Pregnancy Ultrasound: Procedure & Preparation


The purpose of an ultrasound is to determine the location and characteristics of your baby’s organs and organs during pregnancy. The ultrasounds can be used to detect any abnormalities, and to measure the growth and development of the baby.

Purpose of an ultrasound?

Purpose of an ultrasound

Each baby has distinct markings on their skin as well as unique facial features and size. You can view these pictures of your baby’s insides to determine if you are carrying a girl, a boy, or an uncooperative baby. If you see a flaw or abnormality, you can get more help from your OBGYN during this pregnancy.

However, if you don’t see anything, it is best to get this done around 20 weeks of pregnancy. Pregnancy ultrasounds are performed at around 15 weeks of pregnancy. These tests can help your doctor to diagnose the condition of the baby’s heart.

If the placenta is delivering adequate oxygen and nutrients to the baby. Your doctor may also be able to tell your baby’s sex by performing an ultrasound.

Possible risks

Possible risks

An ultrasound can be performed at any stage of pregnancy. However, some women may have more of a risk of experiencing complications with an ultrasound. A common risk is the radiation from the ultrasound machine. Some research suggests that ultrasound radiation increases the risk of breast cancer. However, most doctors believe that a risk is small. Your doctor may also order an ultrasound if a previous ultrasound did not detect a baby’s sex, when a placenta is providing an abnormal amount of blood to the baby, or to check the health of your baby in other ways. In some cases, the doctor may perform an ultrasound if there is a medical concern. These may include:

  • Seeing if the umbilical cord is attached to the baby.
  • Checking for conditions in your cervix, such as a polyp or infection that could affect the baby.
  • Notifying the mother if there is a condition that the ultrasound could help to diagnose.

If a woman is experiencing pregnancy complications, her doctor may recommend that she should get an ultrasound at any stage of pregnancy to monitor her health. In some cases, this may be necessary for a mother to receive antepartum treatment for severe morning sickness.

Other kinds of ultrasounds

Other kinds of ultrasounds

Different types of ultrasounds are used in different situations.

Most of these ultrasounds use sound waves. The doctor places the ultrasound device on the skin of your abdomen and looks for a target on your baby’s body. The target is called the vessel.

Types of sound waves

There are several types of sound waves that are commonly used for ultrasounds. The doctor places a probe on the skin of your abdomen.

Positive pressure ultrasound (PPUS)

A probe is placed on your abdomen that creates an electrical field to change the shape of the uterus, which expands the volume of your uterus.

Femto-ultrasound (FUS)

The doctor creates an image using sound waves that travel through the amniotic sac.

Electrical conductivity ultrasound (ECUS)

The doctor places the ultrasound device on your abdomen and creates an electrical field to alter the position of the fetus, which can help the doctor determine fetal position and the position of the placenta.

Perimeter ultrasound (PRAM)

The doctor uses an ultrasound probe that has a thin, flexible probe attached to it. The probe is placed on the skin and looks for an indentation in the skin. It’s used to get different kinds of images.

Morphological ultrasound (MUR)

The doctor uses an ultrasound probe to create an image by looking at the external features of the body, which include the bones, muscles, internal organs, and blood vessels.

Fluidics ultrasound (FLUS)

The doctor uses a probe that is held in place on the skin. The probe uses ultrasound waves to help detect movement within the body.

What is a fetal fibronectin test?

The fetal fibronectin test is used to screen for potential birth defects. The fetus’s antibodies bind to the fetal fibronectin protein on the cell surface. The test is done to monitor the absorption of the fibronectin protein in your blood and the integrity of your placenta.

What is a transvaginal ultrasound?

Transvaginal ultrasound is the term for one-dimensional sonography performed on the vaginal or cervix. The test helps the doctor locate your baby’s body and organs during pregnancy. A transvaginal ultrasound is performed at a clinic, hospital, or other facility and usually involves your doctor inserting a probe into the vagina. It is performed using an ultrasound device that has a thin, flexible probe. After the probe is inserted, it enters the vagina and passes over the external walls of the vagina.

The doctor then uses a wand to send ultrasound waves into the vagina to produce an image. Most doctors also use a transrectal probe, which is a probe that is inserted into the rectum. If your doctor orders a transvaginal ultrasound or transrectal ultrasound, you may need to drink a cup of warm or cold water. The water is intended to be used to wash the probe from your vaginal walls. This helps the doctor keep it clean and reduces the chances that any urine will reach the probe.

Several things may affect the image quality of the ultrasound

Several things may affect the image quality of the ultrasound

Your doctor may recommend waiting to use a vaginal ultrasound if you have had a vaginal or pelvic exam for the previous 12 months. If you have had a vaginal or pelvic exam for the previous 12 months, your doctor may want you to lie on your side, or recline on a chair with your legs raised.

The doctor may need to change the angle that the probe is inserted into the vagina, which may cause additional discomfort. A transvaginal ultrasound will usually take less than 15 minutes. A transrectal ultrasound can take longer because the probe may be inserted into the rectum.

How to prepare for a vaginal ultrasound

Because a vaginal ultrasound is used to take pictures of the genitals of the mother, the baby, and the uterine lining, it may be important for a woman to drink a lot of water and drink more frequently between the time that she begins to drink and the time that she has to go to the bathroom.

You may be able to drink something with a bit of carbonated juice and mint or soda water, but never carbonated soft drinks as they are high in sugar. If you are already feeling thirsty before the ultrasound, add more water and slowly add something a bit sweet.

Why are ultrasounds taken during pregnancy?

During the second and third trimesters Ultrasounds may be done to confirm pregnancy. Check for fetal defects (i.e., neural tube defects, cleft lip and/or palate, spinal defect, heart defects, Down syndrome, or anencephaly)

Determine the gestational age of the baby and estimate a due date, check for multiple pregnancies, examine the placenta, uterus, ovaries, and cervix. Examine the fetus for physical abnormalities (i.e., anencephaly, neural tube defect, cleft lip and/or palate, spina bifida, etc.)

Identifying the best type of ultrasound for your baby depends on your individual needs, symptoms, and timing of your pregnancy, for a healthy pregnancy and healthy baby your healthcare provider may recommend you have a non-stress test (NST) at home (either alone or with the baby) during the second trimester if you are having repeated episodes of early contractions and/or vaginal bleeding.

At this point, the baby is usually moving and kicking a lot and looks good, but your baby is a bit too active for the heart to follow the sounds to the heart so it may skip beats. This is normal and usually resolves itself by the end of the day.

If the NST fails to result in an optimal heart rate or contractions return with time (but less frequently), your healthcare provider may recommend you return for a more detailed test (such as an ultrasound).

Always follow your healthcare provider’s instructions for each test. If the results indicate the baby is not moving as much, it may be necessary to use medication to slow the baby’s heart rate and contractions. Or a Doppler ultrasound may be recommended (Ultrasound-Doppler Ultrasound is similar to a regular ultrasound, except it measures the movement of the baby to see if the heart rate is normal).

Potential risks to understand

It’s also important to understand the potential risks associated with a diagnostic ultrasound, including an elevated risk of miscarriage and of birth defects, such as spina bifida or cleft lip and palate, or perinatal hypoxia, which is a low oxygen level at birth.

If your baby has been exposed to a diagnostic ultrasound in utero, your healthcare provider will advise you on the best time and method to deliver your baby. Some women prefer to have their babies delivered in the operating room in order to minimize the risk of trauma to the infant and complications for you. A C-section can also be needed if the baby has stopped moving, or if your healthcare provider has reason to suspect that your baby may be in distress. Remember, the more you know about your pregnancy, your options for care, and the safety and well-being of your baby, the more confident you will feel about your choice of care.

How to prepare your body for a ultra sound process?

You may need to drink water between the time that you begin drinking and the time that you are going to have to go to the bathroom to give the technician a clear picture.

What happens to you during an ultrasound?

What happens to you during an ultrasound

The technician uses an ultrasound machine to take a series of pictures of your belly. Depending on the stage of your pregnancy, your belly may be examined from different angles, too. You’ll often hear an audible clicking sound while the machine captures images of your baby.

Your ultrasound technician will ask you a series of questions to determine your due date. Usually, they’ll ask you how far along you are in your pregnancy, how many weeks along you are, and your blood type.

Your technician will use a special wand to move the gel around your stomach and check for a heartbeat and other measurements. They’ll print out the results and share them with you.

Your ultrasound technician will often ask you to drink a water bottle-sized amount of water so your baby is more visible on the ultrasound.

The technician will ask you to lie on your back with your legs together and place your left hand on your belly. If you have your baby in your left arm, you’ll feel a subtle difference from the left arm to the right.

The technician will aim the ultrasound wand over your stomach and zoom in on your baby. They’ll point out your baby’s heart beat and measure it to be approximately 120-130 beats per minute (bpm).

More about Ultrasound

They’ll also measure the amount of amniotic fluid that your baby has in their sac.

The technician may measure your baby’s head size and nose length.

You may be asked to move around on the bed to see different parts of your baby on the screen.

Sometimes, your technician may zoom in on certain body parts of your baby such as their eye sockets or fingers.

If your baby is engaged in her or his movements and the technician can see them moving, they’ll say so by tapping your belly or pressing the belly button.

If your technician cannot see your baby moving or there is no movement, they’ll perform a non-stress test.

At this time, the technician will move the probe around your belly to see your baby’s heart rate.

They’ll also check your baby’s movement with movements of their arms and legs. If there is no movement, the technician may put their ear on your baby’s chest and listen to their heartbeat.

The technician will also measure the umbilical cord flow.

Lastly, your technician may also measure your baby’s length to determine if your baby is a healthy size.

If you’re worried or having symptoms

Baby may be having a problem, ask the technician to check for the following:

  • Blood flow or responsiveness
  • Labor contractions
  • Heart beat variability
  • Choroid plexus cysts
  • Intrauterine growth restriction
  • Placental abruption

Bottom line

Doctors usually try to avoid transfer unless the possibility of the baby having an issue is very high. If your baby has a strong heart rate, they’ll do an ultrasound to make sure they are not in distress and your ultrasound results will determine when you go to labor and delivery. It is common for doctors to do an ultrasound with the NST during their first prenatal appointment. If you had a high heart rate or other indication that your baby may be in distress, your doctor will perform a more thorough ultrasound after your first prenatal appointment.