Sounding out gallstones.

Sounding out gallstones 

If shock waves can be used to bust up kidney stones, why not gallstones? The Food and Drug Administration has approved the use of a shock-wave generator for kidney stones (SN: 1/12/85, p. 24); now a West German group has successfully used the machine, called a lithotripter, on patients with gallstones.

In the procedure, the patient sits in a water-filled stainless steel tub. An underwater spark-gap electrode is fired, releasing a shock wave that is aimed by a reflector toward the gallbladder. As many as 1,500 shocks are given, each lasting a microsecond, and stone-disintegrating drugs are used to dissolve the fragments that remain.

University of Munich researchers led by Tilman Sauerbruch used the technique on 14 patients with stones in the gallbladder or bile duct. In six of nine patients with stones in the gallbladder, the fragments disappeared completely within 25 weeks. And bile duct stones in four of five patients were broken up and spontaneously passed or removed by a tube threaded into the duct, the researchers report in the March 27 NEW ENGLAND JOURNAL OF MEDICINE. The only adverse effects seen were transient pain in two people and mild inflammation of the pancreas of one person.

But the technique has definite limitations, they note. Fragments still remained in some of the patients. The study involved only patients in good health, with but a few small stones that could be easily visualized with X-rays or ultrasound. By these criteria, they note, only 5 to 10 percent of people with gallstones are good candidates. Their cautionary note is echoed in an accompanying editorial by Albert G. Mulley Jr. of Harvard Medical School, who states that randomized trials comparing lithotripsy with other techniques are needed.

The procedure may prove worthwhile in combination with direct infusion of a stone solvent, says Johnson Thistle of the Mayo Clinic in Rochester, Minn. Thistle's group has worked out a way to dissolve gallstones by feeding methyl tert-butyl ether into the gallbladder (SN: 2/16/85, p. 104), which has continued to be successful in clinical trials, he told SCIENCE NEWS. They are looking into the lithotripter procedure to see if it can be used in combination with the solvent. "There may be selected patients for whom breaking up the stones beforehand will make them dissolve more quickly," he says.