Retrograde Intrarenal Surgery (RIRS)

Introduction

Retrograde intrarenal surgery (RIRS) utilises flexible Ureterorenoscope (URS) and Holmium laser for small stones in difficult access areas in the kidney. The patient receives no incision. It is also an effective treatment option when treatment options, like extracorporeal shockwave lithotripsy (ESWL) have failed or there is a post percutaneousnephrolithotomy (PCNL) residual. It is also be used as first-line treatment in selected patients.

 

Contemporary RIRS for Renal Stones

Instruments

Standard instruments for RIRS include:
Flexible ureterorenoscope(URS) ( which is a flexible long tube like instrument which can approach most of the angles & corners of the kidney), Holmium laser, Video camera, Fluoroscopic support, Accessory instruments, Guide-wires, Dilators, Access sheath, Basket, Ureteric catheters

Flexible Ureterorenoscope

Standard fibreoptic flexible ureterorenoscopes have a tip size in the range of 6.75 – 9Fr. They have working channels ofFr 3.6 – 4 and standard instruments (e.g. baskets) are Fr 2.2 – 3 in size.

Holmium: YAG Laser

The Holmium: YAG laser is the lithotripter of choice for RIRS. The laser energy is delivered via fibres to the stone surface, where it is absorbed and turned into heat energy that pulverises the stone into dust by a “photo thermal” effect. Thus,Stone fragment retrieval with basket / grasping forceps may not be necessary. Laser lithotripsy can be carried out safely in patients on anticoagulants albeit with a higher risk than normal patient.

Video Camera and Fluoroscopy

Accurate and clear visualisation of the ureter and pelvicalyceal system using video camera is possible due to revolution in optics. Complimentary usage of X – ray fluoroscopy & contrast medium help achieve good success rates for stone clearance.

Ureteric Catheters
6 Fr double-J ureteric catheters will be used for pre-stenting or temporary stenting post-op. Pre-stenting with double-J ureteric catheter for about 1- 2 weeks for ureteric dilatation would be required to facilitate the technical ease & safety of the procedure. However some patients may directly undergoRIRS without Ureteric stenting preoperatively on a case to case basis.

Indications

• Failed extracorporeal shockwave lithotripsy
• Radiolucent stones
• Concomitant ureteric and renal stones
• Anatomical problems e.g. infundibular stenosis
• Bleeding disorders
• Need for complete stone removal e.g. pilot

 

Pre-operative Assessment and Followup

Imaging assessments on stone load, stone location and pelvicalyceal anatomy are essential before the procedure. CECT urogram is the most commonly used imaging modality. Pre-operative retrograde pyelogram would be required for patients with impaired renal function. Patient needs to give an informed consent regarding the RIRSprocedure and potential complications, whereby possibilities of requiring postoperative stenting, second-look procedure, auxiliary procedure and failed procedure are all thoroughly explained and understood. Urine cultures are performed to ensure that patients have sterile urine before the procedure. Patients with asymptomatic persistentbacteriuria should be given an appropriate antibiotic for prophylaxis. Patients are put under general anaesthesia with prophylactic antibiotics administered on-induction. Patients will usually have their first follow-up visit scheduled about 1-2 weeks post-op. Treatment outcome will be assessed with a KUB radio-graph or additional imaging (NCCT KUB/ CECT Urogram) as indicated, 6 – 8 weeks after the procedure.

 

Guidelines

ESWL and PCNL are the recommended primary treatment options for renal stones (stone sizlte 20mm and 20mm or more respectively) in the EAU Guidelines. FlexibleURS was stated as an effective treatment for ESWL refractory renal calculi (Grade A recommendation), with reported stone free rates of 50 – 80% for calculi <1.5cm in size, while larger stones can also be treated successfully. Post-operative ureteric stenting is optional and routine ureteric stenting after uncomplicated ureteroscopy is not necessary. Indications for post- operative ureteric stenting include ureteric injury, ureteric stricture, solitary kidney, renal insufficiency, large residual stone burden & inflammation & oedema at impacted stone site.

 

Post-operative Management and Follow-up

RIRS can be a daycare procedure in selected patients, e.g. – patients with stable creatinine / no co morbidity, smaller stone burden as well as uncomplicated procedure. Considering suboptimal results of ESWL for lower pole stones, flexible URS could become a reliable first-line treatment for lower pole stones < 1.5 cm.” Flexible URS is also an option when ESWL might be contraindicated or ill-advised (Grade C recommendation) e.g. patients on anticoagulants5, obesity, pregnancy etc. Patients must understand RIRS involves stenting prior to the procedure usually.

 

Complications Of Ureteroscopy

A meta-analysis published by the EAU-AUA Guidelines panel has evaluated the most relevant complications of ureteroscopy – sepsis, steinstrasse, stricture, uretericinjury and urinary tract infection. The overall complication rates reported in recent literature are 5 – 9%, with a 1% rate of significant complications. Serious complications, including renal loss and death, were rare.

 

Conclusion

RIRS for renal stones is an effective treatment option for ESWL refractory renal calculi; it is also useful in situations like patients with bleeding tendency or pregnancy.

 

Information for patient understanding

RIRS usually is a two stage procedure, i.e. stenting followed by RIRS after 7-10 days. A small number of cases may need a repeat stenting at the time of RIRS depending upon operative findings, but this stent would be removed1-2weeks later as daycare under local anaesthesia.