The video starts with a technician holding an ultrasound probe
on the belly of a reclining pregnant woman.
Both are watching an image moving on a monitor next to
the mother as the technician moves the probe.
Ultrasound is one of the most useful procedures for
monitoring a baby's prenatal development.
With ultrasound,
doctors can check for defects of the head, spine, chest, and limbs;
diagnose serious conditions like placenta previa or breech birth;
and check to see whether the mother will have twins or triplets.
A box calls out the image of the belly and technician's
hand holding the probe to the left side of the screen.
Captions around the image repeat what the narrator says.
Ultrasound can be used anytime during pregnancy from the fifth week until delivery.
It uses inaudible sound waves to "see" the baby inside the uterus.
These sound waves bounce off solid structures in the body
and are transformed into an image on a screen.
Here's how ultrasound works.
On the left of the screen is a tennis ball.
On the right is an ultrasound screen.
A square of glass overlays the ball.
Pretend this tennis ball is an organ in the body.
This piece of glass represents the ultrasound image.
Like this piece of glass,
an ultrasound image is actually flat and two-dimensional.
If we could pass this tennis ball through the glass,
the ultrasound image would show wherever the two are in contact.
Let's watch the same thing on an ultrasound.
As the ball seems to rise through the glass,
a white ring shows on the screen.
The white ring is the reflected image of the outer part of the tennis ball.
The ball is cut in half to show its inside behind the glass.
A "Solid Area" caption indicates the outline of
the ball and the white ring on the screen.
Like many organs in the body,
the tennis ball is solid on the outside, and hollow on the inside.
Solid structures, like bones and muscles,
reflect sound waves that show up as light gray or white images.
Soft or hollow areas like the chambers of the heart don't reflect sound waves.
So they show up as dark or black areas.
An ultrasound monitor fills the screen.
While not clearly distinct,
the images outline the general form of a fetus.
The head appears to be in the upper left section of the monitor.
In an actual ultrasound of a baby in the uterus,
the solid structures in the baby’s body are transmitted back to
the monitor as white or gray images.
As the baby moves back and forth,
the monitor shows the outline of his head.
The eyes show as dark spots in the head.
The region of the brain and the heart are also shown.
Remember, ultrasound only shows a flat image of the baby.
A superimposed illustration of the fetus shows
how the fetus actually looks in the uterus.
An illustration of a fetus is overlain on the monitor screen.
The illustration is removed, leaving just the ultrasound image.
Ultrasound is still one of the best methods for physicians
to visually diagnose major physical defects in the growing baby.
Even though there are no known risks for ultrasound at present,
it is highly recommended that pregnant women consult
their physician before undergoing this procedure.