Ultrasound is useful throughout pregnancy. Most women have at least one ultrasound exam.
You will need to have a full bladder for most ultrasounds. You will be required to partially undress, and it's possible a vaginal ultrasound may be performed.
For your comfort and privacy, please only invite friends and family you feel comfortable undressing in front of, as the exam must be performed on bare skin.
Your maternal-fetal medicine physician will discuss your ultrasound results with you.
Types of Ultrasounds
First Trimester Dating Ultrasound (less than 14 weeks)
- A dating ultrasound will be performed when you begin prenatal care with a CHI Health clinic.
- Identify multiple pregnancies (twins, triplets, etc.)
- Identify risk for Down syndrome and other chromosomal abnormalities
- Assess uterus for fibroids
Second Trimester (20 Weeks)
Depending on fetal position, it may be possible to find out your baby's sex at this appointment. If you are having twins, this ultrasound will take twice as long.
- Confirm gestational age
- Determine fetal sex
- If a multiple gestation, determine how many placentas and gestational sacs there are
- Scan anatomy - head, heart, stomach, intestinal tract, kidneys, spine, arms & legs
- Observe fetal movement
- Determine placental location, cervical length, amniotic fluid volume
- Assess baby’s position and heart rate
- Screen for Down syndrome and other genetic abnormalities
Third Trimester
- Determine estimated weight and position of baby
- Examine location of placenta, amount of amniotic fluid
- Assess fetal heart rate
- Assess length of cervix
After 40 Weeks
- Assess amniotic fluid volume, location of placenta
- Determine position of baby
3-dimensional Ultrasound
- Determine severity and prognosis of suspected birth defect
- Not always possible, depending on your baby’s position
Transvaginal Ultrasound
This pelvic ultrasound is often a better way to look at the Fallopian tubes, ovaries, and cervix. A transvaginal ultrasound is performed for many different reasons. It's used to evaluate abnormal bleeding or abnormal findings on an exam. It can also be used to look at a very early pregnancy or diagnose an ectopic pregnancy.
You will start with an empty bladder. You will undress from the waist down and then lay on the table. A cover will be placed over the probe or the wand and then inserted into the vagina. A series of pictures or images will be taken. The procedure takes about 10 minutes. You will feel some mild pressure but no pain, and the results are immediate.
Amniocentesis
Under ultrasound guidance, a needle is inserted into the amniotic sac to withdraw a small amount of amniotic fluid. This is generally done between 15 and 18 weeks of pregnancy, but can be done up to 36 weeks in some cases. This procedure assesses for:
- Fetal genetic abnormalities
- Signs of certain infections
For 24 hours after the procedure, you should stay off your feet as much as possible and drink extra fluids. You’re asked to avoid exercise, heavy lifting, and sexual activity.
Minor bruising or soreness where the needle was inserted and mild cramping can occur for several hours. Watch for vaginal bleeding, loss of amniotic fluid, cramping lasting more than 3-4 hours or chills or fever of more than 100.6. A very small risk of miscarriage is associated with amniocentesis.
Fetal Echocardiography
This test is performed most often at 22-24 weeks to take a closer look at your baby’s heart. Sometimes, baby’s position can hinder our ability to complete a detailed heart evaluation. The specialized diagnostic test assesses:
- Heart size, position, and function
- Blood flowing into and out of the heart
- Heart rate and rhythm
Maternal conditions that indicate need for fetal echocardiography:
- Diabetes
- Family history of heart disease
- Exposure to drugs, alcohol, or certain medications
Fetal reasons that indicate need for fetal echocardiography:
- Abnormal cardiac screening examination
- Abnormal heart rhythm
- Suspected chromosomal abnormality (Down syndrome)
- Identical twins