Yaniv Shilo, MD
Timothy D. Averch, MD, FACS
BASICS
DESCRIPTION
• Calyceal diverticula are nonsecretory, transitional cell epithelium-lined cystic cavities within the renal parenchyma.
• The cavity is usually filled retrograde from urine in the collecting system.
• Mostly unilateral.
• Most prevalent in upper calyces (70%)
• No gender nor laterality predilection
• Bilateral in 3%
• Sometimes called pelvicaliceal diverticula
EPIDEMIOLOGY
Incidence
<1%
Prevalence
Found in up to 0.45% of routine intravenous pyelogram studies.
RISK FACTORS
N/A
Genetics
N/A
PATHOPHYSIOLOGY
• Congenital in origin due to failure of regression of ureteric bud.
• Urine enters diverticulum passively via narrow communication with collecting system.
• Urine trapped in diverticulum predisposes to infection and stone formation.
ASSOCIATED CONDITIONS
• Flank pain
• Calyceal calculi (9–50%)
• Recurrent urinary tract infection (UTI)
• Hematuria
GENERAL PREVENTION
N/A
DIAGNOSIS
HISTORY
• Mostly incidental finding on imaging
• Flank pain
• Microhematuria or macrohematuria
• Recurrent UTI
PHYSICAL EXAM
• Usually not suggestive
• Possible flank pain
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Urinalysis
– Microhematuria and pyuria
• Urine culture
– Bacterial persistence
Imaging
• Abdominal x-ray (KUB):
– May demonstrate characteristic radiopaque “milk of calcium,” which appears as a half moon or meniscus-shaped calcification
Milk of calcium should change its location when changing positioning from erect to lateral decubitus.
– Case reports of confusion as being diagnosed as rib metastasis
• Ultrasound (US):
– Provide diagnosis in up to 80% of the cases.
– Shows cystic lesion with curvilinear, plaque-like calcification along its posterior wall.
– Exam while changing positioning is needed to differ from complex cyst.
• Intravenous pyelography (IVP):
– Delayed imaging demonstrates the diverticulum, as it fills retrogradely from its connection to the renal pelvis or calyx.
• CT urography (CTU):
– Delayed imaging is critical to demonstrate contrast medium within an apparent cystic mass
Diagnostic Procedures/Surgery
• Retrograde pyelogram:
– Allows greater distension of the collecting system than can be attained with IVP.
– Delineating anatomy and assist in planning the appropriate treatment approach.
Pathologic Findings
• Lined by nonsecretory transitional epithelium.
• Retrograde reflux of urine from the calyx via the diverticular neck can cause stasis with stones in calyceal diverticula in up to 50% of cases
DIFFERENTIAL DIAGNOSIS
• Calcified tumor
• Complicated renal cyst
• Kidney abscess
• Nephrolithiasis
TREATMENT
GENERAL MEASURES
• In case of uncomplicated, asymptomatic calyceal diverticulum treatment can be conservative with no further imaging follow-up.
• Indications for therapy include pain, recurrent infection, increased calculus growth, hematuria or large size that compresses or progressively damages contiguous renal parenchyma
MEDICATION
First Line
Antibiotic treatment can be used for recurrent UTIs; otherwise no specific role
Second Line
N/A
SURGERY/OTHER PROCEDURES
• Shock wave lithotripsy (SWL):
– May be suitable for calyceal diverticulum with small calculi and wide infundibulum (1)[B].
– Can resolve flank pain.
– Limitations are due to inadequate passage of stone fragments through the infundibulum and lack of anomaly repair.
• Ureteroscopy (URS):
– Most suitable as initial treatment for calculi <1.5 cm located in the middle or upper pole diverticulum and specifically in the anterior aspect.
– Involves mechanical dilatation of the diverticular neck and removal of calculi if present.
– Ablation of diverticular cavity is not a common practice.
• Percutaneous nephrolithotomy (PCNL):
– Considered to be the definitive surgical treatment specifically for diverticula containing stone burden >1.5 cm in the posterior aspect.
– Challenging when only thin layer of parenchyma surrounding the diverticula or located anteriorly.
– Requires direct access to diverticulum and infundibulum widening.
– Ablation of the calyceal diverticulum cavity is recommended (2)[B].
• Laparoscopic nephrolithotomy (LAP):
– May be advantageous in cases of anterior diverticula, diverticula covered with thin layer, diverticula containing large calculi or large diverticula (3)[B].
– Includes unroofing of the diverticulum and calculi removal if present.
– Ablation of the remaining cavity and neck.
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
N/A
Complementary & Alternative Therapies
N/A
ONGOING CARE
PROGNOSIS
• SWL:
– Stone-free rate is relatively low (up to 60%), however, symptom-free rate is higher (4)[B].
• URS:
– Stone-free and symptom-free rates can be high when infundibulum is identified
– In significant number of diverticula the infundibulum cannot be found (4)[B].
• PCNL:
– Excellent stone-free and symptom-free rates (over 80%).
– Long-term results remain good.
• LAP:
– Initial results show high stone-free rate and diverticular ablation.
COMPLICATIONS
• Calyceal diverticula:
– Secondary infection
– Chronic pain with stones
– Compression of surrounding tissue
• SWL:
– Flank pain
– Infection
– Subcapsular or perinephric hematoma
• URS:
– Bleeding
– Thermal injury to ureteral wall or renal parenchyma
– Ureteral perforation
– Sepsis
• PCNL:
– Bleeding
– Urinary extravasation
– Pneumothorax
– Hemothorax
– Collecting system perforation
FOLLOW-UP
Patient Monitoring
• Radiographic imaging with either CTU, IVP, or kidney US should be done 6–8 wk postoperatively.
• Patients with calculi contained in diverticulum may need metabolic evaluation as these patients tend to have metabolic abnormalities similar to patients with nephrolithiasis (5)[B].
Patient Resources
N/A
REFERENCES
1. Streem SB, Yost A. Treatment of caliceal diverticular calculi with extracorporeal shock wave lithotripsy: Patient selection and extended followup. J Urol. 1992;148:1043–1046.
2. Shalhav AL, Soble JJ, Nakada SY, et al. Long- term outcome of caliceal diverticula following percutaneous endosurgical management. J Urol. 1998;160(5):1635–1639.
3. Gonzalez RD, Whiting B, Canales BK. Laparoscopic calyceal diverticulectomy: Video review of techniques and outcomes. J Endourol. 2011;25(10):1591–1595.
4. Rapp DE, Gerber GS. Management of caliceal diverticula. J Endourol. 2004;18(9):805–810.
5. Auge BK, Maloney ME, Mathias BJ, et al. Metabolic abnormalities associated with calyceal diverticular stones. BJU Int. 2006;97(5):1053–1056.
ADDITIONAL READING
• Canales B, Monga M. Surgical management of the calyceal diverticulum. Curr Opin Urol. 2003;13(3):255–260.
• Matlaga BR, Miller NL, Terry C, et al. The pathogenesis of calyceal diverticular calculi. Urol Res. 2007;35(1):35–40.
See Also (Topic, Algorithm, Media)
• Calcifications, Renal
• Calyceal Diverticula Image 
• Nephrocalcinosis
• Urolithiasis, Adult, General considerations
• Urolithiasis, Renal
CODES
ICD9
• 592.0 Calculus of kidney
• 593.89 Other specified disorders of kidney and ureter
• 753.3 Other specified anomalies of kidney
ICD10
• N20.0 Calculus of kidney
• N28.89 Other specified disorders of kidney and ureter
• Q63.8 Other specified congenital malformations of kidney
CLINICAL/SURGICAL PEARLS
• Usually located on upper calyces.
• Associate disorders include—calyceal calculi, recurrent UTI, and flank pain.
• URS is suitable for anterior midpole or upper diverticula with calculi <1.5 cm.
• PCNL is the treatment of choice in general for calyceal diverticula and specifically for posterior diverticula with thick layer of parenchyma surrounding with calculi >1.5 cm.
• Growing evidence for the effectiveness of LAP approach in cases of anterior diverticula, diverticula covered with thin layer, diverticula containing large calculi or large diverticula.