Fetal Ultrasound

1 What is a Fetal Ultrasound?

An imaging technique which uses high-frequency sound waves to produce images of a baby in the uterus is called fetal ultrasound or sonogram.

These images can help you and your doctor to determine how your pregnancy is progressing and at the same time can evaluate your baby’s growth and development or in some patients they use this to evaluate if they have certain problems or to confirm a diagnosis.

To confirm that you are pregnant and date the pregnancy first fetal ultrasound should be done during the first trimester.

The next ultrasound will be in the second trimester of your pregnancy when anatomic details are visible but additional ultrasound will be needed if you have complications or problems with the baby.

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2 Reasons for Procedure

Here are the most common reasons to undergo a fetal ultrasound.

You and your doctor would want to evaluate the presence, number, location and size of the pregnancy that is why first-trimester ultrasound is done.

Ultrasound can also be used to screen for abnormalities of your cervix or uterus and for first-trimester sonographic genetic screening.

To evaluate several features of the pregnancy such as fetal anatomy, your doctor will conduct a standard ultrasound during the second or third trimester of the pregnancy which is mostly done between the 18th to 20th weeks of pregnancy.

But if you have conditions such as obesity or prior surgical incision at the scanning site, ultrasound may be altered.

When a specific question requires investigation there will be limited ultrasound evaluation during the second and third trimester.

These questions are the estimation of amniotic fluid volume or the evaluation of fetal growth.

Some of the possible reasons your doctor may want to use fetal ultrasound:

  • to confirm the pregnancy and its location – to check for ectopic pregnancy or pregnancy outside of the uterus because some fetuses develop in the fallopian tube
  • determine your baby’s gestational age – to check for various milestones throughout your pregnancy and to determine your due date
  • to confirm the number of babies
  • evaluate your baby’s growth – your doctor can check to monitor your baby’s movement, heart rate, and breathing and to determine whether your baby is growing at a normal rate
  • study the placenta and amniotic fluid levels – to check if there is too much or too little amniotic fluid or if there are complications with your placenta
  • to identify birth defects
  • to check for complications such as bleeding or other complications
  • to check the fetal position before delivery so that your doctor can discuss options for delivery
  • perform other prenatal tests such as chorionic villus sampling and amniocentesis

Fetal ultrasound is not just for knowing the gender of the baby or by producing keepsake pictures or videos, this is done only for valid reasons.

Discuss with your doctor about fetal ultrasound so that you can work together to determine what is best for your baby.

3 Potential Risks

Diagnostic fetal ultrasound generally carries no potential risks when used appropriately and this has been used during pregnancy for many years.

This provides an accurate assessment when the lowest amount of ultrasound energy is used.

The ones who are trained in the use of ultrasound energy are the ultrasonographers and the obstetric providers.

This is done only for medical reasons and not to create keepsake videos or pictures. Fetal ultrasound has limitations and this may not detect birth defects.

4 Preparing for your Procedure

To prepare for the fetal ultrasound, your doctor may ask you to avoid urinating and drink a certain amount of fluid depending on the type of ultrasound that you are having.

The fetal ultrasound can be done by:

  • transvaginal meaning through the vagina
  • transabdominal meaning over the abdomen

Consider wearing loose-fitting clothing so you can easily expose your abdomen if you are going to have a transabdominal ultrasound.

5 What to Expect

Read on to learn more about what to expect before, during, and after your fetal ultrasound.

The two types of the fetal ultrasound include:

  • transvaginal ultrasound – these are mostly done in the first trimester of pregnancy when the uterus and fallopian tubes are closer to the vagina, your doctor will insert a wand-like transducer inside your vagina that will send out waves and will reflect;
  • transabdominal ultrasound – your doctor will place a gel on your abdomen and will move the transducer over the area that can send out sound waves which will be interpreted by images that you can see on a monitor.

The other types of transabdominal ultrasound are:

  • Specialized sonographic evaluation – this is a more detailed evaluation that can be done when a fetal abnormality is known or suspected.
  • 3-D ultrasound – this is used by doctors to detect neural tube defects and facial abnormalities by providing photo-quality details.
  • Doppler ultrasound – this will provide details about your baby’s blood flow by measuring slight changes in the ultrasound waves as they bounce off moving objects.
  • Fetal echocardiography – this is used to rule out or confirm congenital heart defect by providing a detailed picture of a baby’s heart.

During the transabdominal fetal ultrasound, you will lie back on the table and will expose your abdomen. Your doctor will then apply a gel on the area.

The transducer will send out waves and receives those that bounce back. Your doctor will move the transducer back and forth and will be converted into images on a monitor.

He will measure your baby’s anatomy and he will give you copies of the images. You and your doctor may able to make out the face, hands or legs depending on the baby’s position and stage of development.

You will be asked to undress from the waist down or change into a hospital gown if you are going to have a transvaginal ultrasound.

You will lie down on a table with your two feet in stirrups and then he will place a lubricated transducer in your vagina.

After the exam, you can urinate if you had a full bladder or you can wipe off any residual gel or lubricant.

6 Procedure Results

If you do not understand your fetal ultrasound results, consult with your doctor.

You and your doctor can see if your baby is growing and developing normally in a fetal ultrasound.

Your doctor may suggest additional tests to check for more details about your baby’s health.