Ultrasound Tests can provide valuable information for parents and health care providers to help manage and care for the pregnancy and fetus. In addition, ultrasound gives parents a unique opportunity to see their baby before birth, helping them to bond and establish an early relationship.
What is an ultrasound?
An ultrasound scan is a diagnostic technique which uses high-frequency sound waves to create an image of the internal organs. An ultrasound is usually performed during the course of a pregnancy to check fetal growth and verify the due date. Ultrasounds may be performed at various times throughout pregnancy for different reasons:
In the first trimester
- To establish the dates of a pregnancy
- To determine the number of fetuses and identify placental structures
- To diagnose a miscarriage or ectopic pregnancy
- To examine the pelvic anatomy and uterus
- To detect fetal abnormalities (for those who need genetic screening)
Mid-trimester (sometimes called the 18 to 20 week scan)
- To confirm pregnancy due date
- To monitor fetal growth
- To determine the number of fetuses and examine the placental structures
- To assist in prenatal tests, such as an amniocentesis
- To measure the length of the cervix
- To examine the fetal anatomy for presence of irregularities / abnormalities
- To check the quantity of amniotic fluid
- To examine blood flow patterns
- To observe fetal behavior and activity
- To examine the placenta
- To monitor fetal growth
- To check the amount of amniotic fluid
- As part of the biophysical profile
- To determine the position of a fetus
- To assess the placenta
How is an ultrasound scan performed?
Two types of ultrasounds can be performed during pregnancy:
In an abdominal ultrasound, gel is applied to the abdomen and the ultrasound transducer glides over the gel on the abdomen to create the image.
In a transvaginal ultrasound, a smaller ultrasound transducer is inserted into the vagina and rests against the back of the vagina to create an image. A trans-vaginal ultrasound produces a sharper image and is often used in the early stages of pregnancy.
2D, 3D or 4D Ultrasound?
There are several types of ultrasound scanning techniques. The most common is 2D ( two dimensional ), which gives a flat picture of one aspect of the image.
If more detailed information is required, a 3D ultrasound examination can be performed. The 3D Ultrasound requires a special machine and special training. Added advantages of the 3D image includes the ability of the health care provider to see width, height, and depth of images, which can be helpful in diagnosis. The 3D images can also be captured and saved for later review.
The latest technology is 4D ultrasound, which allows the radiologist to visualize the unborn baby moving in real-time. With 4D imaging, a three-dimensional image is continuously updated, providing a “live action” view. These images often have a golden color, which helps show shadows and highlights.
What are the risks and benefits of ultrasound?
Fetal ultrasound has no known risks other than mild discomfort due to pressure from the transducer on the abdomen or in the vagina. No radiation is used during the procedure.
Transvaginal ultrasound requires covering the ultrasound transducer in a plastic/latex sheath, which may cause a reaction in patients with a latex allergy.
Fetal ultrasound is sometimes offered in non-medical settings to provide keepsake images or videos for parents. While the ultrasound procedure itself is considered safe, it is possible that untrained personnel may give parents false assurances about their baby’s well-being, or perhaps an abnormality may be missed. Having ultrasound performed by trained medical personnel who can correctly interpret findings is recommended.