Percutaneous Management of Calyceal Diverticulum
NYU Case of the Month, September 2020
Philip T. Zhao, MD
Urology Stone Program, NYU Langone Tisch Hospital, Department of Urology, NYU Grossman School of Medicine, New York, NY
[Rev Urol. 2020;22(3):135–137]
© 2020 MedReviews®, LLC
A 31-year-old woman presented to NYU Langone with intermittent right flank pain of 6 months’ duration. The pain was sharp, non-radiating, and worsened with fluid intake. The patient had originally been in Italy, where she was diagnosed with kidney stones and underwent 3 ureteroscopic treatments, but her pain persisted. She was unable to provide prior medical records delineating what operations and perioperative care she had been provided in Italy. A recent CT urogram showed a 4-cm right posterior upper pole calyceal diverticulum (CD) with a 9-mm stone (Figure 1). There was no hydronephrosis and the left kidney appeared normal. She had had one prior episode of urinary tract infection (UTI) and had been treated to effect. In the office on presentation, she complained of persistent and intermittent right flank pain but did not display costovertebral angle (CVA) tenderness on examination. Her renal function was normal, with Cr 0.8 mg/dL and office urinalysis dipstick negative for UTI.
The patient was counseled on treatment options. Given the prior failed attempts with ureteroscopic evaluation, it was recommended that she undergo an antegrade approach with right percutaneous renal access.
Cystoscopy and ureteral catheterization, with retrograde pyelogram identified the upper pole diverticulum under fluoroscopy (Figure 2). Right percutaneous access was made directly into the posterior upper pole CD using the bull’s eye technique (Figure 3). A 24F access sheath was placed supra-12th rib, which allowed inspection of the diverticulum with nephroscopy (Figure 4).
The 9-mm stone and additional punctate stones were removed intact and an attempt was made to identify the upper pole infundibulum leading to the rest of the collecting system. The infundibular entrance was not identified using both rigid and flexible nephroscopes. The mucosa of the diverticulum was fulgurated with a monopolar rollerball and FLOSEAL Hemostatic Matrix (Baxter, Deerfield, IL) was injected to help collapse the diverticulum. No drainage tube (nephrostomy or stent) was placed and the patient was discharged home on the first postoperative day with minimal discomfort.
One month later, office US showed resolution of the CD with no residual stones or hydrocalyx (Figure 5).
Although CD incidence is less than 1% in adults, CDs represent a unique treatment challenge for urologists. CDs can mimic other urologic conditions such as renal cysts and even tumors. In approximately 50% of cases, the CD harbors stones.1 The standard diagnostic modality is a CT urogram, which allows better definition than US or IV pyelogram, of the infundibulum and originating calyx as well as of the CD itself. Although most CDs are asymptomatic, pain, recurrent UTIs, persistent gross hematuria, and loss of renal function are indications for surgical intervention. The choice of treatment depends on the anatomic location and anatomy of the CD as well as on the stone burden. Performance of current surgical techniques has been enhanced by existing technologies. Current treatments include shockwave lithotripsy (SWL), flexible ureterorenoscopy (URS), percutaneous nephrolithotomy (PCNL), and laparoscopic/robotic diverticulectomy.
SWL has a low stone-free rate of 4% to 20% but a high symptom-free rate of almost 65%.2 Its use is restricted mostly to diverticula with wide mouths and short infundibula. The limiting factor for SWL is the poor drainage of CDs. SWL is generally reserved for symptomatic patients with stone burden inside the CD who are not optimal surgical candidates.
Flexible URS has a stone-free rate of 73% to 95% for a stone burden of less than 2 cm and is less invasive than PCNL.3 For CDs located in the superior anterior location, URS is often the first line of treatment. The ostium can sometimes be a small dimple. If visualization is difficult, the Blue Spritz technique can be used, whereby methylene blue is instilled into the collecting system and then removed. As saline irrigation is reintroduced into the system, blue dye in the diverticulum escapes, allowing for identification of the ostium. The narrow infundibulum is lasered or balloon dilated to allow introduction of the ureteroscope into the diverticulum. Unfortunately, in URS the ostium cannot be identified in up to one-third of patients.
PCNL is by far the mainstay of CD treatment in terms of access into larger, more complex, and posterior diverticula. PCNL consistently has better success rates than URS and SWL and some series have achieved a 96% stonefree rate.4 The key is to coil the wire in the diverticulum and dilate the access tract without losing the wire. Once the stone burden is removed from the diverticulum, the ostium must be found and dilated to reconnect the calyx with the rest of the collecting system. If the ostium cannot be identified and incised/dilated, the cavity wall should be fulgurated with low-energy electrocautery. It is postulated that the secretory lining of the CD is obliterated, so urine is no longer expelled into the CD. In our case, we used a rollerball and completely ablated the diverticular surface. Monga and colleagues achieved 100% stone-free and symptom-free results with this method at 38 months.5
Laparoscopic and robotic approaches to diverticulectomy can access more anterior lower pole CDs that are not amenable to the PCNL approach. The optimal candidate for this approach has a large stone burden and thin overlying parenchyma. This approach allows for direct incision, fulguration, and marsupialization of the CD. Some surgeons advocate injection of coagulant material or surgical mesh into the cavity to allow the diverticulum to collapse and thus decrease the likelihood of recurrent stone formation. Long-term results of laparoscopic/robotic approaches seem durable.
CDs are rare and often asymptomatic. Symptomatic CDs usually involve a stone burden. Treatment is based on diverticular anatomy, location, and stone burden. PCNL remains the mainstay of surgical treatment for posterior CDs given its high stone clearance rate, ability to access the diverticulum regardless of ostium identification, and better capability to directly ablate the cavity. URS is best suited for treatment of upper and anterior pole CDs and smaller stones. Laparoscopic and robotic approaches are reserved for patients who are refractory to other treatment modalities and who have a large stone burden and anteriorly located diverticula.