A 52-year-old man from Delhi presents with acute left flank pain and hematuria for 6 hours. He has a history of recurrent kidney stones. On examination, he is afebrile, BP 140/90 mmHg, and has left costovertebral angle tenderness. Non-contrast CT (NCCT) abdomen shows a 6 mm stone in the left ureter at the level of the pelvic brim with mild hydronephrosis. What is the most likely outcome if conservative management is chosen?

Explanation

## Stone Passage Prediction Based on Size and Location **Key Point:** Stone size is the strongest predictor of spontaneous passage in uncomplicated ureterolithiasis. Stones <6 mm have a >90% passage rate within 4 weeks, while stones 6–10 mm have a 50% passage rate. **Clinical Pearl:** The pelvic brim location (at the level of iliac vessels) is one of the three physiologic narrowing points of the ureter. Despite this, small stones at this site still have excellent passage rates if there is no obstruction, infection, or renal insufficiency. **High-Yield:** In uncomplicated unilateral ureteral stones <10 mm with normal renal function and no fever, conservative management (hydration, analgesia, antiemetics) is the standard of care. The patient should be counseled that passage typically occurs within 2–4 weeks. ### Why Conservative Management Works 1. Stone size 6 mm is at the threshold for spontaneous passage 2. No fever, normal renal function, unilateral obstruction 3. Mild hydronephrosis is expected and resolves with stone passage 4. Pain control and expectant management reduce morbidity **Tip:** Remember the "6-10-20" rule: stones <6 mm pass in >90% of cases, 6–10 mm in ~50%, and >20 mm in <10%.