Urolithiasis (Kidney Stones)

Symptoms

• Sudden severe colicky flank pain radiating to groin/testicle/labia
• Patient writhing, unable to find comfortable position (contrast with peritonitis where patients lie still)
• Nausea and vomiting
• Dysuria, urinary frequency/urgency if stone in distal ureter near bladder
• Gross hematuria in 30-40%, microscopic in ~85%

Signs / physical exam

• CVA tenderness (often mild despite severe pain)
• Patient appears restless and uncomfortable
• Vital signs may show mild tachycardia, hypertension from pain
• Fever raises concern for obstructed infected system (urologic emergency)

Classic findings

Writhing patient with acute severe flank pain radiating to groin + hematuria = textbook ureteral stone.

Diagnostic criteria

CT-confirmed urinary tract calculus with consistent clinical presentation. Size and location predict spontaneous passage: <5 mm pass ~80%, 5-10 mm ~50%, >10 mm rarely; distal ureteral stones pass more often than proximal.

Labs

• Urinalysis with microscopy — hematuria (gross or microscopic), pH (acidic favors uric acid; alkaline favors struvite, calcium phosphate), crystals
• Urine culture if pyuria or fever
• BMP — Ca, creatinine, electrolytes
• CBC — leukocytosis suggests infection
• Beta-hCG in women of reproductive age (before imaging)
• Stone analysis when stone retrieved
• Metabolic workup (24-h urine for Ca, oxalate, citrate, uric acid, Na, volume) for recurrent stones, single kidney, or first stone in child

Imaging

• Non-contrast CT abdomen/pelvis (low-dose) — gold standard; identifies stones >1 mm, hydronephrosis, alternative diagnoses
• Renal ultrasound — first-line in pregnancy and children; reasonable initial test in adults to detect hydronephrosis (lower sensitivity for small ureteral stones)
• KUB plain film — limited; misses radiolucent uric acid stones
• MR urography — alternative in pregnancy when US insufficient

First-line

• Pain control — NSAIDs (ketorolac IV/IM, ibuprofen) are first-line; superior to opioids and reduce ureteral spasm; AVOID in CKD, dehydration, or single kidney
• Opioids (morphine, hydromorphone) as second-line or adjunctive analgesia
• Antiemetics (ondansetron, metoclopramide)
• IV fluids only if dehydrated — aggressive forced diuresis does not promote passage
• Medical expulsive therapy (MET): alpha-blocker — tamsulosin 0.4 mg daily — for ureteral stones 5-10 mm; modest benefit

Second-line / adjunct

• Urgent urologic intervention (within 24-48 h) if: obstructed infected system (urosepsis), single kidney with obstruction, refractory pain/vomiting, AKI from obstruction
• Percutaneous nephrostomy or ureteral stent for emergent decompression
• Definitive treatment options: shock wave lithotripsy (SWL) for stones <2 cm, ureteroscopy with laser lithotripsy (preferred for distal/large stones), percutaneous nephrolithotomy (PCNL) for staghorn or >2 cm renal stones
• Prevention strategies based on stone type:
• Calcium stones: high fluid intake (>2.5 L/day urine output), normal dietary calcium, low sodium, low animal protein, thiazide (HCTZ, chlorthalidone, indapamide) for hypercalciuria, potassium citrate for hypocitraturia
• Uric acid stones: alkalinize urine (potassium citrate to pH 6.5-7), allopurinol if hyperuricosuria
• Cystine stones: aggressive hydration, alkalinization, tiopronin or D-penicillamine for refractory
• Struvite stones: complete stone removal + treat infection (urease inhibitor acetohydroxamic acid in select cases)