Direct In-Scope Suction Versus Standard Flexible Ureterorenoscopy

Retrograde intrarenal surgery (RIRS) is used to treat renal and proximal ureteral stones. During flexible ureterorenoscopy, stone fragments and irrigation fluid may impair visualization, and elevated intrarenal pressure may contribute to postoperative infectious complications. Direct in-scope suction (DISS) permits aspiration through the ureterorenoscope during irrigation and lithotripsy. This study will compare procedural and postoperative outcomes with and without DISS.

This single-center, prospective, randomized, parallel-group study will enroll 70 adults undergoing RIRS at Erol Olçok Training and Research Hospital. Participants will be assigned in a 1:1 ratio to standard flexible ureterorenoscopy or DISS-equipped flexible ureterorenoscopy using a computer-generated randomization sequence. Each group will include 35 participants. Clinical data will be collected during surgery and postoperative follow-up.

The standard group will undergo surgery using a 7.5 Fr Storz Flex-X2 flexible ureterorenoscope. The DISS group will undergo surgery using a 7.5 Fr single-use Claritron flexible ureterorenoscope with direct in-scope suction. Both groups will use a 9.5/11.5 Fr ureteral access sheath, guidewire, Holmium:YAG laser lithotripsy, and normal saline irrigation. Procedures will be performed under general anesthesia in the lithotomy position, with the irrigation bag positioned approximately 100 cm above the patient.

Eligible patients will be aged 18 years or older and undergo RIRS by the same surgical team for a single renal or proximal ureteral stone. Patients with multiple stones, pregnancy, preoperative urinary tract infection, or bleeding diathesis will be excluded.

Demographic and stone characteristics, operative time, fluoroscopy time, total laser energy, length of hospital stay, and need for reoperation will be recorded. Laboratory results, including white blood cell count, C-reactive protein, and creatinine, as well as urine and blood culture results when obtained, will be collected during follow-up.

The primary outcomes are postoperative fever, systemic inflammatory response syndrome (SIRS), and sepsis. Fever is defined as a body temperature >38°C within 48 hours after surgery. SIRS is defined as the presence of at least two of the following: temperature >38°C or <36°C, heart rate >90 beats/min, respiratory rate >20 breaths/min, or white blood cell count >12,000/mm³ or <4,000/mm³. For this protocol, sepsis is defined as SIRS with suspected or confirmed infection. For patients who develop infectious complications, treatment, intravenous antibiotic use, and intensive care requirements will be recorded.

Secondary outcomes include stone-free status on non-contrast computed tomography approximately four weeks after surgery, postoperative changes in white blood cell count and creatinine, and postoperative culture findings. Residual fragments ≤4 mm will be classified as clinically insignificant for the study's stone-free assessment.

The two groups will be compared using tests appropriate for the distribution and type of each variable. Categorical data will be reported as counts and percentages. A p value <0.05 will be considered statistically significant.