Urolithiasis, disorders of the urinary tract and bladder

Urolithiasis is the presence of concretions (stones) in the urinary tract – in the renal pelvis (nephrolithiasis), ureter (ureterolithiasis), urinary bladder (cystolithiasis), or urethra (urethrolithiasis), or stone-forming substances in the renal parenchyma (nephrocalcinosis). In our population, the most common type is calcium oxalate stones.

Pathogenesis[edit | edit source]

Crystal formation and aggregation

Main causes include:

Supersaturation of urine with stone-forming substances (Ca²⁺, urates, oxalate), promoted by reduced urine output (low diuresis)
Urinary stasis (obstructive uropathy)
Changes in urine pH (including bacteria that break down urea – Proteus, Pseudomonas, Klebsiella → struvite lithiasis)
Deficiency of crystallization and aggregation inhibitors (citrates, pyrophosphates, Mg²⁺, glycoproteins)
Certain drugs (sulfonamides, antacids)

Cystolithiasis develops due to chronic urinary retention in subvesical obstruction or neurogenic bladder.

Types of stones[edit | edit source]

Radiopaque (visible on X-ray):
- Calcium oxalate
- Calcium phosphate
- Struvite (MgNH₄PO₄)
- Cystine stones
Radiolucent (not visible on X-ray):
- Uric acid stones
- Xanthine stones

Clinical presentation[edit | edit source]

Urolithiasis may be asymptomatic (non-moving stones).

Depending on location:

Nephrolithiasis: dull kidney pain (tenderness, positive tapping pain), possibly colic if urine outflow is blocked
Ureterolithiasis: renal colic with autonomic symptoms; pain radiates depending on location (back, inner thigh)
Cystolithiasis: suprapubic pain, frequent urination (pollakisuria), urgency

Often accompanied by hematuria and complications such as infections (pyelonephritis, cystitis)

Complications[edit | edit source]

Obstruction → renal colic, hydronephrosis
Infection → up to urosepsis
Bleeding
Renal failure (especially if bilateral obstruction)

Diagnostics[edit | edit source]

Urine:

Sediment examination
Chemical analysis (including cystine)
pH, density
Culture (may be negative in complete obstruction)

Blood:

Ca²⁺, phosphate, uric acid
Acid-base status (to rule out RTA – renal tubular acidosis)

Stone analysis:

Chemical analysis
Mineralography (polarized microscopy, X-ray diffraction)

Imaging:

Ultrasound – stones + dilation of urinary tract, acoustic shadow
X-ray (KUB, excretory urography)
Cystography (for bladder stones)
Cystoscopy
Spiral CT
DMSA scan (functional kidney study)

Metabolic disorders associated:

Hypercalcemia → hyperparathyroidism
Hypercalciuria (absorptive or renal type)
Hyperoxaluria (fat malabsorption: chronic pancreatitis, obstructive jaundice)
Hyperuricosuria (myeloproliferative diseases, purine disorders, chemotherapy)
Hypercystinuria (genetic transport defect)
Hypocitraturia (chronic diarrhea, thiazides)

Metabolic evaluation[edit | edit source]

Serum:

Urea, creatinine, uric acid
Electrolytes (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, phosphate)
Glucose, proteins, liver tests, lipids

24-hour urine:

Volume, pH
Excretion of phosphate, uric acid, creatinine
Electrolytes and oxalates, citrates, sulfates

Calculations:

Creatinine clearance
Uric acid clearance
Ca²⁺/creatinine ratio, Ca²⁺/Mg²⁺ ratio
Proteinuria

Diet testing:

Low-calcium diet followed by 1000 mg oral calcium tablets

Differential diagnosis[edit | edit source]

Acute abdomen
Biliary colic
Gynecological conditions
Tumor, UTI, coagulopathy (hematuria causes)
Urothelial tumor (filling defect)
Phlebolith (on imaging)

Treatment[edit | edit source]

Acute renal colic:[edit | edit source]

Analgesics
Spasmolytics
NSAIDs (e.g., indomethacin)
Hydration
Urinary diversion (if infection or sepsis)

Chronic urolithiasis:[edit | edit source]

Endoscopic procedures
Instrumentation:
- Nephrostomy
- Ureteral stenting and stone extraction
- Cystoscopic extraction or fragmentation
Extracorporeal shock wave lithotripsy (ESWL)
Open surgery (rare ~1%): lithotomy, nephrotomy, nephrectomy

Stone extraction tools:

Forceps
Zeiss loop
Dormia basket

Stone fragmentation:

Mechanical
Ultrasound
Electrohydraulic
Laser

Indications for lithotripsy[edit | edit source]

Radiopaque stones <2 cm, soft composition, good anatomy and drainage
2 cm or hard stones or poor anatomy → alternative methods
Radiolucent stones → difficult targeting
Small asymptomatic stones:
- ≤4 mm ureteral stones → conservative management