Hemorrhage near fetal rat bone: Preliminary results

Timothy A. Bigelow, Rita J. Miller, James P. Blue, William D. O'Brien

Research output: Chapter in Book/Report/Conference proceedingConference contribution


High-intensity ultrasound has shown potential in treating many ailments requiring noninvasive tissue necrosis. However, little work has been done on using ultrasound to ablate pathologies on or near the developing fetus. For example, Congenital Cystic Adenomatoid Malformation (cyst on lungs), Sacrococcygeal Teratoma (benign tumor on tail bone), and Twin-Twin Transfusion Syndrome (one twin pumps blood to other twin) are selected problems that will potentially benefit from noninvasive ultrasound treatments. Before these applications can be explored, potential ultrasound-induced bioeffects should be understood. Specifically, ultrasound-induced hemorrhage near the fetal rat skull was investigated. An f/1 spherically focused transducer (5.1-cm focal length) was used to expose the skull of 18- to 19-day-gestation exteriorized rat fetuses. The ultrasound pulse had a center frequency of 0.92 MHz and pulse duration of 9.6 μs. The fetuses were exposed to 1 of 4 exposure conditions (denoted A, B, C, and D) in addition to a sham exposure. Three of the exposures consisted of a peak compressional pressure of 10 MPa, a peak rarefactional pressure of 6.7 MPa, and pulse repetition frequencies of 100 Hz (A), 250 Hz (B), and 500 Hz (C), corresponding to time-average intensities of 1.9 W/cm 2, 4.7 W/cm2, and 9.4 W/cm2, respectively. Exposure D consisted of a peak compressional pressure of 6.7 MPa, a peak rarefactional pressure of 5.0 MPa, and a PRF of 500 Hz corresponding to a time-average intensity of 4.6 W/cm2. Hemorrhage occurrence increased slightly with increasing time-average intensity (i.e., 11% for A, 28% for B, 31% for C, and 19% for D with a 9% occurrence when the fetuses were not exposed). The low overall occurrence of hemorrhaging may be attributed to fetal motion (observed in over half of the fetuses from the backscattered echo during the exposure). The mean hemorrhage sizes were 3.1 mm2 for A, 2.5 mm 2 for B, 2.7 mm2 for C, and 5.1 mm2 for D. The larger lesions at D may be related to these fetuses moving less as only 40% of the fetuses were observed moving for this exposure condition.

Original languageEnglish (US)
Title of host publicationTHERAPEUTIC ULTRASOUND
Subtitle of host publication5th International Symposium on Therapeutic Ultrasound
Number of pages5
StatePublished - May 8 2006
EventTHERAPEUTIC ULTRASOUND: 5th International Symposium on Therapeutic Ultrasound - Boston, MA, United States
Duration: Oct 27 2005Oct 29 2005

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherTHERAPEUTIC ULTRASOUND: 5th International Symposium on Therapeutic Ultrasound
Country/TerritoryUnited States
CityBoston, MA


  • Fetal bone
  • Hemorrhage
  • Ultrasound bioeffects

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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