How to Read Sonograms

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Sonogram showing fetus with head on the right.
Sonogram showing fetus with head on the right. (Image: Nevit Dilmen: wikimedia.org, Drahreg01:wikimedia.org, Gray's Anatomy, Espinola-Zavaleta N, Soto ME, Castellanos LM, Játiva-Chávez S, Keirns C.: wikimedia.org, Patrick J. Lynch: wikimedia.org, edanley:Flickr.com, Jheuser:wikimedia.org)

You may see sonograms of friends and family online, or pictures of celebrities getting an ultrasound. You or someone close to you has probably had one. How are those pictures taken, and is it more than just a black-and-white blur? Sonograms, like this picture of a baby, are taken with sound waves using an ultrasound machine. Sonograms let you see the heart beating in real time, detect gallstones, measure a baby's heartbeat, and detect internal bleeding. Even if inexperienced, you can read a sonogram.

Look at the sonogram. The top of the sonogram is narrow because sound is coming from the narrow probe, which is held against the skin to take the picture, and spreading out as it goes into the body. The picture is created by sound bouncing against objects and returning to the probe. The bottom of the screen is farther away from the probe. In this picture, you can see that there is a fetus (baby) inside the uterus.

Fetus is looking up at the probe, head is on the right.
Fetus is looking up at the probe, head is on the right.

Look for the little white dot on the sonogram. This dot is always on the left side of the screen and indicates the side of the probe that has a little notch or bump on it. Holding the probe with the dot toward the head will mean that the head is toward the left and the feet are on the right; this is known as a longitudinal view. A "trans" view is taken with the notch and dot pointing either left or right.

Longitudinal view with white dot. Kidney is on the right, liver on left and diaphragm in between.
Longitudinal view with white dot. Kidney is on the right, liver on left and diaphragm in between.

Look for dark areas. Dark color is something anechoic, literally, "without echo," which transmits sound very well, like amniotic fluid, water, urine or fresh blood. This picture comparing the anatomical schematic to the ultrasound image allows you to see that the kidney sits underneath the diaphragm below the liver. The thin black stripe sitting below the liver and above the kidney is blood or free fluid around the liver. In a trauma patient, blood in the belly is serious and may be a reason to take a patient to surgery depending on where the blood is coming from.

Trauma sonogram of kidney sitting underneath diaphragm and liver viewed through ribs.
Trauma sonogram of kidney sitting underneath diaphragm and liver viewed through ribs.

Put the probe below the belly button, and look down through the bladder, which is full of urine, and it will appear dark on the inside. Fluid-filled structures like the bladder work as an "acoustic window" to let you see what's on the other side. Light colors represent things that reflect sound, like walls of the bladder in this picture. Cysts in an ovary will look dark; you can see the ovaries in this pic to the right and left of the bladder (RO for right ovary and LO for left ovary).

Full bladder with ovaries on either side at bottom of picture.
Full bladder with ovaries on either side at bottom of picture.

To take a transabdominal picture, the probe looks from the belly outside through the bladder into the uterus. The transvaginal picture is taken by putting the probe into the vagina and looking directly up into the uterus. The vagina is behind the bladder, and above the vagina is the uterus, or womb.

For the four-chamber view of the heart, line up the probe in the fourth or fifth rib space below the nipple and point it between the ribs toward the right shoulder.

Place probe between ribs to see the heart underneath.
Place probe between ribs to see the heart underneath.

The heart is filled with blood, and it will appear black on the inside, but the beating walls and moving valves will appear white because they reflect sound. When you get the heart in your sights, the ventricles (labeled L.V. and R.V. for left and right ventricle, respectively) are closest to the probe and the chest wall, and the atria (R.A. and L.A.) are the farthest away.

Four-chamber view with left ventricle (L.V.), right ventricle (R.V., left atrium (L.A.), and right atrium (R.A.)
Four-chamber view with left ventricle (L.V.), right ventricle (R.V., left atrium (L.A.), and right atrium (R.A.)

Hold the probe next to the breastbone between the ribs; it allows a better view of how well the ventricles are contracting in the parasternal view.

Parasternal view
Parasternal view

Turn the doppler function on, center the target over the beating heart and listen to the heartbeat. This is also a way to check whether the fetus is under stress.

The doppler function allows you to measure the heartbeat.
The doppler function allows you to measure the heartbeat.

To look at the valve function, the color doppler can tell you if the valves are functioning normally. In this picture of mitral regurgitation, the orange color signifies blood moving backwards out of the left ventricle into the left atrium in the four-chamber view.

Color Doppler showing mitral regugitation.
Color Doppler showing mitral regugitation.

Hold the probe in the patient's upper right side of the abdomen (see bottom left in picture), and tilt it back and forth until you see a dark circle, which is the gallbladder. The gallbladder is the dark circle in the middle of the field (Gallenblase). The edge of the gallbladder closest to the probe at the top of the screen is bright because it is reflecting sound.

Gallbladder (dark circle) and gallstone (with comet tail shadow)
Gallbladder (dark circle) and gallstone (with comet tail shadow)

Even if you don't speak German, you can see whether the gallbladder contains a gallstone, which looks like a comet (Gallenstein) with a dark shadow behind it (Schallschatten).

To get the best pictures of the gallbladder, an organ that sits under the liver, sonographers may ask the the patient to roll onto the left side so that the gallbladder moves towards the abdominal wall and comes closer to the probe.

Gallbladder (dark) with many comet tail shadows representing stones
Gallbladder (dark) with many comet tail shadows representing stones

Tips & Warnings

  • The probe is the expensive end of the machine. To keep getting great pics, don't drop it or trample on the cord. If the images look too dark or too bright, adjust the gain setting.
  • These instructions should not substitute for the advice of your health-care provider. If you are training in an accredited environment, do not use these instructions alone to make a medical decision.

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