A 48-year-old woman sought medical attention after an episode of gross hematuria associated with mild right-sided loin discomfort. She did not have urinary frequency, urgency, or dysuria. Her history included 3 urinary tract infections; a Proteus species was cultured on each occasion. The family history was unremarkable. Other than mild loin tenderness, physical findings were normal.
Urinalysis showed 5 to 10 white blood cells and 3 to 5 red blood cells per high-power field. Urine culture was negative. Plain radiography with a kidney-ureter-bladder (KUB) view revealed multiple opacities in the region of both kidneys and specifically in a location that corresponded to each renal pelvis (Figure 1A). A subsequent intravenous urogram (IVU) confirmed the presence of bilateral renal staghorn calculi and a right ureteral stone within a ureterocele. A radioisotopic study showed the differential function of the right and left kidneys to be 44% and 56%, respectively, with scarring in the upper pole of the right kidney. Serum calcium, phosphate, urate, blood urea nitrogen, creatinine, and electrolyte levels were normal.
The patient underwent transurethral incision of the right ureterocele and ureteroscopic removal of the ureteral stone. Simultaneous right percutaneous nephrolithotomy (PCNL) was performed, and a ureteral stent was inserted at the end of the procedure (Figure 1B). Second stage right PCNL for the residual stones was performed 2 weeks later, and all the stones were cleared (Figure 1C). Left PCNL was also performed with clearance of all the residual stones (Figure 1D). Stone analysis revealed that the calculi were composed of 76% magnesium ammonium phosphate (struvite) and 24% calcium carbonate apatite.
RENAL STONES: AN OVERVIEW
Urolithiasis affects about 10% to 12% of the population worldwide, and the incidence is increasing.1,2 Without preventative intervention, up to 50% of patients have a recurrence within 5 years after successful treatment. Males and those with a family history of renal stones are more likely to be affected. Staghorn stones are slightly more common in females.3
Staghorn calculi are branched stones that occupy a major part of the renal collecting system.4 These stones usually fill the renal pelvis and branch into several or all of the calices. Most staghorn stones are composed of mixtures of magnesium ammonium phosphate and calcium carbonate apatite, but cystine and uric acid stones can also present in this fashion.3
Staghorn stones composed of struvite are usually associated with urinary tract infection caused by a urea-splitting organism, the most common of which is Proteus mirabilis. Other urea-splitting bacteria include some Klebsiella and Pseudomonas species, Staphylococcus saprophyticus, and Ureaplasma urealyticum. The resultant alkaline urinary environment and the high urinary concentrations of ammonia, trivalent phosphate, and magnesium promote crystallization of magnesium ammonium phosphate, which leads to the formation of large, branched stones.4 Magnesium ammonium phosphate stones can form on a idus of a calcium oxalate renal stone.
Renal stones are often asymptomatic. In contrast to ureteral stones, renal stones seldom present as an emergency. Typical symptoms of acute renal colic are intermittent colicky flank pain that might radiate to the lower abdomen or groin.5 Nausea and vomiting may be present.
The physical examination findings are either unremarkable or reveal mild tenderness with palpation of the affected kidney. Patients who have renal stones complicated by pyelonephritis are often febrile and toxic-looking and have tachycardia. In this setting, the tenderness with palpation of the affected kidney is usually considerable.
1. Lotan Y, Cadeddu JA, Pearle MS. International comparison of cost effectiveness of medical management strategies for nephrolithiasis. Urol Res. 2005;33:223-230.
2. Robertson WG. Is prevention of stone recurrence financially worthwhile? Urol Res. 2006;34:157-161.
3. Akagashi K, Tanda H, Kato S, et al. Characteristics of patients with staghorn calculi in our experience. Int J Urol. 2004;11:276-281.
4. Preminger GM, Assimos DG, Lingeman JE, et al. Chapter 1: AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations. J Urol. 2005;173:1991-2000.
5. Miller NL, Lingeman JE. Management of kidney stones. BMJ. 2007;334:468-472.
6. Leung AK, Robson WL. Urinary tract infection in infancy and childhood. Adv Pediatr. 1991;38: 257-285.
7. Smith RC, Verga M, McCarthy S, et al. Diagnosis of acute flank pain: value of unenhanced helical CT. AJR. 1996;166:97-101.
8. Niall O, Russell J, MacGregor R, et al. A comparison of noncontrast computerized tomography with excretory urography in the assessment of acute flank pain. J Urol. 1999;161:534-537.
9. Blandy JP, Singh M. The case for a more aggressive approach to staghorn stones. J Urol. 1976;115: 505-506.
10. Murshidi MS. Simple radiological indicators for staghorn calculi response to ESWL. Int Urol Nephrol. 2006;38:69-73.
11. El-Assmy A, El-Nahas A, Madbouly K. Extracorporeal shock-wave lithotripsy monotherapy of partial staghorn calculi: prognostic factors and longterm clinical results. Scand J Urol Nephrol. 2006;40: 320-325.
12. Krambeck AE, Gettman MT, Rohlinger AL, et al. Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of followup. J Urol. 2006;175:1742-1747.
13. Pearle MS, Lingeman JE, Leveillee R, et al. Prospective, randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less. J Urol. 2005;173:2005-2009.
14. Knoll T, Alken P, Michel MS. Progress in management of ureteric stones. EAU Updates Series. 2005;3:44-50.
15. Al-Kohlany KM, Shokeir AA, Mosbah A, et al. Treatment of complete staghorn stones: a prospective randomized comparison of open surgery versus percutaneous nephrolithotomy. J Urol. 2005;173: 469-473.
16. Brannen GE, Bush WH, Correa RJ, et al. Kidney stone removal: percutaneous versus surgical lithotomy. J Urol. 1985;133:6-12.
17. Tiselius HG, Ackermann D, Alken P, et al. Guidelines on urolithiasis. Eur Urol. 2001;40:362-371.
18. Teichman JM. Acute renal colic from ureteral calculus. N Engl J Med. 2004;350:684-693.
19. Micali S, Grande M, Sighinolfi MC, et al. Medical therapy of urolithiasis. J Endourol. 2006;20: 841-847.
20. Westenberg A, Harper M, Zafirakis H, et al. Bladder and renal stones: management and treatment. Hosp Med. 2002;63:34-41.