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Re: no subject received Wed, 16 Oct 2002 14:56:28 -0500From: James S. Smeltzer (gaperina@mindspring.com)Tue Oct 22 20:54:45 2002
Philippe, My personal opinion is that the issue is heat. The MI does not aggregate total heat transfer to the patient or any object presumed to be an embryo. Here opinion ends. The heat flux to and out of an embryo depends on the conditions, the energy delivered, the energy absorbed and the tissue perfusion. It depends on time only to the extent that an equilibrium flux rate is not achieved at a temperature safe for the embryo. If you insonate a larger field, which happens to be an entire embryo, at MI power levels proven safe for a sub sample of the field (2-D sonography), you do not necessarily provide safe (Nonteratogenic) power (equilibrium temperature) to the embryo. I stand absolutely on the fact that there is a pioneer (or from the embryo's point of view - guinea pig) risk as long as actual monitored and measured experience with an actual drug or modality in human embryos does not preclude any measurable increase in problems - theoretical considerations and animal experiments aside. I stand absolutely on the fact that thalidomide was proven safe in two species before given to women who were pregnant (not legally in the US, thanks to the FDA which prefers to let Asian and European fetuses be used as post-marketing guinea pigs). I stand absolutely on the fact that heat is a proven teratogenesis in humans. I will state categorically that women who subject their embryos to "cute" 3-D shows are subjecting them to unknown risks. I will state categorically that early 3-D embryonic sonography necessarily exposes the early embryo to more sound energy than is necessary to document a heart beat and crown-rump length, and are, therefore, inherently violating the ALARA principle. Besides these facts, the rest is conjecture. Jim
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> [From: Philippe Jeanty. MD, PhD; -- --------------------------------------- > [To: Multiple recipients of list ULTRASOUND; > [Date: Tuesday, October 22, 2002 01:55:14 PM >Hey Jim.... >Are these comment documented evidences or personal opinions ? >Do folks who use 3D expose the fetus longer then folks who do not ? what is >the average time of exposure in your environment ? What typical values of MI >and TI do you have on your images ? > >I would think that the issue is way more complex then your note let it >appear, and that your note, by simplifying too much may give a distorted >view to reality. > >Would you possibly reconsider the statements you made ? > > -----Original Message----- >From: ultrasound@obgyn.net [mailto:ultrasound@obgyn.net] On Behalf Of >James S Smeltzer MD >Sent: Monday, October 21, 2002 10:19 PM >To: Multiple recipients of list ULTRASOUND >Subject: Re: no subject received Wed, 16 Oct 2002 14:56:28 -0500 > >At 02:59 PM 10/16/2002 -0500, you wrote: >>Hi my name in Fabiola savinovich and I am 29 weeks pregnant. i would like >>to know were in MIami can I get a 3D ultrasound performed. Thanks >> > >Hi Fabiola! > >Usually a 3-D ultrasound does not obtain more information about your baby >than a skilled examiner gets with a regular ultrasound. It does deliver >more total energy to the baby. We know this is heat. We also know that >heat is a known cause of birth defects in the first 3 months inside. Right >now lots of women are using their babies as guinea pigs to see if this is >enough heat to be a problem or not. Once a few million women have had this >test and had follow-up on their babies we may know that it is safe. Then >again we may know that it is risky. > >If you or the baby's father have some problems with the development of the >skeleton or certain physical deformities that might be inherited, then this >may be a better test for you despite this potential risk. Otherwise I >would talk the unknown risk and benefits over with your doctor. In general >it is usually wise to let someone else use their baby as a guinea pig and >avoid exposing your baby to unknown and new things until they are known to >be safe, unless they are the best possible medical alternative for some >other reason. > >Jim Smeltzer, MD
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