eMedicine Specialties > Urology > Stones

Struvite and Staghorn Calculi: Follow-up

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

Outcome and Prognosis

Multiple measures of treatment outcomes are available for evaluation. At best, monotherapy ESWL for struvite staghorn stones yields stone-free rates of 60%. Residual fragments remain in 22-70% of patients, and re-treatment is necessary in 32-88% of patients.

In patients with a smaller stone burden (>500 mm2 surface area), stone-free rates may approach 90%. After monotherapy PNL, reported stone-free status is achieved in approximately 80% of patients. These outcomes are further improved in correlation to surgeon experience. Combining PNL with subsequent ESWL yields stone-free rates comparable to those of PNL alone; this likely reflects the aggressiveness of the initial PNL and attempts to remove residual stones via flexible nephroscopy.

While the goal of the physician is to ensure stone-free status, patients are interested in direct outcomes. Prevention of patient symptoms and associated stone-related morbidity, such as infection, are important means of assessing treatment success. Studies have demonstrated that, even in the presence of small stone fragments after ESWL monotherapy and perioperative antibiotics for 2 weeks, 86% of patients were cured of persistent infection. Conversely, achieving stone-free status does not ensure resolution of persistent urinary infections. Important considerations in these patients include anatomic abnormalities, neurogenic bladder, indwelling catheters, or urinary diversion. Long-term freedom from bacteriuria is probably not possible in these situations.

Potential deleterious effects of staghorn calculi and treatments for the stone have been a source of concern. However, studies have demonstrated the general safety of both ESWL and PNL in the management of large stones, even with a solitary kidney and chronic renal insufficiency. Effects of ESWL and PNL are minimal, with only slight decreases in renal function after intervention. Patients who progress to severe renal insufficiency associated with staghorn stones usually present initially with compromised renal function (serum creatinine level >3 mg/dL).

Future and Controversies

Many aspects of struvite staghorn calculi require further study.

Standardized classification of renal anatomy and staghorn calculi may improve staging of the stones. This will allow more accurate comparison of treatment modalities. Also, uniform methods of reporting treatment outcomes are needed.

Determining which endpoints (eg, stone free, clearance of infection, preservation of renal function, resolution of symptoms) are most important is necessary. Elucidating some of these factors will help in selecting the appropriate surgical approach and goals of intervention. Continued technological advancements in minimally invasive instruments and increasing worldwide surgical PNL experience will continue to lessen the morbidity associated with staghorn calculi therapy.

A better understanding of the etiology of infection staghorn stones may direct rational treatment. The potential role of microorganisms, such as nanobacteria, must be defined. In addition, development of more effective medical treatments may significantly alter management strategies. Urease inhibitors with less toxicity may have increased general utility. Also, drugs effective in acidification of the urine could halt stone formation and growth even in the presence of persistent infection.

 


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

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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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