The spontaneous passage rate for ureteral stone less than 1cm causing acute ureteral obstruction is about 50%. Previous Cochrane review has concluded that alpha blocker is likely to increase stone passage rate, reduce time to stone passage, analgesic use and hospitalisations. The European Association of Urology Guideline also recommends giving alpha blockers as Medical Expulsive Therapy to patients with distal ureteric stones >5mm. However there is heterogeneity in different alpha blockers.

Silodosin is a recently introduced selective alpha blocker which has a much higher selectivity for the alpha-1-A receptor (17-fold compared with tamsulosin). From previous animal studies, ureteral contraction is mainly mediated by the alpha-1-A receptor, hence silodosin maybe more effective in increasing stone passage compared with tamsulosin.

Previous studies and meta-analysis has shown superiority of silodosin over tamsulosin on earlier stone passage and less pain. However, there is no data on Chinese population.

The investigators would like to compare the efficacy and side effect profile of Silodosin versus tamsulosin on improving stone passage rate and hence reduce rate of further intervention for stone clearance.

Inclusion criteria:

• Presented with radio-opaque ureteric stone of size 5mm to 10mm on KUB
• Patients who can understand the study protocol and comply with the followup schedule

Exclusion criteria:

• Radiolucent stone
• Paper thin cortex
• Non-functioning kidney
• Renal insufficiency (serum creatinine greater than 1.8 mg/dl or 160umol/dL)
• Concurrent urosepsis
• Current [alpha]-blocker usage, Ca channel blocker, steroid
• Pregnancy
• Age < 18
• History of ureteral stricture
• History of ureteric stone treatment within 2 years
• Allergic reaction to the study medication
• Unable to Consent
• Patient on JJ stent or PCN drainage