VII-37 and VII-38. The answers are D and B, respectively. This patient has a typical clinical, laboratory, and radiologic presentation of nephrolithiasis. The CT shows a 10-mm obstructing calculus in the distal left ureter at the level of S1 and another 6-mm stone in the interpolar region of the left kidney. There is also left hydronephrosis and perinephric fat stranding. At present, there are no widely accepted, evidence-based guidelines for the evaluation and treatment of nephrolithiasis. The diagnosis is often made based on the history, physical examination, and urinalysis. Thus, it may not be necessary to wait for radiographic con!rmation before treating the symptoms. The diagnosis is con!rmed by an appropriate imaging study, preferably helical CT, which is highly sensitive, allows visualization of uric acid stones (traditionally considered “radiolucent”), and is able to avoid radiocontrast. Helical CT detects stones as small as 1 mm that may be missed by other imaging modalities. Typically, helical CT reveals a ureteral stone or evidence of recent passage (e.g., perinephric stranding or hydronephrosis), whereas a plain abdominal radiograph (kidney/ureter/bladder, or KUB) can miss a stone in the ureter or kidney, even if it is radiopaque, and does not provide information on obstruction. Abdominal ultrasound o#ers the advantage of avoiding radiation and provides information on hydronephrosis, but it is not as sensitive as CT and images only the kidney and possibly the proximal segment of the ureter; thus most ureteral stones are not detectable by ultrasound. Urologic intervention, such as cystoscopy, should be postponed unless there is evidence of a urinary tract infection (UTI), a low probability of spontaneous stone passage (e.g., a stone measuring ≥6 mm or an anatomic abnormality), or intractable pain. A ureteral stent may be placed cystoscopically, but this procedure typically requires general anesthesia, and the stent can be quite uncomfortable, may cause gross hematuria, and may increase the risk of UTI. Many patients who experience their !rst episode of colic seek emergent medical care. Randomized trials have demonstrated that parenterally administered NSAIDs (such as ketorolac) are just as e#ective as opioids in relieving symptoms and have fewer side e#ects. Excessive $uid administration has not been shown to be bene!cial; therefore, the goal should be to maintain euvolemia. Use of an α-blocker may increase the rate of spontaneous stone passage.
