eMedicine Specialties > Urology > Stones

Struvite and Staghorn Calculi: Workup

Author: Maxwell Meng, MD, Associate Professor-in-Residence, Department of Urology, University of California at San Francisco
Coauthor(s): Marshall L Stoller, MD, Medical Director of Urinary Stone Center, Professor, Department of Urology, University of California at San Francisco; Thomas Minor, MD, Resident, Department of Urology, University of California San Francisco
Contributor Information and Disclosures

Updated: Nov 24, 2009

Workup

Laboratory Studies

  • Prior to treatment of struvite stones, complete serum laboratory studies are required, including complete blood cell count, prothrombin and activated partial thromboplastin times, serum electrolyte evaluations, and creatinine measurements.
    • Chronic anemia may necessitate preoperative blood typing and screening for potential blood transfusion, especially if open or percutaneous surgery is planned.
    • More importantly, urinalysis and urine culture should be performed several days before surgery, and specific antibiotic therapy should be initiated at least 24 hours prior to treatment. Findings from cultures of voided urine may not accurately reflect renal microbiology, with a negative culture finding or discrepant organisms.
    • Additional aspects of the metabolic evaluation of urinary stones should be pursued because up to 50% of patients with infection-related stones have concomitant metabolic abnormalities. Thus, a 24-hour urinary collection (for calcium, oxalate, uric acid, citrate, phosphate, uric acid, magnesium, sodium, total volume, and pH) and simultaneous serum tests for calcium, uric acid, electrolytes, and phosphate are indicated. If the serum calcium level is elevated, it should be rechecked along with serum parathyroid hormone levels.
    • If the patient has undergone prior stone removal surgery, information regarding the chemical composition of any previous stones is extremely important.

Imaging Studies

  • Plain abdominal radiography usually documents the extent of struvite staghorn calculi; however, additional imaging tests that reveal the anatomy of the renal collecting system can be helpful.
  • Intravenous urography can clearly delineate the pelvic calyceal anatomy, although, currently, noncontrast CT scanning followed by intravenous contrast CT scanning is obtained most often in the evaluation of urinary stones. CT scans also display the adjacent structures and may aid in selecting the safest percutaneous tract to access the renal collecting system.  
    • Narrow, scarred infundibula indicate the need for percutaneous nephrostomy (PCN), while wide, large renal infundibula suggest that extracorporeal shockwave lithotripsy (ESWL) might be adequate. If the passageway between the calyces and renal pelvis is open and unrestricted, stone fragments produced during ESWL are much more likely to pass.
    • Traditionally, staghorn calculi were defined as partial if the renal pelvic stone extended into at least 2 calyceal groups or complete if at least 80% of the collecting system was filled. Some experts argue that, to compare published stone-free rates, especially in the era of minimally invasive modalities, an improved classification system based on stone size should be implemented. CT scanning with 3-dimensional reconstruction offers accurate stone volumes, but the added radiographic analysis is costly, time consuming, and neither practical nor readily available. Lam and associates reported a simple 2-dimensional electronic computerized tracing technique that calculated stone surface area, which correlated well against stone volume.5
  • Performing nuclear renography is not necessary, but findings are helpful for determining the relative function of the affected kidney. If the kidney has minimal function, nephrectomy may be needed. However, overall and relative renal function must be considered prior to removal of the kidney.
  • Ultrasonography alone is insufficient, but images show coexisting hydronephrosis.
  • MRI does not help visualize urinary calculi; therefore, this modality has no role in preoperative and postoperative imaging of struvite stones.

More on Struvite and Staghorn Calculi

Overview: Struvite and Staghorn Calculi
Workup: Struvite and Staghorn Calculi
Treatment: Struvite and Staghorn Calculi
Follow-up: Struvite and Staghorn Calculi
Multimedia: Struvite and Staghorn Calculi
References
Further Reading
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References

  1. Brown TR. On the Relation Between the Variety of Microorganisms and the Composition of Stone in Calculous Pyelonephritis. JAMA. 1901;36:1394-7.

  2. Sumner JB. The Isolation and Crystallization of the Enzyme Urease. J Biol Chem. 1926;69:435-41.

  3. Priestley JT, Dunn JH. Branched renal calculi. J Urol. Feb 1949;61(2):194-203. [Medline].

  4. Ansari MS, Gupta NP, Hemal AK, Dogra PN, Seth A, Aron M, et al. Spectrum of stone composition: structural analysis of 1050 upper urinary tract calculi from northern India. Int J Urol. Jan 2005;12(1):12-6. [Medline].

  5. Lam HS, Lingeman JE, Russo R, Chua GT. Stone surface area determination techniques: a unifying concept of staghorn stone burden assessment. J Urol. Sep 1992;148(3 Pt 2):1026-9. [Medline].

  6. Lewis GA, Schuster GA, Cooper RA. Dissolution of renal calculi with dicloxacillin. Urology. Oct 1983;22(4):401-3. [Medline].

  7. Al-Kohlany KM, Shokeir AA, Mosbah A, Mohsen T, Shoma AM, Eraky I, et al. Treatment of complete staghorn stones: a prospective randomized comparison of open surgery versus percutaneous nephrolithotomy. J Urol. Feb 2005;173(2):469-73. [Medline].

  8. Meretyk S, Gofrit ON, Gafni O, Pode D, Shapiro A, Verstandig A, et al. Complete staghorn calculi: random prospective comparison between extracorporeal shock wave lithotripsy monotherapy and combined with percutaneous nephrostolithotomy. J Urol. Mar 1997;157(3):780-6. [Medline].

  9. Gleason MJ, Griffith DP. Infection Stones. In: Resnick MI, Pak CY, eds. Urolithiasis: a Medical and Surgical Reference. Philadelphia, Pa: WB Saunders; 1990:134-6.

  10. Griffith DP, Osborne CA. Infection (urease) stones. Miner Electrolyte Metab. 1987;13(4):278-85. [Medline].

  11. Lam HS, Lingeman JE, Mosbaugh PG, Steele RE, Knapp PM, Scott JW, et al. Evolution of the technique of combination therapy for staghorn calculi: a decreasing role for extracorporeal shock wave lithotripsy. J Urol. Sep 1992;148(3 Pt 2):1058-62. [Medline].

  12. Lingeman JE, Lifshitz DA, Evan AP. Surgical management of urinary lithiasis. In: Walsh PC, Retik AB, Vaughan ED, Wein AJ, eds. Campbell's Urology. Vol 4. 8th ed. Philadelphia, Pa: WB Saunders; 2002:3366-3370.

  13. McDougall EM, Liatsikos EN, Dinlenc CZ. Percutaneous approaches to the Upper Urinary Tract. In: Walsh PC, Retik AB, Vaughan ED, Wein AJ, eds. Campbell's Urology. Vol 4. 8th ed. Philadelphia, Pa: WB Saunders; 2002:3320-40.

  14. Morey AF, Nitahara KS, McAninch JW. Modified anatrophic nephrolithotomy for management of staghorn calculi: is renal function preserved?. J Urol. Sep 1999;162(3 Pt 1):670-3. [Medline].

  15. Schwartz BF, Stoller ML. Nonsurgical management of infection-related renal calculi. Urol Clin North Am. Nov 1999;26(4):765-78, viii. [Medline].

  16. [Guideline] Segura JW, Preminger GM, Assimos DG, Dretler SP, Kahn RI, Lingeman JE, et al. Nephrolithiasis Clinical Guidelines Panel summary report on the management of staghorn calculi. The American Urological Association Nephrolithiasis Clinical Guidelines Panel. J Urol. Jun 1994;151(6):1648-51. [Medline].

  17. Suby HI, Albright F. Dissolution of Phosphatic Urinary Calculi by the Retrograde Introduction of a Citrate Solution Containing Magnesium. N Engl J Med. 1943;228:81-91.

  18. Wang LP, Wong HY, Griffith DP. Treatment options in struvite stones. Urol Clin North Am. Feb 1997;24(1):149-62. [Medline].

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Further Reading

For further information, visit Medscape’s Stone Disease Resource Center.

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Keywords

struvite calculi, staghorn calculi, triple-phosphate stones, triple phosphate stones, infection stones, urease stones, magnesium-ammonium-phosphate stones, MAP stones, extracorporeal shock-wave lithotripsy, ESWL, percutaneous nephrolithotomy, PNL, kidney stones, infection stones, infection-induced stones, phosphatic stones, urea-splitting bacteria, urease-producing organisms, Ureaplasma urealyticum, U urealyticum, Proteus, Staphylococcus, Klebsiella, Providencia, Pseudomonas, staphylococci, urinary tract stones, urinary tract infection, UTI, staghorn stones, struvite stones, struvite calculus, staghorn calculus, lithogenesis, lithotripsy, nephrolithiasis

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Contributor Information and Disclosures

Author

Maxwell Meng, MD, Associate Professor-in-Residence, Department of Urology, University of California at San Francisco
Maxwell Meng, MD is a member of the following medical societies: American College of Surgeons, American Urological Association, and Society of Urologic Oncology
Disclosure: Nothing to disclose.

Coauthor(s)

Marshall L Stoller, MD, Medical Director of Urinary Stone Center, Professor, Department of Urology, University of California at San Francisco
Marshall L Stoller, MD is a member of the following medical societies: American Urological Association
Disclosure: Nothing to disclose.

Thomas Minor, MD, Resident, Department of Urology, University of California San Francisco
Thomas Minor, MD is a member of the following medical societies: American Urological Association
Disclosure: Nothing to disclose.

Medical Editor

Martha K Terris, MD, FACS, Professor, Department of Surgery, Medical College of Georgia
Martha K Terris, MD, FACS is a member of the following medical societies: American Cancer Society, American College of Surgeons, American Institute of Ultrasound in Medicine, American Urological Association, New York Academy of Sciences, and Society of University Urologists
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

CME Editor

J Stuart Wolf Jr, MD, FACS, David A Bloom Professor of Urology, Director of Division of Minimally Invasive Urology, Department of Urology, University of Michigan
J Stuart Wolf Jr, MD, FACS is a member of the following medical societies: American College of Surgeons, American Urological Association, Catholic Medical Association, Endourological Society, Society for Urology and Engineering, Society of Laparoendoscopic Surgeons, Society of University Urologists, and Society of Urologic Oncology
Disclosure: Terumo Corporation Consulting fee Consulting; Gyrus-ACMI Honoraria Speaking and teaching

Chief Editor

Bradley Fields Schwartz, DO, FACS, Professor of Urology, Director, Center for Laparoscopy and Endourology, Department of Surgery, Southern Illinois University School of Medicine
Bradley Fields Schwartz, DO, FACS is a member of the following medical societies: American College of Surgeons, American Urological Association, Association of Military Osteopathic Physicians and Surgeons, Endourological Society, Society of Laparoendoscopic Surgeons, and Society of University Urologists
Disclosure: Nothing to disclose.

 
 
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