Staghorn calculi refer to branched stones that fill all or part of the renal pelvis and branch into several or all of the calyces. They are most often composed of struvite (magnesium ammonium phosphate) and/or calcium carbonate apatite. These stones are often referred to as 'infection stones' since they are strongly associated with urinary tract infections with urea splitting organisms. Cystine stones, although much less common, may also develop into staghorn calculi . (See "Cystine stones".)
Small struvite and/or calcium carbonate apatite stones can grow rapidly over a period of weeks to months into large staghorn calculi involving the calyces and entire renal pelvis. If left untreated, this can lead to deterioration of kidney function and end-stage renal disease . In addition, since the stones often remain infected, there is a risk of developing sepsis . Thus, most patients require definitive surgical treatment.
There are several alternative surgical treatments for staghorn calculi. The American Urological Association Nephrolithiasis Guidelines Panel reviewed the existing literature to determine the optimal application of these different treatment modalities [3,4]. The current discussion is largely based on this Panel's recommendations for the management of staghorn calculi; the pathogenesis and clinical manifestations of struvite stones as well as the management of renal and ureteral calculi in general, are presented separately. (See "Pathogenesis and clinical manifestations of struvite stones" and "Options in the management of renal and ureteral stones in adults".)
Limitations of the data — There are limitations that must be considered when interpreting and adopting guidelines for the optimal treatment of staghorn calculi :
- Data from randomized controlled studies comparing treatment options are very limited.
- There is no uniform system of categorizing staghorn calculi, no standard method of describing the collecting system, and no widely accepted system of reporting the size of staghorn calculi.
- The indications for hospitalization may vary in different countries.