1. Renal calculi

Kidney stones refer to solid crystalline minerals or salt deposits formed within the kidneys, representing the most common type of urinary stones. Characterized by the crystallization of stone-forming substances due to metabolic or environmental factors, kidney stones are solid structures that can lead to urinary tract obstruction, infections, and kidney damage. Their prevention and management require a combination of analysis of underlying causes, lifestyle modifications, and targeted treatments.

2. Ureteral calculi

Ureteral stones refer to calculi located in the ureter (a narrow tube connecting the kidneys to the bladder). They are most commonly caused by kidney stones that migrate downward and become lodged in the ureter, while a minority originate primarily within the ureter itself.

3. Staghorn Calculus 

Staghorn Calculus refers to a cast-shaped stone that partially or completely fills the renal pelvis and extends into the renal calyces, named for its antler-like morphology. It is classified into two types based on anatomical involvement: 1) Partial Staghorn Calculus (Occupies the renal pelvis and extends into ≥2 calyces); 2) Complete Staghorn Calculus (Fills the entire renal pelvis with extensions into all calyces, forming a complete cast of the collecting system)

4. Impacted Calculus 

Impacted Calculus refers to a pathological condition characterized by the fixed retention of a stone within the urinary tract for ≥6 weeks, inducing localized mucosal edema, polypoid encapsulation of the calculus, and proximal urinary tract dilation. This state is often confirmed by imaging features such as the "soft-tissue rim sign" on CT scans, indicating chronic inflammatory changes around the stone.

5. Renal Crystalluria 

Renal Crystalluria refers to the precipitation of microcrystals (5-500 μm in diameter) from supersaturated solutes in urine, representing the initial pathological stage of renal calculi formation. These microcrystals, when combined with organic matrix substances like Tamm-Horsfall protein, may further aggregate into clinically significant stones.

6. Hydronephrosis 

Hydronephrosis is a pathological condition characterized by elevated intraluminal pressure and progressive dilation of the renal pelvis and calyces due to urinary tract obstruction. Its formation mechanisms include mechanical obstruction (e.g., stones, strictures), functional obstruction (e.g., neurogenic bladder, aperistaltic ureter), and reflux-related dilation (e.g., vesicoureteral reflux). This tripartite classification guides targeted diagnostic and therapeutic interventions.

7. Cystine Stone 

A type of urinary tract stone caused by the autosomal recessive genetic disorder cystinuria, characterized by impaired renal tubular reabsorption of cystine. This leads to supersaturation and crystallization of cystine in urine, forming pale yellow, hexagonal crystals with a soft texture. Radiographically, these stones are poorly radiopaque, with a CT attenuation value of approximately 400-600 Hounsfield units (HU). Patients with untreated cystinuria have a 10-year recurrence rate approaching 100%.