Pathophysiology of kidney stone formation and management of staghorn calculus
Stones form in the kidneys by crystallization of salts excreted in the urine, usually calcium oxalate or uric acid. Chronic kidney infection also causes stone formation. Most of the time it is because of both crystallization and infection. Stones begin as a small spicule in the beginnings of the collecting system called renal papilla. These calcium deposits are called as Randall’s plagues. Over these spicules layering of stone material happens over and over again for months to years causing the stones to grow. Lucky are those persons when the stone drops from their attachment at the papilla and move further down the calyx, infundibulum, and pelvis into the ureter. Once the stone is stuck in the ureter it causes severe pain and the treatment is straightforward and relatively easy. But the stones which are not dropping down tend to grow to large size without causing much pain (Silent Stones), filling the entire collecting system. These stones are called as “staghorn” calculi. These stone are associated with gradual loss of kidney function over months and years. When both the kidneys are affected patient suffers from renal failure. Managing these patients require a combination of procedures and in stages to save the kidney from further damage and clear the stones. For the first step in the prevention of stone recurrence is complete stone clearance. Small stone left in the kidney will act as a nidus and promote stone growth over it. The stag horn calculus usually has a large pelvic component which is cleared by PCNL (Percutaneous nephrolithotomy and the smaller components in the calyces are managed with RIRS (Retro-grade intrarenal surgery).