I am pregnant with my first child. My doctor wants me to have an ultrasound in a few weeks. What happens during this test? Is it safe for my baby?
Ultrasound uses sound waves to create pictures of the fetus as it develops in the uterus. The ultrasound transducer, or probe, sends out high-pitched sound and then "listens" for the echoes that bounce back off the tissues in the body. A computer "translates" this information into ultrasound images, or sonograms, which can be seen on a video monitor.
During the test, you will lie on your back, and the doctor or ultrasound technician will squirt a clear gel onto your belly to help the transducer slide around easily. A picture will appear on a computer monitor, and the doctor or technician will move the transducer back and forth to see your baby from many different angles. The exam should not be painful.
Depending on your baby's age, the heart and other organs may be visible. Some images may look like nothing more than fuzzy black and white shapes to you, but a trained eye can see whether the chambers of the heart, for example, have formed normally. Sometimes, to better visualize an early pregnancy or look specifically at the lower part of the uterus and cervix, your doctor may recommend a transvaginal ultrasound. During this test, a probe with a sterile cover is placed inside the vagina.
Getting an ultrasound is usually exciting for a pregnant woman and her partner or family because they get a chance to see their growing baby. However, when an ultrasound becomes necessary because of a problem -- for example, when bleeding early in pregnancy raises concerns about a miscarriage -- it can trigger anxiety.
Doctors usually recommend having a fetal ultrasound to:
n Determine whether you might be carrying twins or triplets
n Estimate how far along your pregnancy is and when your baby might be born
n See how big your baby is and how quickly he or she is growing
n Make sure your baby's brain, spinal cord and other organs are developing normally.
Ultrasound can show some, but not all, birth defects.
For example, it can detect most cases of spina bifida -- a condition in which the spinal column doesn't close normally leaving the spinal cord open and exposed.
More subtle abnormalities may be missed, however.
Ultrasound can't detect problems that don't cause changes in anatomy: Something has to look different.
That's why ultrasound can't detect diseases like diabetes or sickle cell anemia.
Ultrasound can't tell for certain whether a baby has a genetic condition, such as Down syndrome.
But in some cases, it can detect subtle clues that will prompt doctors to perform other tests. Unless you have a bashful child who is lying with its legs crossed, ultrasound can discover your baby's sex.
Many women will have their first ultrasound between 18 and 20 weeks.
Women with problems such as bleeding or pain will have an earlier scan. If your doctor suspects you are having an ectopic pregnancy, meaning the fetus is developing in a fallopian tube instead of the uterus, you may get an ultrasound around the time you discover you are pregnant.
In the last part of pregnancy, if you have problems such as bleeding, high blood pressure, diabetes, too much or too little change in the size of your uterus or concern about too little fetal movement, your doctor might order additional ultrasounds.
Like you, many parents-to-be wonder about the safety of ultrasound. "Your Developing Baby," a recently published book filled with ultrasound images, should reassure you.
The authors say that it's a safe and valuable diagnostic medical procedure, because unlike X-rays and CT scans, ultrasound does not use ionizing radiation, which can damage fetal cells.
Ultrasound has been in widespread use for several decades. The American Institute of Ultrasound in Medicine and other professional organizations have documented no harmful effects of ultrasound in humans.
In fact, there is uniform agreement that the potential benefits of ultrasound justify its use for diagnostic purposes.
Remember that most fetal ultrasounds show a normally developing baby.
But in the rare case when a doctor spots a potential problem, ultrasound can be used to monitor the baby's condition or guide treatment while the baby is still in the uterus. For example, ultrasound has been used to guide a needle to give a baby a blood transfusion and perform prenatal heart surgery.
By getting an inside look at your unborn baby, you and your doctor will not only keep on eye on your child's health, but also witness the beginning of a new life.