conduit for urinary stasis and its ensuing complications. Indications for intervention and modes of therapy are controversial. We report a series of patients treated with a percutaneous endourological approach to ablation of the diverticular cavity. Materials and Methods: A total of 14 patients underwent percutaneous ablation of a caliceal diverticulum for flank pain a mean of 15.5 months in duration. These caliceal diverticula were associated with urinary tract infection in 43% of cases and/or renal calculi in 78%. Mean calculus diameter was 10.2 mm. and mean diverticular diameter was 10.9 mm. An open ended ureteral catheter was placed into the renal pelvis via cystoscopy. Retrograde instillation of radiopaque contrast medium facilitated the localization of a percutaneous renal puncture made directly into the caliceal diverticulum. A flexible tip guide wire was coiled in the diverticulum, and no effort was made to traverse the infundibulum and establish continuity with the remainder of the collecting system. Tract dilation into the caliceal diverticulum was performed, and percutaneous stone fragmentation and extraction were accomplished. The lining of the caliceal diverticulum was electrocauterized using a roller ball electrode. A balloon nephrostomy tube consisting of a Foley catheter with the tip cut off was positioned into the diverticulum. An indwelling ureteral stent was placed and a Foley catheter provided bladder drainage for 48 hours to maintain a low pressure system. The nephrostomy tube was removed after 24 to 48 hours and the ureteral stent was removed after 2 to 4 weeks. Results: Mean operative time was 162 minutes and mean hospital stay was 2.3 days. Obliteration of the diverticular infundibulum and cavity was documented by contrast radiography (excretory urography or retrograde pyelography), and noncontrast and contrast enhanced computerized tomography, respectively, in all 14 patients. No patients have had recurrent symptoms, calculi or urinary tract infection at a mean 38-month followup. Conclusions: Percutaneous electrocautery ablation of caliceal diverticula without cannulation or dilation of the diverticular infundibulum represents a safe and effective mode of therapy. Careful patient selection and preparation optimize the efficacy of this technique. KEY WORDS: kidney, diverticulum, calculi, catheter ablation

Caliceal diverticula are smooth walled, nonsecretory cavities within the renal parenchyma that are lined with transitional cell epithelium and receive urine by passive retrograde filling from the adjacent collecting system, usually through a narrow infundibulum (fig. 1). Caliceal diverticula are believed to be congenital in origin.1 They are an incidental finding in 0.21% to 0.45% of excretory urography (IVP) studies and the majority are less than 1 cm. in diameter.1–3 There is no predilection for gender or kidney side and they are bilateral in 3% of cases.1 Uncomplicated asymptomatic caliceal diverticula may be managed conservatively without routine followup imaging. Urine stasis may predispose to infection and calculous formation. Indications for therapy include pain, infection, calculous formation, hematuria or large size that compresses a contiguous calix or parenchyma.1, 4 Calculi are concomitant in 9.5% to 39% of cases and rarely pass spontaneously due to the narrow diverticular infundibulum.1 Recurrent infections may be attributable to the diverticulum in 25% of cases.5 Obstruction of the diverticular neck may lead to sepsis,

abscess formation or hypertension.3 A fatal case of spontaneous hemorrhage and rupture of a caliceal diverticulum has been reported.4 When tuberculosis is prevalent, the differential diagnosis of cortical cavitation secondary to renal tuberculosis should be considered since the radiological appearances may be similar.6 Traditional therapy for caliceal diverticula includes open surgical nephrostomy with closure of the infundibulum, and marsupialization and fulguration of the diverticular cavity or partial or total nephrectomy.1, 3 Some routinely perform open marsupialization with obliteration of the cavity with perinephric fat.6 During the last decade the use of extracorporeal shock wave lithotripsy (ESWL†) and percutaneous techniques have been described. We report our experience with the percutaneous management of caliceal diverticula at a tertiary referral center. MATERIALS AND METHODS

Percutaneous caliceal diverticular ablation was performed in 8 women and 6 men 16 to 46 years old (mean age 33.4). Table 1 shows the locations of these diverticula. Five patients (30%) in whom ESWL had been unsuccessful had a history of

Accepted for publication August 13, 1999. * Current address: Department of Urology–Hillcrest, University of California, San Diego, 200 West Arbor Dr., San Diego, California 92103-8897.

† Dornier Medical Systems, Inc., Marietta, Georgia. 28

PERCUTANEOUS ABLATION OF CALICEAL DIVERTICULUM

FIG. 1. IVP shows caliceal diverticulum in upper pole of right kidney.

various degrees of symptoms ranging from mild to severe flank pain for a mean of 15.5 months (range 1 to 36). Most of these patients were referred for diverticular management. There were 6 patients (43%) with a history of recurrent urinary tract infection and in 1 a perinephric abscess resolved with percutaneous drainage. Of the 14 patients 11 (78%) had associated calculi, including a solitary calculus within the diverticulum in 7 and multiple small calculi in 4. Calculous size ranged from 4 to 30 mm. (mean 10.2). Mean diverticular diameter was 10.9 mm. (range 4 to 48). Patients were counseled on the options available, including observation, percutaneous ablation and removal of calculi if present, and open surgical excision of the diverticulum. They were informed of the risks of percutaneous renal surgery, including bleeding, blood transfusion and pneumothorax. After induction of general endotracheal anesthesia patients underwent placement of an open ended ureteral catheter into the renal pelvis via cystoscopy. This catheter was used intraoperatively to opacify the caliceal system with radiopaque contrast medium to aid in localizing the percutaneous puncture. A Foley catheter was left indwelling to drain the bladder throughout the procedure. Intravenous broadspectrum antibiotics were administered preoperatively. The patient was then repositioned prone with liberal egg crate cushioning at all potential pressure points. The flank and back on the side of interest were prepared and draped in a sterile fashion. A percutaneous puncture was made into the caliceal diverticulum using a needle under fluoroscopic guidance with visualization of the diverticulum aided by injecting radiopaque contrast medium through the ureteral catheter. Calculi within the diverticulum were also used as a location guide. After access was obtained a flexible tip guide wire was coiled in the diverticulum (fig. 2). When possible, a guide wire was advanced through the infundibulum of the diverticulum into the calix, pelvis, ureter and bladder, and used as a safety wire. No unusual effort was made to identify the infundibu-

29

lum during the access phase. In 71% of the cases the guide wire was coiled within the diverticulum. The nephrostomy tract was sequentially dilated using the Amplatz sequential dilator system to 28 or 30Fr, or a percutaneous balloon dilation system. Tract dilation in these patients was especially challenging, since most guide wires were coiled within the diverticulum and not down the ureter. Calculi or pooled injected retrograde contrast medium aided in this dilation process. Care was taken to dilate only up to but not through the infundibulum of the diverticulum. The 28 or 30Fr Amplatz sheath was positioned with its tip in the diverticular cavity and a rigid nephroscope was introduced through it. When present, calculi were extracted with grasping forceps, or fragmented with an ultrasonic, electrohydraulic or holmium laser lithotriptor. The ultrasonic lithotriptor was routinely used to suction fragments within the diverticulum. Stone fragments were sent for analysis. A transurethral resection resectoscope with a 26Fr resecting sheath was then introduced through the Amplatz sheath. The whole diverticular cavity lining was fulgurated with a low electrocautery unit setting at 15 to 20 w. (fig. 3, A). A 16 or 18Fr Foley catheter with the tip amputated to prevent traversing of the infundibulum was placed in the diverticular cavity and balloon inflated with 1 to 3 cc contrast medium depending on diverticular size, so that it snugly fit within the fulgurated cavity (fig. 3, B). Gentle nephrostography confirmed placement in the diverticular cavity instead of in the caliceal system. Before termination of the procedure the open ended ureteral catheter was converted to an indwelling Double-J* stent. A Foley catheter was used to drain the bladder for approximately 48 hours to maintain a low pressure urinary drainage system. All patients received a postoperative course of antibiotics for 1 week. Percutaneous diverticular tubes were removed in 24 to 48 hours. Ureteral stents were removed 2 to 4 weeks after the procedure in asymptomatic patients at the discretion of the surgeon or referring urologist. Patients were evaluated for residual flank pain, infection and residual stone fragments. Obliteration of the diverticular infundibulum was documented by contrast radiography (IVP or retrograde pyelography), and by noncontrast and contrast enhanced computerized tomography (CT) (fig. 4). * Medical Engineering Corp., New York, New York.

TABLE 1. Location of caliceal diverticula Calix

No. Anterior

No. Posterior

Total

Upper Mid Lower Totals

3 0 1 4

7 2 1 10

10 2 2 14

FIG. 2. Guide wire is coiled in diverticulum and open ended ureteral catheter is visible within right renal pelvis.

30

PERCUTANEOUS ABLATION OF CALICEAL DIVERTICULUM

FIG. 3. A, Amplatz sheath is in place. After calculi removal diverticulum lining is fulgurated with electrocautery loop. B, contrast material is present in Foley catheter within fulgurated diverticular cavity.

RESULTS

Mean operative time was 162 minutes (range 96 to 246) and average hospital stay was 2.3 days (range 0 to 4). All patients underwent a 1-step, same day percutaneous access and fulguration procedure. Pneumothorax was managed by tube thoracostomy for 24 hours in a patient who had previously undergone percutaneous drainage of an abscess in the upper pole caliceal diverticulum. All patients were followed a mean of 38 months (range 8 to 74) and all were rendered stone-free. They reported by history symptomatic improvement of pain and those who were asymptomatic preoperatively did not report any pain postoperatively. To evaluate further the efficacy of diverticular ablation CT was performed in these patients a mean of 14 months postoperatively (range 6 to 22) and revealed no obvious recurrence. There was no evidence of any residual stone fragments. A minimal scar was noted at the site of the treated diverticulum. In 3 patients scar tissue associated with the percutaneous nephrostomy tract was also visualized. There was no contrast medium pooling, suggestive of residual or recurrent diverticula, in any patient. Stone analysis revealed a calcium oxalate and struvite composition in 71% and 29% of the cases, respectively. Of the 6 patients with a urinary tract infection preoperatively 2 have had episodes of cystitis postoperatively. However, no incidence of pyelonephritis was recorded. DISCUSSION

Therapeutic options for symptomatic caliceal diverticulum include ESWL, percutaneous management and open surgery. Most agree that ESWL is of limited value in the management of caliceal diverticular calculi with stone-free rates of 0% to 58% (table 2).1, 7, 9, 10, 16 At centers where ESWL is performed to manage diverticula with calculi less than 1.5 cm. and radiologically patent diverticular necks, stone-free rates up

TABLE 2. Results of ESWL for caliceal diverticular disease References

No. Pts.

% Stone-Free

% Symptom-Free

Psihramis and Dretler1 Wilbert et al9 Streem et al7 Frattini et al10 Jones et al16

10 16 19 13 26

20 20 58 0 4

70 53 37 36

to 58% are reported.7, 8 In addition, many patients are rendered symptom-free after ESWL although they may retain significant stone fragments (table 2).1, 7, 9 Percutaneous management of caliceal diverticula is challenging because the cavities are often small, making localization for direct access difficult.1 Caliceal diverticula may be located in the upper (70%), lower (18%) or mid (12%) calix.4 Because the majority of diverticula are located in the upper third of the caliceal system, the risk of pneumothorax is increased.1 Some recommend percutaneous management as the primary modality for small caliceal diverticula, while open surgery is reserved for large diverticula with renal parenchymal damage.2, 10 Direct puncture of the caliceal diverticulum enables the use of the rigid nephroscope and electrocautery ablation makes it unnecessary to locate the diverticular neck.2 Advantages of the rigid nephroscope include better optics, and larger irrigation and working channels, permitting the use of the ultrasonic lithotriptor.2 Ideally a safety wire is placed through the diverticular neck into the renal pelvis but it may be coiled in the diverticular cavity if the neck cannot be cannulated.2, 3 Alternatively if wires cannot be coiled in the cavity or advanced through its neck, they may be punctured through the far wall of the cavity and anchored in the adjacent renal parenchyma.11 Care should be taken to limit fulguration to the nonsecretory lining of the diverticulum to

FIG. 4. CT reveals obliterated diverticular cavity. A, preoperatively. B, postoperatively

31

PERCUTANEOUS ABLATION OF CALICEAL DIVERTICULUM

avoid inadvertently fulgurating draining collecting ducts, which would lead to obstruction and focal parenchymal loss.2 Table 3 lists the results of percutaneous management of caliceal diverticula.2, 3, 5, 16 Ellis et al reported a series of patients with caliceal diverticula who were symptomatic with infection or calculus.2 These patients were treated with an assortment of techniques, including direct puncture and dilation of the diverticular neck with or without Bugby electrode fulguration, indirect puncture with dilation of the diverticular neck and tetracycline sclerosis. Nephrostomy tubes were left in the renal pelvis traversing the diverticular cavity and infundibulum in the majority of cases. Bugby fulguration was performed during a repeat procedure 2 to 4 days after initial puncture. Tetracycline sclerosis is discouraged because of the risks of overdose, and extravasation and entry into the collecting system, causing widespread sclerosis. Hulbert et al reported excellent results with direct diverticular puncture, stone removal and nephrostomy tube drainage for 2 weeks without fulguration.3 They concluded that the trauma of dilation stimulated granulation tissue formation, which obliterated the diverticular cavity. Indirect puncture was not successful for obliterating the diverticular cavity. Fulguration was recommended for large volume diverticula in which percutaneous dilation would traumatize only part of the cavity lining and obliteration may be prevented by an increased area of supporting renal parenchyma.12 Bellman et al used a percutaneous technique for ablating the diverticular cavity, as in our series, except they dilated the diverticular neck and maintained a nephrostomy tube across the diverticular neck for 48 hours.5 Hulbert et al advocated percutaneous infundibuloplasty with balloon dilation to maintain a larger communication between the diverticular cavity and collecting system, as opposed to obliteration of the cavity.3 Externalized stents were retained for 4 to 8 weeks. In that series 67% of the diverticular necks remained patent, while 22% of the cavities and necks were obliterated, and 11% of the diverticula recurred. The proposed advantage of this technique over fulguration of the diverticulum was the avoidance of inadvertent fulguration of functioning collecting ducts that drain into a hydrocalix. Frattini et al recommended injecting human fibrin glue through the percutaneous nephrostomy into the diverticular cavity after electrical fulguration of the diverticular lining.10 Ruckle and Segura described transperitoneal laparoscopic marsupialization and fulguration of an anterior diverticulum adjacent to the renal hilum in which location precluded percutaneous management.14 Pang et al reported that 75% of patients were rendered stone-free with combined ESWL and a retrograde endoscopic approach to caliceal diverticular calculi, although 23% required a repeat retrograde or percutaneous procedure.15 The main limitations of this technique are identification of the diverticular neck and management of lower pole diverticula.16 Another concern is that long-term followup may reveal significant ureteropelvic junction stricture rates with this technique.5 Although several methods have been described with various degrees of success, there is no consensus on whether the goal of management should be obliteration of the diverticular cavity. Minor complications during percutaneous ablation and cal-

culous removal include hemorrhage, pneumothorax, persistent urinary extravasation and mild extravasation of irrigant.2, 5 Major complications include renal pelvis perforation with urinoma formation, pneumothorax or hemothorax requiring tube thoracostomy and massive hemorrhage requiring balloon tamponade.2, 5, 13 In our series the major complication was pneumothorax in 1 case that was recognized before termination of the procedure. The patient recovered with no long-term sequelae. Ellis et al reported that most calculi from caliceal diverticuli were a mixture of calcium oxalate monohydrate and hydroxyapatite.2 Hulbert et al described stone analyses of calcium oxalate in 55% of cases and struvite in 45%.3 Lang stated that the majority of diverticular calculi were struvite.13 We noted a composition distribution of calcium oxalate in 75% of cases and struvite in 25%. In previous series of percutaneous management of caliceal diverticula mean hospital stay was 2.8 to 4.6 days.3, 13 In our series mean hospital stay was 2.3 days (range 0 to 4). Bellman et al reported a 14% transfusion rate.5 However, blood loss in our series was clinically not significant enough to warrant transfusion. The smallest previously reported caliceal diverticulum that was managed successfully by a percutaneous approach was 8 3 10 mm.2 However, we successfully accessed and ablated symptomatic diverticula measuring 4 mm. in the largest diameter in 2 patients. We believe that percutaneous ablation of a caliceal diverticulum by electrode fulguration without dilation of the diverticular neck and placement of a nephrostomy tube may be superior to other techniques in regard to success in obliterating the diverticular cavity. Intuitively it seems reasonable not to dilate a cavity and stent it with a nephrostomy tube if the goal is to collapse the cavity. We believe that this is especially important for mid and lower pole caliceal diverticula that may have dependent pooling in the cavity. Placement of a drainage tube in the diverticular cavity instead of through the diverticular neck maintains a re-entry tract in the event that it is needed without maintaining patency of the communication with the collecting system. The method that we describe is undoubtedly challenging, since the guide wire is often only curled within the diverticular cavity without the security of having it traverse the ureter down to the bladder. We believe that most caliceal diverticula may be managed by this technique. However, one must be cautious when approaching smaller cavities. We used extreme caution during tract dilation and, thus, did not observe inadvertent tube removal or tract loss. No other unusual complications developed. It is possible that complete obliteration of a diverticulum 20 cc or greater may be challenging. CT may be the best radiographic measure of success of caliceal ablation, since IVP does not permit visualization of all diverticula.2 Obliteration of the diverticular neck to prevent the passive flow of contrast medium into the diverticular cavity does not translate to obliteration of the cavity. CONCLUSIONS

Percutaneous ablation of caliceal diverticula may be the ideal method of managing these space occupying cavities within the kidney. Long-term success may be defined by the

TABLE 3. Results of percutaneous nephrostolithotomy with caliceal ablation References

No. Pts.

% Stone-Free

% Symptom-Free

% Calculi Obliterated (followup)

% Major Complication

Ellis et al2 Hulbert et al3 Jones et al16 Bellman et al5

12 10 14 20

88 70 100 95

88 Unknown 88 100

75 (IVP) 66 (unspecified) — 80 (IVP)

8 0 — 7

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PERCUTANEOUS ABLATION OF CALICEAL DIVERTICULUM

nonrecurrence of diverticular calculi, urinary tract infection and flank pain. We present objective evidence of obliteration of the diverticular cavity by electrocautery ablation with confirmatory postoperative CT. Randomized trials of the various percutaneous techniques discussed with long-term CT followup are ideally needed to compare efficacy and safety. REFERENCES

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calculi with extracorporeal shock-wave lithotripsy: patient selection and extended followup. J Urol, part 2, 148: 1043, 1992. Wilbert, D. M., Jenny, E., Stoecke, M. et al: Caliceal diverticular stones: is ESWL worthwhile? J Urol, 135: 183A, abstract 316, 1986. Frattini, A., Ferretti, S., Salsi, P. et al: Caliceal diverticula: notes on endourological technique. Acta Bio-Med Ateneo Parmense, 65: 17, 1994. Glanz, S., Laungani, G. B., Gordon, D. H. et al: Percutaneous removal of renal caliceal calculi: an alternative approach. Urol Radiol, 8: 40, 1986. Hulbert, J. C., Lapointe, S., Reddy, P. K. et al: Percutaneous endoscopic fulguration of a large volume caliceal diverticulum. J Urol, 138: 116, 1987. Lang, E. K.: Percutaneous infundibuloplasty: management of caliceal diverticula and infundibular stenosis. Radiology, 181: 871, 1991. Ruckle, H. C. and Segura, J. W.: Laparoscopic treatment of a stone-filled caliceal diverticulum: a definitive, minimally invasive therapeutic option. J Urol, 151: 122, 1994. Pang, K., David, R. and Fuchs, G. J.: Treatment of stones in caliceal diverticula using retrograde endoscopic approach: critical assessment after 2 years. J Endourol, Suppl, 6: F15, 1992. Jones, J. A., Lingeman, J. E. and Steidle, C. P.: The roles of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy in the management of pyelocaliceal diverticula. J Urol, 146: 724, 1991.