Ultrasound During Pregnancy

Ultrasound During Pregnancy

Ultrasounds have become a regular — and very welcome — part of prenatal care. Early in pregnancy, ultrasounds are used to confirm the fetal heartbeat and a uterine (as opposed to ectopic or tubular) pregnancy. Later, ultrasounds screen for fetal growth, placenta location, and umbilical cord, as well as the baby’s general health and anatomy. Ultrasounds can also be useful for checking the length of your cervix if there is any suspicion that you may be in preterm labor.

Who an ultrasound during pregnancy is for

All pregnant women should receive more than one ultrasound during pregnancy.

When an ultrasound during pregnancy is done

Usually, a woman gets a minimum of two sonograms during her pregnancy, one in the first trimester and one in the second trimester.

First-trimester ultrasound

In the first trimester of pregnancy, an early ultrasound is a routine part of prenatal care at 6 to 9 weeks, allowing parents a welcome first glance of their tiny baby bean. The American Congress of Obstetricians and Gynecologists (ACOG) recommends that all moms get a first-trimester ultrasound. It’s used to:
  • Confirm your estimated due date more accurately by measuring the fetus (after the first trimester, ultrasound measurements of the fetus are less accurate)
  • Confirm the fetal heartbeat.
  • Make sure the pregnancy is taking place where it’s supposed to, in the uterus (and to rule out a tubular or ectopic pregnancy)
  • Determine the number of fetuses
While most practitioners wait until at least 6 weeks to perform the first ultrasound, a gestational sac can be seen as early as 4 1/2 weeks after your last period; a heartbeat can be detected as early as 5 to 6 weeks (though it might not be detected that early in all cases).

Second trimester ultrasound

Midway through your pregnancy, usually between week 18 and week 22, a detailed anatomy scan called a level 2 ultrasound is performed. It’s generally done by a trained sonographer in a hospital or specialized clinic, where the equipment is more sophisticated. The second trimester ultrasound is not only fun for you to watch, it gives you and your practitioner a clear picture of the overall health of your baby and your pregnancy. It’s a way to:
  • See how baby’s developing and offer reassurance that everything is going exactly the way it should be, by measuring the size of your baby and checking all the major organs, measuring the level of amniotic fluid to make sure there’s the right amount, and looking at the location of your placenta
  • Tell you your baby’s sex, if you want to know
  • Give you a sneak peek at your baby (especially now that she looks like a baby!) — ask the sonographer to point out your baby’s hands, feet, face and tiny organs like the stomach and kidneys
Routine second trimester ultrasounds are usually done in 2D; most practitioners reserve the more detailed 3D and 4D ultrasounds for only when medically necessary, to more closely examine a fetus for a suspected anomaly, since there are mixed opinions on the safety of the ultrasound technology.

Additional ultrasounds during pregnancy

Sometimes a mom-to-be will have additional ultrasounds over the course of her pregnancy if she’s considered high-risk. If you have any spotting during pregnancy, your practitioner will usually perform an ultrasound to confirm that all is well. If you are carrying multiples, you will have frequent ultrasounds to monitor their growth.
You may receive an ultrasound to check for changes in the cervix (thinning, opening or shortening) if your doctor thinks you may be at risk of preterm labor.
Additionally, ultrasounds are a part of several other tests, including:

How an ultrasound during pregnancy is done

If you’re getting an ultrasound before week 6 or 7, your practitioner will likely perform a transvaginal ultrasound. A small, long transducer (or wand) is wrapped in a condom-like cover and sterile lubricant and inserted into the vagina. The practitioner will move the wand within the vaginal cavity to scan your uterus. The transducer emits sound waves, which bounce off structures (otherwise known as your baby) to produce an image you can see on a computer or video screen. You’ll be able to watch along with your practitioner (though you’ll likely need help to understand what you’re seeing). You can probably even take home a small printout as a souvenir.
Later on, you’ll get a transabdominal ultrasound examination, where a gel is rubbed onto your belly and then the wand is rubbed over your belly to produce images of your baby.
Ultrasounds can last from five to 30 minutes and are painless, except for the discomfort of the full bladder necessary for the first-trimester transabdominal exam. They can be somewhat uncomfortable if the sonographer needs to press hard on your abdomen to see a particular part of your baby more clearly.

The difference between sonogram and ultrasound

Though the words sonogram and ultrasound are often used interchangeably, there is a distinction. Ultrasound is the actual technology of using sound to produce sonogram pictures, including the one that you’ll take home.

Risks of ultrasounds during pregnancy

Ultrasounds are noninvasive and very low-risk. That said, medical guidelines caution against unnecessary exposure. Because no researcher would willingly put a fetus in harm’s way in the name of science, it’s difficult to study the long-term effects of ultrasound use — which means there is the possibility of unintended consequences with overuse. What’s more, though ultrasounds are usually relatively accurate at estimating a baby’s size, they can under- or over-estimate weight, especially if they’re overused, which may occasionally result in unnecessary C-sections or premature deliveries.
That’s why ACOG along with the Food and Drug Administration (FDA) urge practitioners and patients to only use ultrasounds if they’re medically necessary. These groups also recommend that pregnant women avoid keepsake 3-D and 4-D sonograms during pregnancy advertised by private companies along with at-home fetal monitors.

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