When ultrasound is used as a medical screening tool, there is little that can go wrong. As a diagnostic tool, ultrasound is highly accurate, because it uses a computer program that allows us to see detailed images of different organs. Therefore, an ultrasound scan can help us to diagnose medical conditions that may be affecting your baby, and it also helps us to plan for medical treatment of any detected abnormalities.
Ultrasound is a type of high-frequency sound wave that cannot be heard by the human ear. An ultrasound machine uses a transducer to transmit ultrasound waves to an organ or tissues that the doctor wants to visualize. The ultrasound waves are then reflected from the organ or tissue back to the transducer, producing a continuous image of the area. This image allows us to see whether there are abnormalities in the area and helps the doctor to diagnose any medical conditions that may be affecting your baby.
The clarity of the image depends on the distance of the organ from the transducer. If the organ is located close to the surface of the body, such as the liver, kidneys, or heart, then the ultrasound machine will be able to produce a detailed representation of it. However, if the organ is located deep within the body, like the womb or ovaries, water or fluid can help increase image clarity; so, if the doctor orders an ultrasound for the womb or ovaries, the patient needs to have a full bladder in order for the doctor to get a clear image of the area.
An ultrasound scan can be used to diagnose many types of conditions, because the machine can be used to scan every organ in the body. However, the most common uses of ultrasound in medical practice are cardiac ultrasounds, obstetrics ultrasounds, which is when a pregnant woman and her unborn child are scanned, and gynecological scans, which, in general, are scans of the female pelvis.
An ultrasound scan is beneficial in the practice of obstetrics and gynecology, especially for monitoring the development of infants in the womb, because it can help to calculate the exact gestational age of pregnancy. The woman’s period may have been altered, or she may not be able to remember when she had her last monthly cycle, so she may not know for sure the gestational age of her pregnancy. With ultrasound, however, the gestational age of pregnancy can be calculated with precision.
Doctors recommend that pregnant women should undergo a dating scan as soon as possible, no longer than three months after conception. This is because a dating scan is a useful tool in helping the doctor to monitor and observe the growth of the infant in the womb, and it allows us to see whether the child is small for its gestational age, or has any growth abnormalities.
Once the mother has entered her second trimester, the doctor will order an ultrasound scan to check the health of the baby, see whether he or she has any abnormalities or disabilities, and if so, determine how they might be resolved, and what treatment may be required once the baby is born. An ultrasound is an important diagnostic tool for both the mother and her child and gives the expectant parents a chance to plan for what lies ahead.
Another exciting by-product of an ultrasound scan is that it allows the expectant mother and father to find out the sex of their child. However, you will likely have to wait until around the fifth month of pregnancy before the sex can be determined accurately, doctors say.
Since ultrasound machines were introduced to medical practice, there have been no reports of dangerous side effects caused by ultrasound screening, regardless of its frequency of use.
Rather than how often ultrasound should be used, the important factor for the doctor to consider is whether an ultrasound scan is medically necessary based on the patient’s condition. Prior to each scan, the doctor will determine in what ways the patient is expected to benefit.
For general pregnancy scans, the doctor will usually order an ultrasound screening once a month. If the pregnancy requires closer monitoring, however, the doctor may order an ultrasound scan once every two weeks. Again, it depends on the circumstances of each patient.
There are certain limitations to the use of ultrasound, as there are some conditions for which screening does not work or sometimes the baby’s positioning in the womb means that the doctor is unable to produce a clear image for screening.
In its early days, ultrasound could produce only 2D images of an infant in the womb, showing only length and width. Later on, 3D imaging was developed, and with the introduction of depth, much more realistic images of the baby could be captured.
Today, 4D ultrasound is a new technology that uses modern software to produce a detailed, moving image of a baby in the womb. By collecting a series of 3D images and projecting each image onto a monitor in rapid succession, we can enjoy a moving picture of the baby, much like when we go to see a movie. 4D ultrasound allows us to see the baby’s face and all of its tiny details, and even allows us to observe the baby’s behavior during the scan. For example, the baby might move its face, lift its arms, raise its legs, move its fingers, or open its mouth. Parents will be very excited to see this on the big screen when they go for a scan.
Through the use of today’s ultrasound technology, doctors are able to monitor the health of the patient and the baby, all the while allowing for a strengthening of the bond between mother, father and baby.
M.D., Faculty of Medicine Siriraj Hospital, Mahidol University, 1992. , 1992
The Second Class Honors M.D., Faculty of Medicine, Thammasat University, 2006. Faculty of Medicine Thammasat University