A test for cavitation as a mechanism for intestinal hemorrhage in mice exposed to a piezoelectric lithotripter.

This study tested the hypothesis that intestinal hemorrhage produced by exposure to lithotripter fields depends upon the presence of gas in the intestine. The extent of hemorrhage in the gas-containing intestines of pregnant mice was compared to the amount of hemorrhage in the bubble-free intestines of their fetuses. On day 18 of gestation, the abdominal regions of pregnant C3H mice (n = 6) were exposed to 200 pulses from a piezoelectric lithotripter. Acoustic pulses had a peak pressure amplitude of 10 MPa and were administered at a rate of approximately 1 Hz. All maternal intestines showed hemorrhagic regions extending several centimeters in length. In contrast, only 1 of 43 exposed fetuses showed an intestinal hemorrhage and this one lesion was less than 1 mm in diameter. These results support the hypothesis of the study and are consistent with a cavitation-related mechanism for the production of intestinal hemorrhage by exposure to acoustic fields.