Reassessing the efficacy of the Dornier MFL-5000 lithotriptor

The Dornier MFL-5000* is a multifunctional lithotriptor unit that has been purported to be highly efficacious for treating stones. Our experience led us to believe that the actual success rates are not as high as those reported by others. We objectively reexamined the efficacy of this device and factors contributing to treatment success or failure.

We retrospectively reviewed the records and x-rays of 105 consecutive patients treated with extracorporeal shock wave lithotripsy (ESWL*) using the MFL-5000 during an 18-month period from September 1997 to March 1999. One patient was excluded from study due to a stone within a caliceal diverticulum. Patients were divided evenly by gender and stone laterality. In 70% of cases a stent was placed preoperatively to relieve obstruction and/or facilitate the passage of calculous fragments. The majority of stones (70%) were 10 mm. or less. Treatment success was determined by examining x-rays done preoperatively and at a median of 4 weeks postoperatively.

ESWL was successful in only 47% of our patients, defined as residual stone fragments 2 mm. or less. A secondary procedure was required in 27% of the patients, including repeat ESWL in 6, ureteroscopic stone manipulation in 14, percutaneous tube placement in 1 and percutaneous nephrolithotripsy in 7. Factors contributing to secondary procedures and poor stone clearance were a stone burden of greater than 100 mm.2 and mid pole location (p = 0.0242 and 0.016, respectively). Poor stone fragmentation and clearance were noted despite significantly more shocks delivered (p = 0.0122). Only a small stone burden of 50 mm.2 or less responded well to ESWL (p = 0. 0142).

These results compel us to reconsider the effectiveness of the Dornier MFL-5000 lithotriptor. We encourage groups at other institutions to reexamine and report their success rates. We recommend the use of this lithotriptor only for a stone burden of 50 mm.2 or less.