Retrograde intrarenal surgery (RIRS) is a widely used treatment for kidney stones; however, postoperative infectious complications remain a significant concern. This prospective randomized factorial trial aims to evaluate whether gentamicin-containing irrigation fluid and the use of a suction ureteral access sheath can reduce postoperative fever, systemic inflammatory response syndrome (SIRS), and sepsis after RIRS. The study will also investigate the independent and combined effects of these two interventions on infectious outcomes.

Subject:

The present study aims to investigate the effects of gentamicin-containing irrigation and the use of a suction ureteral access sheath during retrograde intrarenal surgery (RIRS) on postoperative infectious complications.

Objective:

The aim of this study is to evaluate the independent and combined effects of gentamicin irrigation and a suction ureteral access sheath on postoperative infectious complications following RIRS.

Retrograde intrarenal surgery (RIRS) is a commonly used minimally invasive treatment modality for renal stones, particularly for stones up to 20 mm. Although RIRS is generally considered safe and effective, postoperative infectious complications remain an important clinical concern. Fever, urinary tract infection, systemic inflammatory response syndrome (SIRS), and sepsis may occur even in patients with negative preoperative urine cultures and appropriate perioperative antibiotic prophylaxis.

A potential mechanism for infectious complications after RIRS is increased intrarenal pressure during endoscopic lithotripsy. Elevated intrarenal pressure may promote pyelovenous and pyelolymphatic backflow, allowing bacteria, endotoxins, and inflammatory mediators from the collecting system or stone surface to enter the systemic circulation. Therefore, strategies that reduce bacterial contamination within the renal collecting system and improve intrarenal drainage may help decrease postoperative infectious morbidity.

This study is designed to evaluate two intraoperative strategies intended to reduce infectious complications during RIRS. The first strategy is local antibiotic irrigation using gentamicin-containing saline solution. Gentamicin will be added to the irrigation fluid as a local intraoperative measure rather than as a systemic treatment. This approach is intended to reduce bacterial contamination within the collecting system during lithotripsy. All patients will also receive standard systemic antibiotic prophylaxis according to routine clinical practice.

The second strategy is the use of a suction-enabled ureteral access sheath. This device is intended to improve fluid evacuation, reduce intrarenal pressure, and facilitate the removal of stone dust, debris, and potentially contaminated fluid during the procedure. By improving drainage from the collecting system, suction-assisted RIRS may theoretically reduce pyelovenous backflow and the risk of postoperative systemic inflammatory or infectious events.

The study uses a 2×2 factorial design, which allows simultaneous evaluation of the independent effects of gentamicin irrigation and suction-enabled ureteral access sheath use, as well as their combined effect. This design is useful because both interventions target different mechanisms that may contribute to infectious complications: local bacterial contamination and elevated intrarenal pressure. The factorial structure will also allow assessment of whether the combination of these two approaches provides an additive or synergistic benefit compared with either intervention alone.

All procedures will be performed under general anesthesia in the lithotomy position using standard endourological techniques. Irrigation will be performed with normal saline under low-pressure conditions. In the gentamicin irrigation groups, 80 mg gentamicin will be added to each 3 L bag of normal saline. In the suction groups, a suction-enabled ureteral access sheath will be used during flexible ureteroscopy. Stone fragmentation will be performed with a holmium:YAG laser using a dusting technique, and a double-J ureteral stent will be placed at the end of the procedure according to the study protocol.

This trial may provide clinically relevant evidence regarding infection-prevention strategies in RIRS. If gentamicin irrigation, suction-assisted access sheath use, or their combination is shown to reduce postoperative infectious complications without compromising surgical success, these approaches may contribute to safer perioperative management in endourological stone surgery.

Inclusion Criteria:

• Patients scheduled for retrograde intrarenal surgery (RIRS) due to kidney stones
• Male and female patients aged 18 years or older
• Patients who voluntarily sign the informed consent form
• Patients with sterile urine culture or whose preoperative infection has been treated and urine culture has become sterile

Exclusion Criteria:

• Patients with active urinary tract infection before surgery
• Patients with chronic kidney disease
• Pregnant patients
• Patients with allergy to aminoglycoside-group drugs used in the study protocol, specifically gentamicin
• Cases in which the ureter cannot be accessed and the procedure is postponed by placing a double-J stent instead of performing dilation