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Ureteroscopic manipulations instigating the tunnel technique: the treatment of impacted ureteral stones larger than 2cm

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Ureteroscopic manipulations instigating the tunnel technique: the treatment of impacted ureteral stones larger than 2cm


The goal of treating ureteral calculi is to achieve complete stone clearance with minimal patient morbidity, alleviation of pain, and safety profiles. To that end, the purpose of this study was to verify the safety and efficacy of retrograde endoscopic lithotripsy as the treatment modality for large impacted ureteral stones relying on a personal technique that we call the Tunnel Technique (TT): copying the elemental principle of excavating tunnels in mountains.

Methods and Materials:

We retrospectively evaluated endoscopic outcomes compiled from the records of 43 patients amongst which 11 were diagnosed with impacted ureteral stones to determine the salvation role of ureteroscopy.

From November 2013 to December 2014, the 11 subjects were treated following a retrograde endoscopic procedure using a small-caliber ureteroscope and a holmium laser lithotripter investigating the merits of the Tunnel Technique that sought to fragile the stabilised stone for purposes of complete and safe fragmentation. It is worth mentioning that the 11 patients did not undergo any pre-operatory stenting (Diagram 3). Although the mean maximal stone size was 3.3 cm; all patients had had at least a six-month ureteral obstruction as evidenced by the CT Scan findings.

Sample cases selected for the study:

Case 1: Male aged 54, presenting with an impacted right lumbar ureteral calculi of 33 mm of size and 1340 UH.

Case 2: Male aged 47, presenting with an impacted left ureteral lumbar calculi of 31 mm of size and 1297 UH.


-The 11 impacted calculi were treated exclusively using a retrograde ureteroscopy LASER.
-The impacted stones were fragmented thoroughly after a single endoscopic procedure.
-One month after, no patients had evidence of residual stones.

The 11 impacted ureteral stones were fragmented completely throughout a single endoscopic procedure. The mean operative time was 56 minutes. No intraoperative complications or postoperative ureteral stricture transpired. JJ sent placed to 2 patients and ureter catheter to 4 patients. A month after treatment, no patient had evidence of residual stones.

Merits of the Tunnel Technique:

During a normal URS procedure in the extraction of non impacted ureteral calculi, water flux injected increases the Intra Renal Pressure (IRP) that might make the urologist’s intervention complicated. The urologist has to reduce the intervention’s period as to avoid any complications that might hinder the renal function. By implementing the TT, the urologist will not be slowed down by the IRP constraints as the impacted calculi functions as a barrier that maintains steady the initial pressure.

The TT as a treatment procedure goes through 2 different steps:

1. Step One: Fragile the impacted stone during the TT  excavation procedure via standard laser techniques: dusting, fragmentation and popcorning.
2. Step Two: A slight perforation through the distal shell of the calculi will permit a smooth decrease of  the IRP driving  a hydraulic thrust of the fragments towards the bladder. No fragments flush.


This study has sought to demonstrate that URSL would attain satisfactory results for ureteral calculi greater than 2 cm. It is our recommendation that endoscopic lithotripsy through the Tunnel Technique be considered as an effective therapy.

In cases of obstructive ureteral stones our technique has proved to be a safe and effective means. It has the main advantage of offering both immediate relief from pain and complete stone fragmentation. The TT = Comfort & Efficacy


Extensive studies are prerequisite to corroborate and recommend sound benefits of the Tunnel Technique.


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