A 32-year-old woman, previously healthy, presents with 2 days of right flank pain radiating to the right groin. She denies any dysuria, urgency, frequency, or fever and has no history of nephrolithiasis. Her pain is fairly well controlled on a regimen of 220 mg of naproxen twice daily, and she is taking no other medications. Computed tomography by the kidney stone protocol shows a 5-mm calculus at the right ureterovesical junction.
Urinalysis, 4 to 10 red blood cells per high-power field
Urine Gram stain and culture, negative
Serum creatinine, 1.0 mg/dL
A 5-mm calculus in the distal ureter has about a 50% to 60% chance of spontaneous passage and, in the absence of infection, renal failure, or unmanageable pain, may be managed conservatively for up to 4 weeks. However, the average time to passage in some studies is as long as 22 days, and thus it is reasonable to use “medical expulsive therapy” to expedite resolution. Both ?-blockers and calcium channel blockers have been shown to inhibit the contraction of the smooth muscle responsible for ureteral spasms (while still allowing antegrade stone propagation). The agent that has been most studied in this setting is tamsulosin, generally in a dosage of 0.4 mg/d given for as long as 1 month.3 In a recent meta-analysis of 9 randomized trials of this agent vs placebo in patients referred to urology clinics for moderate-sized ureteral stones (5-7 mm in diameter), stones passed an average of 2 to 6 days earlier in the treatment group. In these trials, the mean time to stone expulsion was less than 14 days (including the upper bound of the 95% confidence interval). Nifedipine, the only calcium channel blocker that has been systematically evaluated, appears to be slightly less effective than tamsulosin.