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Now let's talk about the

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imaging of a normal pregnancy.

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Again, ultrasound is the first-line

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imaging modality in the first trimester.

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When we're looking at ultrasound images

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of a first-trimester pregnancy, it's

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important to locate an intrauterine

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gestational sac and further characterize it.

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We'll be taking a look at the mean sac

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diameter, which is an estimation of the

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gestational age of the pregnancy. We'll be

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evaluating the shape of the gestational sac

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and also its location within the uterus.

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We'll be attempting to identify a fetal pole.

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If one is identified, we'll measure it,

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obtaining a crown-rump length, which will again

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be an estimate of gestational age, and we'll

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look for the presence of cardiac activity.

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We'll look for a yolk sac, as well as any

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complications in the first trimester, including

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subchorionic hematoma or an open cervix.

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In the second and third trimesters, ultrasound

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is still the first-line imaging modality

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for evaluation of the pregnancy proper.

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However, we can use CT and MRI as needed.

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In the second and third trimesters, it's

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important to estimate the gestational

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age of the fetus, and we'll do this using

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specific fetal measurements, including

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abdominal circumference and femur length.

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We'll also document cardiac activity.

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And provide a subjective amniotic fluid

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volume unless we're reporting specific

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measurements like an amniotic fluid index.

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If you can see the placenta when you're doing

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ultrasound of a second-trimester pregnancy,

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it's important to note its location.

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Is it fundal?

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Is it low-lying?

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Is it anterior or posterior?

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In the second and third trimesters, we

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also want to document that the cervix

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is closed and identify any concomitant

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pathology that we may see on the images.