This study investigated a previously unassessed operating position for ureteroscopic holmium laser lithotripsy in patients with upper ureteral stone. The reverse Trendelenburg position can reduce migration and improve the stone free rate (SFR). Moreover, less utilization of flexible ureteroscope and hospital stay in reverse Trendelenburg position can reduce the medical cost. Therefore, it can be safely used as an optional surgical method for the treatment of upper ureteral stones.

With the rapid development of urological endoscopy technology, minimally invasive surgery has replaced open surgery in ureteral stones. The majority of upper ureteral stones are treated with endoscopic techniques. In the last 10 years, URSL (Ureteroscopic Lithotripsy) has surpassed SWL (Shock-wave lithotripsy) with its wide use [1]. While URSL was considered in the foreground according to SWL for proximal ureteral stones larger than 1 cm, today it is recommended with equal efficiency and safety with SWL for stones smaller than 1 cm [2]. However, migration of stones to renal calyces is a common problem during ureteroscopic treatment of upper ureteral stones. Migration can be caused by many factors such as the momentum of the laser pulse, stone manipulation of the laser fiber, fluid irrigation pressure and the increase of ureteral dilatation. The degree of migration varies according to the impaction level of the stone and the location in the ureter [3].

The migration of the stone to the renal pelvis and calyces increases the operation time and cost [4-6]. Recently published American Urological Association Guidelines reported that ureteroscopy of ureteral stones performed an average of 1.33 procedures per patient [7]. In order to prevent stone migration, tools have been developed that are used in the proximal of the stone or that interfere with the stone in the kidney after retreatment. Although these developed devices are effective, it has been determined that their additional use causes an additional cost of $ 278 per case as well as extending the operation time [8]. In addition, placing an anti-migration device in the ureter can restrict laser fiber manipulation. Ureterorenoscopes (Flexible URS) that can flex 270 degrees, which can be used to intervene in the stone after retraction into the kidney, have made a very serious improvement, but these devices are not yet available in all centers, especially in developing countries.

There is an in-vitro study using polymer tubes that predict that the proximal ureter should stay higher than the distal ureter in order to prevent retrograde in proximal ureteral stones [9].

Inclusion Criteria:

• Obstructive upper ureteral stones

Exclusion Criteria:

• Presence of stent in the ureter at the beginning of the operation
• Serum creatinine value> 1.5 mg / dL
• Pathological ureteral strictures
• Previous open surgery history for the ureteral stone
• Previous pelvic radiotherapy history
• Pregnancy
• Solitary kidney