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Thread: Fetal Doppler Rental?
May 13th, 2013 07:15 PM #45
A lot of the 'arguments' about fetal imaging / doppler suffer from reverse causation, or just plain misinformation (like the shock wave-force needed to physically displace anything on the molecular level within the baby). The sad, sad 'argument' I have seen most oftenly cited goes something like this:
"Did you know babies subject to repeated ultrasounds during pregnancy are 10 times more likely to be born with serious birth defects!"
Sounds ominous. However, the reason these babies are getting weekly ultrasounds to monitor their growth, amniotic fluid levels, heart function, neural tube defects, renal agenesis, etc etc etc is *because* they have been diagnosed with a problem antenatally, and/or the mother had ongoing health concerns necessitating frequent monitoring of the baby. They have it totally backwards-- the ultrasound/heartbeat measurement is not the cause of their birth defects, but the birth defects cause them to get multiple ultrasounds.
Emma, I have my suspicions about why that particular group of women would be uninterested in buying a $50,000 machine, paying several thousand dollars to be trained in its use and attending a year of classes to be certified therein, and admitting that there can be pregnancy complications and/or congenital anomalies, placental problems, etc that would necessitate its use-- runs a bit counter to the "trust birth" "you don't need no fancy money-grubbing doctors" philosophy.
In answer to your specific question, fetoscopes are extremely poor substitutes for a doppler. They are basically stethoscopes and if the baby is positioned remotely suboptimally, you won't hear a blessed thing. Even if you do, it's extremely difficult to mentally calculate heartrate variability and reactivity when you're just counting along.
And unfortunately your lay midwife friends are demonstrating their complete ignorance of the physics of electricity and magnetism (which is required for entry into medical school). A doppler is an ultrasound, but in handheld mode instead of producing a visual display it produces an aural one. It calculates based on the Doppler effect, or the Doppler shift, which is the change in the apparent frequency of a wave (an ultrasonic sound wave) as the target moves towards or away from the observer (the observer being the device itself). It is used widely to measure all sorts of vascular phenomena (I use them nearly daily to check out various blood vessels), since the heart will propel blood quickly towards the observer and then away as that blood flows on down the vessel.
Doppler can have visual display as well-- again, I use cheapo ones which just make a sound as well as fancy ones that show me the color waveform of blood mixing in an aneurysm, or the upstroke and downstroke as blood flows through a semi-clogged artery, etc. Many applications. In obstetrics when you have your Level 1 sonogram (the anatomy scan) the tech uses visual doppler to image the four chambers of the heart and make sure the blood is flowing in the proper circuit.
Again there is ZERO-- I repeat not a shred-- of evidence that ultrasonic waves "disturb," "move," "disequilibrate," any synonym you like anything on the molecular level in any tissue through which they pass, including that of a developing baby. This is simply grossly unfounded scaremongering.
However, giving up on heartbeat checks and routine, detailed ultrasounds in pregnancy out of worry can have very serious consequences indeed. There are a great many fetal anomalies that, if diagnosed antenatally, can be successfully managed antenatally and/or corrected immediately after birth, assuming everyone is prepared. The importance of assessing placental sufficiency in late pregnancy cannot be overestimated, either, and that's done with a simple heartbeat check.Blade, MD
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