Ultrasound: How, When and Why?

By LMFM Staff on February 23, 2022

Baby’s first ultrasound: what an exciting time! It can be the first time you see the heart beating or when you can first count your baby’s fingers and toes. When you come for your scan, you may wonder why we schedule ultrasound appointments when we do, and what we are looking for as we monitor your pregnancy.

First of all, what is ultrasound?

  • Simply put, it’s a technique that uses high-frequency sound waves to generate images of the fetus’ body and internal organs.
  • It is considered to be a very safe diagnostic technique to help us monitor the baby’s growth and development.

Your sonographer will use one of two different techniques, depending on the timing and purpose of the exam:

  1. Transvaginal ultrasound: often used early in the pregnancy, it creates images via a smaller ultrasound probe inserted into the vagina.
  2. Abdominal ultrasound: this is the one most people think of when they hear that a pregnant person is having an ultrasound scan. A small amount of gel is applied to the abdomen, and the ultrasound transducer is moved over the surface of the skin.

Did you Know? Different types of ultrasound scans and testing will be done at different times during your pregnancy:

1. First trimester scans are done for a number of reasons. Some of the major ones are to:

  • Confirm your due date. We can get a better idea of when your baby is due by taking some measurements early in the pregnancy. That’s why it’s important to call for an appointment as soon as you know you’re pregnant. LMFM can do your early scans whether your pregnancy is considered high risk or routine.
  • Determine the number of fetuses. Twins? Triplets? We’ll be able to determine this with a first trimester scan. The earlier we know this, the sooner we can have a customized plan in place for your pregnancy.
  • Identify the structure of the placenta.
  • Check the anatomy of the pelvis and uterus. Everyone is unique!
  • Diagnose a miscarriage or ectopic pregnancy.
  • Check for certain fetal abnormalities (some will require scans later in pregnancy).

2. Mid-trimester ultrasound scans are typically done at 20-22 weeks and can verify information we obtained in a first trimester scan. They also perform these important functions, if needed:

  • Carefully check the fetus for abnormalities.
  • Monitor the growth of the fetus.
  • To check the activity of the fetus.
  • Examine the placenta, and to check for the number of fetuses.
  • Confirm the due date established in the first trimester.
  • Help guide your physician when performing tests such as amniocentesis.
  • Look at fetal blood flow patterns and heart function (fetal echocardiography). Our lead medical sonographer, Emily, explains it here: Fetal Echocardiography
  • To check the amount of amniotic fluid.
  • Measure the length of the cervix.

3. Third trimester ultrasound scans (we’re nearing the finish line!) are done to:

  • Monitor the growth, development and position of the unborn baby.
  • Assess the health and position of the placenta.
  • Check the amount of amniotic fluid.
  • Perform a biophysical profile (BPP) test, which assesses the fetus’ muscle tone, amniotic fluid, body movements, breathing movements and heart rate. For certain high-risk pregnancies, a BPP may be performed weekly during the third trimester.

What about 3D and 4D ultrasound?

Lancaster MFM’s diagnostic sonographers are all trained and certified to perform 2D, 3D and 4D scans. We use the latest equipment to get the clearest images and most accurate information.

  • 2D ultrasound is a cross section view through the baby, used to evaluate the fetal organs. All diagnostic ultrasound is performed in 2D.
  • A 3D scan is an image of the surface of the baby, most commonly the face. It can be used to evaluate abnormalities such as cleft lip and clubfoot.
  • A 4D scan shows a 3D image of the fetus moving in real time.

Whatever your needs, we can provide the most detailed imaging for your pregnancy.

We do not recommend the use of “keepsake” ultrasound, as these companies can sometimes give you a false impression of the health and wellbeing of your baby, because their employees do not have the level of training to properly do this.

If you have questions about ultrasound or need to schedule an appointment, please call or email us. We welcome self-referrals, and can perform scans for high-risk and routine pregnancies. We are always happy to hear from you.