This study will compare L-citrulline and tamsulosin as medical expulsive therapy for adults with single distal ureteral stones.

Eligible participants with a single distal ureteral stone measuring 5 to 10 mm will be randomly assigned to receive either oral L-citrulline 750 mg twice daily or oral tamsulosin 0.4 mg once daily. Treatment will continue until documented stone passage or completion of 4 weeks of therapy, whichever occurs first.

Participants will be followed weekly for up to 4 weeks. The main outcome is stone expulsion within 4 weeks. The study will also assess time to stone expulsion, pain episodes, analgesic use, need for additional intervention, and adverse events.

This is a prospective, randomized, controlled trial conducted at the outpatient Urology Clinic, Beni-Suef University Hospital.

The study will include adult patients aged 18 to 60 years with a single distal ureteral stone measuring 5 to 10 mm, normal renal function, and controlled pain. Patients with fever or active urinary tract infection, severe hydronephrosis, solitary kidney, pregnancy, previous ureteric surgery, multiple stones, or an indication for urgent surgical intervention will be excluded.

Eligible participants will be randomized in a 1:1 ratio to one of two treatment groups. The L-citrulline group will receive oral L-citrulline 750 mg twice daily. The tamsulosin group will receive oral tamsulosin 0.4 mg once daily. Treatment will be discontinued upon stone passage or after completion of 4 weeks of therapy, whichever occurs first. Both groups will receive standard supportive care, including analgesics as needed, hydration advice, and use of a stone strainer.

Participants will be evaluated weekly for 4 weeks. Follow-up assessments will include symptom review, pain assessment using the Visual Analog Scale, documentation of pain episodes, analgesic requirements, adverse event monitoring, and imaging assessment using ultrasound with or without KUB, with low-dose computed tomography when clinically needed.

The primary outcome is stone expulsion rate within 4 weeks. Stone expulsion will be confirmed by patient-reported stone passage with stone capture, or by absence of the stone on follow-up imaging. Secondary outcomes include time to stone expulsion, number of pain episodes, analgesic use, need for additional intervention such as ureteroscopy or ureteral stenting, and adverse events.

Inclusion Criteria:

• Adults aged 18 to 60 years.
• Single distal ureteral stone.
• Stone size 5 to 10 mm.
• Normal renal function.
• Controlled pain.
• Willingness to comply with follow-up for 4 weeks.
• Written informed consent.

Exclusion Criteria:

• Fever or active urinary tract infection.
• Severe hydronephrosis.
• Solitary kidney.
• Pregnancy.
• Previous ureteric surgery.
• Multiple ureteral stones.
• Indication for urgent surgical intervention.
• Known hypersensitivity or contraindication to L-citrulline or tamsulosin.
• Inability to complete follow-up.

Individual participant data will not be shared because the study is an investigator-initiated single-center clinical trial and the informed consent does not include a specific plan for external individual-level data sharing. Only aggregated, de-identified study results will be reported. Any future sharing of de-identified individual participant data would require additional approval from the Research Ethics Committee.

The study will use a double-dummy design. Participants in each group will receive one active treatment and one matched placebo to maintain blinding. Participants, care providers, investigators, and outcomes assessors will remain blinded to treatment allocation.