This study aimed to present the technique and evaluate the outcomes of mini-endoscopic combined intrarenal surgery (mECIRS) based on the initial results from a single center.

From July 2022 to December 2024, 32 patients with complex renal calculi who underwent mECIRS using the through-through approach at our department were analyzed. One patient, referred from the internal medicine department, was excluded due to complex comorbidities prior to surgery. All cases were performed in the Galdakao-modified supine Valdivia position by the same two urologists. Two 8 Fr nephrostomy tubes were indwelled, with their tips positioned in the upper ureter and anchored to the skin with sutures by a radiologist the day before surgery. During the operation, a stiff guidewire was inserted into the upper ureter through one of the pigtail catheters, and the guidewire was grasped with a stone basket inserted through the rigid nephroscope and exited via the urethral meatus. A 15 Fr channel was established for PCNL, followed by the retrograde insertion of a 10/12 Fr flexible ureteroscope sheath. The stone-free rate was defined as a residual stone size of <4 mm.

The patients' mean age was 61.0 years. The mean maximum stone diameter was 30.12 mm, and 93.8% of patients had lower pole kidney stones. A nephrostomy tube was not required after the operation in 84.4% of patients. Three patients required intensive care unit management after the operation and were later transferred smoothly to the general ward. The primary stone-free rate was 68.8%. The mean post-operative Foley catheter indwelling time was 2.1 days. The average length of hospital stay after mECIRS was 3.3 days. Five patients required a sequential operation due to significant residual calculi.

Mini-endoscopic combined intrarenal surgery using the through-through approach is a safe, effective, and efficient method for managing complex renal calculi. It stabilizes the kidney and eliminates the risk of inadvertent loss of access during the procedure, allowing for the creation of a smaller tract compared to the conventional 22/24 Fr channel. This technique may enhance patient satisfaction and shorten recovery time.