Flexible ureteroscopy & Holmium laser (RIRS)

What is RIRS?

RIRS stands for Retrograde Intra-Renal Surgery. It describes flexible ureteroscopy performed all the way up into the kidney itself - as opposed to the rigid ureteroscopy used for lower-ureteric stones. A flexible ureteroscope can be steered into every calyx of the kidney, so stones in any location within the collecting system can be reached.

Dr Kooner has been performing pyeloscopy with laser lithotripsy for more than 20 years, using a high-powered Coherent Holmium laser with Moses technology, and his usual strategy is to combine laser lithotripsy with active extraction of fragments using a Dormia basket, rather than leaving dust and fragments to pass on their own.

When RIRS is the best option

• Kidney stones 5-20 mm of any composition or location, including lower-pole calyceal stones.
• Stones that are too dense for shockwave lithotripsy.
• Patients who cannot safely undergo ESWL (anticoagulation, aneurysm in the shockwave path, obesity, skeletal deformity).
• Patients with an intrarenal anatomy unfavourable for ESWL (narrow infundibular neck, long lower-pole axis).
• Stones that persist after previous ESWL.
• Cystine stones and other hard stone types.
• Patients on long-term anticoagulation.²

Outcomes

Stone-free rates after flexible ureteroscopy depend heavily on how "stone-free" is defined and on the clinical setting.^{3, 4}

• In specialised single-centre series, stone-free rates of around 80-93% have been reported for stones up to 2 cm - for example, a cohort of 110 patients with a mean stone burden of 27.5 mm reported 80.9% stone-free at four weeks, rising to 93.6% at three months.³
• In real-world multi-surgeon practice assessed on post-operative imaging, rates are lower: the MUSIC ROCKS registry of 6,487 ureteroscopies reported a complete stone-free rate of 49.6% for renal stones and 72.7% for ureteric stones, with adjusted surgeon-level rates ranging widely.⁴
• The figures an individual patient can expect depend on stone size, location (lower-pole stones are the most difficult), stone hardness, anatomy, and surgeon experience.

How the procedure is done

1. Access

   Under general anaesthetic, a flexible ureteroscope is passed up the ureter into the kidney. Sometimes a ureteral access sheath is placed first to protect the ureter and allow multiple passes.

2. Laser lithotripsy

   The Holmium:YAG laser is delivered down the working channel to fragment the stone. High-powered laser settings allow efficient fragmentation; Moses technology optimises the energy delivery.

3. Fragment retrieval

   Fragments are removed using a Dormia basket wherever possible, rather than leaving them to pass. This approach aims for the highest single-session stone-free rate.

4. Temporary stent

   A JJ stent is usually left between kidney and bladder for 7-14 days while the ureter recovers.

What to expect after surgery

• Most patients go home the same day or after one night.
• A pink tinge in the urine is normal for a few days.
• Stent symptoms - frequency, urgency, flank discomfort on voiding - are common for 1-2 weeks while the stent is in place.
• Return to desk work within a few days; strenuous exercise after the stent is removed.
• Follow-up CT or ultrasound at 4-12 weeks to confirm complete clearance.

Risks

• Urinary tract infection (~2-5%).
• Small risk of ureteric injury, ureteric perforation or false passage.
• Residual fragments requiring a second procedure.
• Rare risk of ureteral stricture (scarring), which appears higher with certain manufacturer-preset high-power laser settings on newer platforms.⁵
• Post-operative pain related to the temporary stent.

Patient information brochures

Ureteroscopy for stone(s) PDF - BAUS patient brochure Advice to patients with a ureteric stent PDF - BAUS patient brochure Diagnostic ureteroscopy PDF - BAUS patient brochure

Related pages

References

1. Kim HJ, Ghani KR. Which is the best laser for lithotripsy? Holmium laser. European Urology Open Science. 2022;44:27-29.
2. Singh D. High-powered laser platforms expand ureteroscopic options for complex patients. Urology Times. 2026.
3. Mahmood SN, et al. Efficacy of flexible ureterorenoscopy in treating multiple renal stones. Archivio Italiano di Urologia e Andrologia. 2024;96(3):12617.
4. Kim HJ, et al. (MUSIC ROCKS). Real-world stone-free rates after ureteroscopy. European Urology Focus. 2023;9(6):773-780.
5. Villani M, et al. High-power laser settings and ureteral stricture risk. World Journal of Urology. 2025.