SPIRAL STENT VERSUS STANDARD STENT IN PATIENTS WITH MIDSIZE RENAL STONES TREATED WITH EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY: WHICH STENT WORKS BETTER? A PROSPECTIVE RANDOMIZED TRIAL

ABSTRACT 

Purpose:

It has been proposed that stone fragment clearance with a new spiral Double-J stent (Medical Engineering Corp., New York, New York) is faster than with a standard Double-J stent. Therefore, we evaluated stent insertion, peri-interventional complications, as well as stone clearance in patients with midsize kidney stones treated with extracorporeal shock wave lithotripsy (3,500 shock waves) in a prospective randomized trial.

Materials and Methods:

A total of 32 patients were randomized for preoperative insertion of a spiral stent (16) or a standard stent (16). Stone volume was measured from an abdominal plain film. Stent inserting time and stent handling problems, as well as perioperative and postoperative complications were evaluated. Clearance of stone fragments was analyzed by abdominal plain films and ultrasound on day 1, and at the end of weeks 1, 2 and 6 after treatment or until stone fragments were completely cleared.

Results:

Median stone volume was 1.8 ccm (range 0.4 to 5.2) in the spiral stent group and 1.3 ccm (range 0.4 to 2.6) in the standard stent group (p = 0.08). Median stent inserting time was 21 minutes (range 10 to 60) in the spiral stent and 18 minutes (range 5 to 45) in the standard stent group (p = 0.94). Inserting difficulties occurred in 6 of 16 (38%) patients with spiral stents and in none with standard stents (p = 0.005). Spontaneous stent displacement occurred in 4 of 16 patients in the spiral stent group and did not occur in the standard stent group (p = 0.03). The percentage of stone-free patients 1 day, and 1, 2 and 6 weeks after treatment was 0%, 13%, 44% and 81% in the spiral stent group and 6%, 19%, 50% and 88% (p = 0.64) in the standard stent group, respectively.

Conclusions:

Spiral stents are more difficult to insert, spontaneously dislocate more often and have no advantage in overall stone clearance compared with standard stents.

Key Words:  kidney calculi , lithotripsy , stents