Pregnancy Ultrasound Scan
Scans At Each Trimester Explained

Trimester Scans

Ultrasounds While Pregnant

Ultrasound Scans


What Is An Ultrasound Scan?
When Do I Need One?
Why Do I Need It?
What Happens During The Procedure?
Are Ultrasounds Safe?
How Much Does It Cost?

Pregnancy Care

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Prenatal Care Guide

What Is An Ultrasound?

This is one of the simplest and most pain-free screening tests you can have carried out during your pregnancy. Ultrasound is a diagnostic technique in which high frequency sound waves are passed into the body and the reflected echoes are used to build a picture of the internal organs and fetus.

When Do I Need One?

Most women have an ultrasound in their first trimester of pregnancy typically before week 15. Sometimes a scan can be repeated at 18-22 weeks to ensure all is progressing well with the pregnancy. This next scan is known as an anatomy scan, and is used to check in more detail for any fetal abnormalities.

Why Do I Need It?

A first trimester ultrasound, usually a basic level 1 ultrasound, is carried out to:

• Confirm the viability of a pregnancy.
• Confirm the date of pregnancy.
• Check for ectopic pregnancy (an embryo outside of the uterus).
• Check the amount of amniotic fluid in the uterus.
• Check the age, size and growth rate of the fetus (intrauterine growth restriction).
• Determine how many fetuses there are. If you are pregnant with twins, this is the first time you are likely to find out!
• Check for major fetal birth defects such as spina bifida as well as minor abnormalities like cleft palate or clubfoot.

Where a mother is advised by a counselor to carry out genetic testing during pregnancy, a first trimester scan may be used in combination with an amniocentesis test or CVS test (chorionic villus sampling test).

Tip: How accurate is a scan at predicting gender?

What Happens During The Procedure?

There are basically two methods of ultrasounds which are used for pregnant women: A transvaginal ultrasound and a transabdominal ultrasound.

Transvaginal Ultrasound

A transvaginal scan is usually the scan of choice in the first trimester. The reason being, it shows more detailed images than a traditional belly scan. Given the fetus and it's heartbeat is so small and difficult to spot at this stage, every pixel counts! During the scan the woman lies on a table, knees bent and feet held in stirrups. A transducer, coated in a condom and gel, is inserted into the vagina. The probe sends out sound waves with which pictures are created immediately on a monitor. The test is painless, as only a small part of the probe is inserted. The only discomfort may be the necessity for a full bladder for the procedure.

Transabdominal Ultrasound

This technique is usually used for the second trimester scan as it is more targeted. The patient removes all clothing around the lower belly and gel is smeared to the area to ensure good contact between the skin and transducer (the device that emits the ultrasonic waves). The transducer is placed on the belly and is rolled back and forth while internal images can be seen on a monitor next to the technician. This procedure is also commonly used for women with gynecological disorders such as uterine fibroids and infertility issues. Again, the test is painless and the only discomfort might be the necessity for a full bladder. The procedure may be carried out by a member of your pregnancy healthcare team such as your OB/GYN or doctor or a specially trained technician.

What Other Types of Ultrasound Are There?

Doppler Ultrasound: Performed in the same way as a transabdominal ultrasound, it uses uses a modified, higher intensity sound wave (known as the Doppler Effect). Doppler scanning can be used to monitor fetal heartbeat and to obtain information about the rate of blood flow in the blood vessels, for example through the fetus umbilical cord. This helps identify if the fetus is in any distress and the likelihood of pregnancy complications.

Sonohysterography: A transvaginal ultrasound exam is carried out as normal. Then a catheter (a small tube) is inserted through the cervix and a saline solution is injected through it. The solution bloats the uterus so that abnormal findings appear more obvious.

3D Image and 4D Video Ultrasound: A form of transabdominal ultrasound where images are created and stored. Also referred to as prenatal imaging and the individual images are called sonograms.

Second Trimester Ultrasound Scan

This scan is usually carried out between weeks 18-22 of the second trimester of pregnancy. This level 2 or targeted ultrasound gives a more detailed scan of the fetus. It is also a lot more fun than the first scan because the baby is bigger and you can see so much more. A level 2 scan is usually carried out via the transabdominal procedure. You may be able to spot your baby's heartbeat, face, arms and legs. Sometimes you can make out the baby's gender, so if you would like to keep this a surprise, be sure to tell your doctor first. If a 3D/4D ultrasound is also carried out, you will be able to bring home a picture or video of the scan. See also: Ultrasound scan photos and video images.

Third Trimester Ultrasound Scan

Generally most women are only offered 2 scans (although you may be offered an additional scan at week 12 called a nuchal scan). A third trimester ultrasound may be advised however where there is some concern over placental location, fetal movement/presentation or to identify uterine and pelvic abnormalities in the mother. Other reasons could include, you are carrying twins, the umbilical cord was tied around the baby's neck in an earlier scan or the baby appears smaller than it should be for its gestational age. See also: Third trimester prenatal visit.

Are Ultrasounds Safe?

No known risks are associated with scans, but there are lots of benefits. The only disadvantage appears to be their inaccuracy, where a 'potential' issue is highlighted, but is in fact quite normal. For example 'soft markers' are detected during 5 to 10 percent of second trimester scans - these are subtle characteristics which may indicate risk of chromosomal problems (such as Down syndrome or trisomy 18). However, these characteristics are also found in plenty of babies who are born perfectly healthy. So although technology is a wonderful thing, it can also be the cause of unnecessary stress and worry. There have been suggestions that scanned babies may be more likely to be left-handed, dyslexic or slow to speak. However, these concerns remain unproven. Still, most experts advise that ultrasounds be used in pregnancy only where valid reasons exist.

How Much Does It Cost?

If you do not have maternity insurance coverage, you may need to pay the full cost of an ultrasound yourself. The average cost of medical care for a full-term pregnancy in America is about $10,000 (see prenatal care costs). You should expect to pay about $270 to $360 for an ultrasound, depending on the State you live in.

  Related Articles on ULTRASOUND SCANS

For more information for moms-to-be, see the following:

Guide to Childbirth - Stages of labor, epidural pain relief explained and induction procedures and techniques.
Maternity Clothes - Fitting your new pregnant shape.
Doula - Birthing services for expectant women.
Paternity Testing - Guide to the tests available.
What tests do you need during pregnancy?

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