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What is ultrasound? How does ultrasound work? Why is an ultrasound done? What will happen during the ultrasound? What can an ultrasound find? Does a normal ultrasound mean I will have a healthy baby? Is ultrasound safe? What are the benefits of ultrasound? How is ultrasound used in women's health care? How is ultrasound used during pregnancy? How many ultrasound exams will I have during my pregnancy? Where is an ultrasound exam done? Who performs the ultrasound exam? What type of ultrasound exam will I have? What do I need to do to prepare for a transabdominal ultrasound exam? What happens during a transvaginal ultrasound exam? What is a specialized ultrasound exam? What are the types of specialized ultrasound exams? What is Doppler ultrasound? What are 3D and 4D ultrasound? What is sonohysterography? What are the risks of ultrasound exams? |
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What is ultrasound?
Ultrasound is energy in the form of sound waves. The most common type of ultrasound exam is called two-dimensional (2D) ultrasound. In this type of ultrasound, a transducer sends sound waves through the body. The sound waves hit tissues, body fluids, and bones. The waves then bounce back, like echoes. The transducer receives these echoes, which are converted into images of the internal organs and—during pregnancy—the fetus. Ultrasound comes from a machine that creates an image of the inside of your body. It shows what your baby looks like while still inside your womb (uterus). Ultrasound can tell you—and your health-care provider—many things about your baby, such as: • the size of the baby • how well the baby’s heart works • how well other organs (such as the spine, brain and kidneys) are growing • the anticipated date of birth The moving pictures from the ultrasound machine are like a movie. The pictures appear on a computer screen. How does ultrasound work? Ultrasound pictures are made from sound waves which are too high pitched to be heard by the human ear. The sound waves travel through your skin and are focused on a certain part of your body by a scanning device called a “transducer.” It picks up the sound waves as they bounce back from organs inside the body. Ultrasound is different from x-rays because it does not use radiation. This makes it safer for you and your baby. Ultrasound is used in many areas of medicine. Why is an ultrasound done? An ultrasound can help to check on many aspects of a healthy pregnancy, such as: • the number of babies • whether the baby ’s size is right for his/her age • how the baby’s internal organs are growing • whether the placenta (afterbirth) is in the correct place • whether there are problems with the mother’s uterus, fallopian tubes or ovaries Experts in Canada recommend that all women have an ultrasound when they are pregnant. The best time to do this is between 18 and 22 weeks of pregnancy. You might be asked to have ultrasound at other times during your pregnancy. Your health-care provider may suggest this: • to see what position the baby is in • to check the placenta (afterbirth) • to view how much fluid is around the baby • to check the baby’s growth and well-being • to check for signs of a possible genetic problem What will happen during the ultrasound? Before you go for an ultrasound, you will get information on how to prepare and where to go. Sometimes, women are told to arrive with a full bladder, but not so full it causes pain. This helps the sound waves travel better through the skin and tissues. You may be asked to change from your own clothing into a medical gown. The person who does the ultrasound is called an ultrasonographer. Once you are lying down on the examining table, clear gel will be put on your skin. The gel allows the transducer to move easily on your skin and helps the sound waves to transmit into your body. You may feel light pressure on your tummy but no pain. An ultrasound exam takes about 30 minutes. If more tests are needed, it could take longer. Sometimes, the ultrasound must be done through the vagina (birth passage). A special kind of transducer is placed into your vagina. Most women feel no pain during this type of ultrasound. What can an ultrasound find? You should make sure you are fully informed about why you are having an ultrasound. It is an important way to learn about problems. The results of an ultrasound may mean you will need to have more tests. Talk to your health-care provider before you have an ultrasound to make an informed decision. For most pregnant women, ultrasound assures them that their baby is healthy and all is well. Sadly, for a few, the ultrasound will find signs that all is not normal. Remember that the screening test only indicates an increased chance for concern and cannot tell you for sure if the baby does have a specific condition. Your health- care provider will be told if the ultrasound shows any signs of abnormality. They will discuss this with you. You may be referred to a centre that has expert doctors with experience in the field of fetal abnormalities. Does a normal ultrasound mean I will have a healthy baby? Ultrasound can detect many, but not all, abnormalities. Finding an abnormality depends on many factors, including the age and position of the baby, as well as the size and type of abnormality. The clarity of the pictures depends on the ultrasound equipment and how well the ultrasound can pass through the mother’s abdomen. For example, ultrasound will be less clear when the mother’s abdomen is thick or scarred. Is ultrasound safe? Ultrasound has been used on pregnant women for more than 30 years. Studies continue to make sure ultrasound is safe. So far, there is no reason to think that it harms mothers or babies. As with all medical tests, the benefits must always be greater than the risks. Health Canada regulates ultrasounds in Canada through two laws: the Medical Devices Regulations of the Food and Drugs Act and the Radiation Emitting D evices Act. This helps to ensure that ultrasounds are safe when used for medical reasons. The Society of Obstetricians and Gynaecologists of Canada and Health Canada have produced guidelines on diagnostic ultrasound. They state that ultrasound should not be used for any of these reasons: • to have a picture of the baby, solely for non-medical reasons • to learn the sex of the baby, solely for non-medical reasons • for commercial use, such as trade shows or making videos of a baby What are the benefits of ultrasound? Ultrasounds provide pregnant women with important medical information. It helps Canadian women have healthy babies. Ultrasound must be used carefully to ensure that mothers and their babies benefit from what it offers. If your health-care provider recommends that you have an ultrasound, make sure you know: • why it is needed • the risks that may be involved • how it will be done How is ultrasound used in women’s health care? Ultrasound can be used to diagnose and monitor certain problems, such as a pelvic mass, a breast lump, abnormal bleeding, pelvic pain, or infertility. It also can be used during pregnancy to monitor the fetus. How is ultrasound used during pregnancy? Ultrasound is used during pregnancy to find out whether the growing fetus inside your uterus is developing normally. It can be used to check the anatomy of the fetus for defects or problems. It also can be used to find out the following information: • Age of the fetus • Location of the placenta • Fetal position, movement, breathing, and heart rate • Amount of amniotic fluid in the uterus • Number of fetuses Ultrasound may be used to screen for certain birth defects, such as Down syndrome. Ultrasound also is used during chorionic villus sampling and amniocentesis to help guide these procedures. How many ultrasound exams will I have during my pregnancy? You may have at least one standard exam during your pregnancy. This ultrasound exam usually is performed at about 16–20 weeks of pregnancy. Some women may have an ultrasound exam in the first trimester of pregnancy. If a problem occurs during pregnancy, such as bleeding or pelvic pain, ultrasound may be used to help find the cause. Where is an ultrasound exam done? An ultrasound exam may be done in a health care provider’s office or a hospital. Who performs the ultrasound exam? It may be performed by your health care provider or a specially trained technician. How is the ultrasound exam performed? During an ultrasound exam, the transducer is either moved across your abdomen (transabdominal ultrasound) or placed in your vagina (transvaginal ultrasound). What type of ultrasound exam will I have? The type of ultrasound exam you have depends on what types of images your health care provider needs and why the exam is being done. If you are pregnant, it also depends on how far along you are in your pregnancy. Transvaginal ultrasound often is used in early pregnancy. Transabdominal ultrasound often is used after about 10 weeks of pregnancy. Your weight also can determine which type of exam is needed. What do I need to do to prepare for a transabdominal ultrasound exam? If you are having a transabdominal ultrasound exam, wear loose-fitting clothes. This will allow your abdomen to be exposed easily. You may need to drink several glasses of water during the 2 hours before your exam. This will make your bladder full. A full bladder is helpful because sound waves pass more easily through liquid than through air. What happens during a transabdominal ultrasound exam? For this exam, you will lie on a table with your abdomen exposed from the lower part of the ribs to the hips. A gel is applied to the surface of the abdomen. This improves contact of the transducer with the skin surface. The handheld transducer then is moved along the abdomen. What happens during a transvaginal ultrasound exam? For a transvaginal ultrasound exam, you will be asked to change into a hospital gown or undress from the waist down. You do not need to fill your bladder before the test. You will lie on your back with your feet in stirrups, like for a pelvic exam. The transducer for this exam is shaped like a wand. It is covered with a latex sheath, like a condom, and lubricated before it is inserted into the vagina. What is a specialized ultrasound exam? A specialized ultrasound exam often uses additional technology to examine a particular organ. If your health care provider suspects a problem based on other tests, you may have a specialized ultrasound exam. What are the types of specialized ultrasound exams? Specialized ultrasound exams include Doppler ultrasound, three-dimensional and four-dimensional (3D and 4D) ultrasound, and sonohysterography. What is Doppler ultrasound? This test is done during pregnancy using transabdominal ultrasound. Sound waves are used to measure blood flow in the fetus’s umbilical cord or other blood vessels. It also can be used to listen to the heartbeat. A health care provider may order this test if the fetus is not growing normally or with other tests to detect fetal anemia. What are 3D and 4D ultrasound? In a 3D ultrasound exam, multiple 2D images are taken at various angles. The images then are assembled into a 3D image. A 4D image is similar to a 3D image, but it shows movement. A 3D or 4D ultrasound sometimes is done when a specific problem is suspected during pregnancy, such as a problem with the placenta or fetus. What is sonohysterography? This test is used to look for problems within the uterus, often as part of an infertility evaluation. For sonohysterography, you first have a transvaginal ultrasound exam. Next, a catheter (a thin tube) is inserted through the cervix. A saline solution (salt water) is injected through the catheter into the uterus. The saline makes the inside of the uterus easier to see with ultrasound. What are the risks of ultrasound exams? Currently, there is no reliable evidence that ultrasound is harmful to a developing fetus. No links have been found between ultrasound and birth defects, childhood cancer, or developmental problems later in life. However, it is possible that effects could be identified in the future. For this reason, it is recommended that ultrasound exams be performed only for medical reasons by qualified health care providers. Glossary Amniocentesis: A procedure in which a needle is used to withdraw and test a small amount of amniotic fluid and cells from the sac surrounding the fetus. Amniotic Fluid: Water in the sac surrounding the fetus in the mother’s uterus. Anemia: Abnormally low levels of blood or red blood cells in the bloodstream. Cervix: The lower, narrow end of the uterus at the top of the vagina. Chorionic Villus Sampling: A procedure in which a small sample of cells is taken from the placenta and tested. Down Syndrome: A genetic disorder caused by the presence of an extra chromosome and characterized by intellectual disability, abnormal features of the face, and medical problems such as heart defects. Fetus: The developing organism in the uterus from the ninth week of pregnancy until the end of pregnancy. Placenta: Tissue that provides nourishment to and takes waste away from the fetus. Sonohysterography: A procedure in which sterile fluid is injected into the uterus through the cervix while ultrasound images are taken of the inside of the uterus. Transabdominal Ultrasound: A type of ultrasound in which a device is moved across the abdomen. Transducer: A device that emits sound waves and translates the echoes into electrical signals. Transvaginal Ultrasound: A type of ultrasound in which a device specially designed to be placed in the vagina is used. Trimester: One of the three 3-month periods into which pregnancy is divided. Ultrasound: A test in which sound waves are used to examine internal structures. During pregnancy, it can be used to examine the fetus. Umbilical Cord: A cord-like structure containing blood vessels that connects the fetus to the placenta. Uterus: A muscular organ located in the female pelvis that contains and nourishes the developing fetus during pregnancy. |