Renal colic
Formal Definition
Severe, cramping flank pain caused by a ureteral stone obstructing urine flow from the kidney; characterized by colicky (waxing and waning) pain that radiates from the flank to the groin or genitalia, often accompanied by nausea, vomiting, and hematuria; diagnosed with non-contrast CT abdomen/pelvis (CT-KUB).
How It's Used on the Ward
"Kidney stone" or "they are passing a stone" — the agonizing flank pain that sends patients to the ED writhing unable to find a comfortable position.
Example
""28-year-old male with sudden-onset right flank pain radiating to the groin, unable to find a comfortable position, gross hematuria: classic renal colic. CT-KUB shows 4mm right proximal ureteral stone with mild hydronephrosis. Ketorolac IV, IV fluids, tamsulosin for medical expulsion therapy.""
Clinical Context
Stones <5mm: 90% pass spontaneously with hydration and analgesics. Stones 5–10mm: 50% pass, medical expulsion therapy (tamsulosin — alpha-blocker relaxes ureteral smooth muscle). Stones >10mm: urological intervention (ureteroscopy or shockwave lithotripsy). Pain management: NSAIDs (ketorolac) are first-line (superior to opioids in RCTs). Urgent urology for: fever + obstruction (infected obstructed kidney = urological emergency — needs emergent drainage), solitary kidney, bilateral obstruction, refractory pain/vomiting. Most common stone type: calcium oxalate (70%). Prevention: high fluid intake (>2.5L/day), dietary calcium (not restriction), low sodium, low animal protein. Straining urine to catch stone for analysis guides prevention.