RIRS: Retrograde Intra Renal Surgery for kidney stones treatment

1. Introduction

Definition and Purpose of the RIRS

RIRS (Retrograde Intrarenal Surgery), or endoscopic retrograde renal lithotripsy, is a minimally invasive surgical technique that treats kidney and ureteral stones using a flexible instrument inserted via the urethral route. This allows access to the kidney through the urinary tract without skin incisions.

History and Evolution of Technology

Endoscopic surgery has evolved rapidly thanks to the development of flexible and miniaturized instruments and the introduction of the holmium laser, which has made it possible to fragment even stones of significant size. RIRS has gained popularity over the past two decades as an alternative to extracorporeal lithotripsy (ESWL) and percutaneous surgery (PCNL).

Indications and Contraindications

Main indications:

• Kidney stones less than 2 cm.
• Stones in patients with anatomical abnormalities or coexisting diseases that preclude other techniques.
• Upper ureteral stones that cannot be treated with other methods.
• Failure of ESWL or PCNL.

Contraindications:

• Untreated urinary infections.
• Severe ureteral obstructions or ureteral strictures.
• Coagulopation non corrette.
• Pregnancy.

2. Anatomy of the Urinary System

Description of renal anatomy and urinary tract

The kidney produces urine, drains through the calyceal system into the renal pelvis and ureter, to the bladder, and finally is eliminated through the urethra. Stones can form anywhere in this system, most commonly in the kidneys.

Localization and Formation of Kidney Stones

Kidney stones are mineral deposits that form when substances in the urine (such as calcium, oxalate, or uric acid) concentrate and crystallize. They can obstruct the normal flow of urine, causing pain, infection, or kidney damage.

3. Preoperative Preparation

Clinical Evaluation and Medical History

Before proceeding with the surgery, a complete clinical evaluation is essential that includes:

• Physical examination and assessment of symptoms.
• Detailed clinical history to identify any risk factors or comorbidities.
• Analysis of the drugs taken by the patient, with particular attention to anticoagulants.

Diagnostic tests

Imaging examinations, such as non-contrast abdominal CT or renal ultrasound, are essential for the precise location of stones and surgery planning. Blood and urine tests help assess your overall health and whether you have infections.

Management of Pre-Existing Urinary Infections

If a urinary tract infection is present, it must be treated with antibiotics before proceeding with the surgery. Infections increase the risk of complications.

Antibiotic prophylaxis

Antibiotics should be used prior to the procedure to prevent post-operative infections, particularly in patients at increased risk.

Psychological Preparation and Informed Consents

It is important to inform the patient about the procedure's risks, benefits, and possible complications. Informed consent must be signed.

4. Equipment Used

Flexible Endoscopes

Flexible ureteroscopes provide easy access to hard-to-reach areas, such as lower kidney calyxes, improving treatment effectiveness.

Display Systems

High-definition camera systems are used for a clear view during surgery.

Laser to Olmium

It is the most common tool for fragmenting calculations. The holmium laser can be adjusted to fragment or pulverize stones as needed.

Tools Accessories

Forceps, fragment collection baskets, and ureteral stents to maintain the patency of the ureter.

5. Surgical technique

Access to the Urinary Tract: after anesthesia, the urinary tract is accessed through the urethra, and the ureter is located using a cystoscope. A ureteral sheath is placed to facilitate the passage of instruments.

Navigation through the Ureter to the Kidney: the ureteroscope is gently advanced through the ureter to reach the kidney

Identification and Localization of Computing: Once it reaches the renal cavity, the stone is visually located and prepared for lithotripsy.

Fragmentation with the Holmium Laser: The laser pulverizes or fragments the stone into smaller pieces that can be removed or expelled with urine.

Extraction of Residual Fragments: The larger fragments are removed using a basket, while the smaller ones can be left to be expelled naturally.

Ureteral Stent Placement: A ureteral stent is often placed at the end of surgery to facilitate urinary drainage and prevent obstructions.

6. Immediate post-operative

Pain Monitoring and Management: Pain is generally controllable with analgesics. Close monitoring of the general condition is essential to recognize any complications.

Post-operative examinations: Imaging and laboratory tests are performed to confirm the success of the surgery and monitor the absence of complications.

Management of the Ureteral Stent: The stent is usually removed after a few days or weeks. During this time, the patient may experience kidney discomfort or spasms.

7. Complications and Their Management

Although rare, complications may include infections, persistent hematuria, or ureteral injury. Treatment is individualized based on the nature of the complication and may include medication or, in rare cases, additional interventions.

8. Results and Success of the Procedure

The success of RIRS is high, with a stone elimination rate of more than 80-90%, especially for stones less than 2 cm in size. The procedure offers faster recovery and fewer complications than more invasive techniques.

9. Follow-up and Long-Term Management

After stent removal, periodic follow-ups are performed to verify the absence of recurrences. It is advisable to take preventive measures to avoid the formation of new stones, such as dietary changes and using specific medications.

10. Comparison with other Treatment Techniques

RIRS offers several advantages over ESWL and PCNL regarding invasiveness and recovery, but there may be better choices for extensive calculations (greater than 2 cm), where other techniques may be preferable.

Conclusion

Endoscopic retrograde renal lithotripsy (RIRS) is a safe and effective solution for treating small and medium-sized kidney stones. It is minimally invasive and offers a high success rate with reduced recovery time.