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While each pregnant person’s situation is unique, there are some commonalities to the use of ultrasound as the pregnancy progresses. When used in medicine, the technology uses sound waves to develop pictures of the fetus during pregnancy, to determine size, identify anatomical features of the fetus, and sometimes measure blood flow and amniotic fluid levels, among other uses.
Categories timing of pregnancy ultrasounds
Typically, healthy pregnant patients receive two ultrasound exams, one during the first and one during the second trimester. Additional scans may be performed when the clinician feels they are necessary. The American Congress of Obstetrics and Gynecologists (ACOG) categorizes ultrasounds during pregnancy as standard, limited and specialized.
Standard fetal ultrasound: The standard fetal ultrasound checks fetal physical development, with the clinician looking for major developmental issues, while also estimating the fetus’s gestational age. During the first trimester, the ultrasound is the most accurate way to confirm the age, by measuring the fetus’s crown-to-rump length. The predictions are generally accurate to within five days of the expected due date. The second scan is usually performed between 18-22 weeks, and is used to identify the number of fetuses, the placental location, the amount of amniotic fluid present and to help estimate fetal weight and size. It can also identify the fetal position, heart rate, presence of movement and breathing.
Limited fetal ultrasound: A limited fetal ultrasound is performed to help the clinician answer a question, like confirming the fetal heartbeat or checking fetal positioning. An optional nuchal translucency (NT) ultrasound would be done around 10-13 weeks, to measure the fluid-filled space behind the fetus’s neck. An abnormal measurement could indicate chromosomal issues like Down syndrome, and the clinician may also order a blood test to measure hormones and proteins. A clinician may recommend limited ultrasounds for other medical concerns, such as hypertension, maternal diabetes, bleeding, low amniotic fluid or advanced maternal age.
Specialized fetal ultrasound:Specialized fetal ultrasound examinations may be recommended if the clinician wants to monitor something like fetal growth. This exam may use a special ultrasound technique like 3-D ultrasound or Doppler ultrasound.
Types of fetal ultrasounds
While ultrasound in general involves using sound waves to create a picture of what is inside the body, there are different techniques.
Transabdominal ultrasound: A transabdominal ultrasound is the traditional version those who are pregnant may envision. The patient lies on their back and the technician moves a transducer over the abdomen after applying a thick gel. This technique works best when the patient drinks water before the exam, as a full bladder makes the sound waves travel better.
Transvaginal ultrasound: While the sound waves work the same way, the transducer is a wand inserted into the vagina. The patient does not need a full bladder for this exam—an empty or partially full bladder is fine.
Doppler ultrasound: While a standard ultrasound shows pictures, a Doppler shows blood flow. Doppler ultrasound is used to hear the fetal heartbeat and see how well the blood is circulating through the vessels or umbilical cord. It may be used for patients who have complications like diabetes, high blood pressure, heart or kidney problems, placental development issues or potential fetal growth issues. It’s more typically done during the third trimester.
Guiding ultrasound: Ultrasound may be used to guide procedures, like chorionic villus sampling (CVS) and amniocentesis, when a needle is inserted into the womb to biopsy the placental tissue or the amniotic fluid. These tests look for abnormalities. The ultrasound ensures that the needle is in the right location.
3-D ultrasound: This more advanced ultrasound takes thousands of pictures at a time, producing a photo-quality image. It may be used to monitor the baby’s organ development, and to look for potential facial abnormalities. It can also be used to visualize problems with the uterus.
4-D ultrasound: 4-D ultrasound is similar to 3-D ultrasound but it is a video. It shows the baby’s movement. It may also show potential fetal abnormalities. Both 3-D and 4-D ultrasounds are sometimes referred to as “keepsake ultrasounds,” as they provide more realistic views of the baby and people like to frame or share the images. Medical associations and government health organizations do not recommend getting these ultrasounds unless there is a medical necessity.
Ultrasound safety and image sharing
These same associations and organizations recommend only getting an ultrasound performed if there is a valid medical reason. Ultrasounds should only be performed by licensed medical practitioners for the proper indications.
Ultrasound is not able to identify every fetal risk or find every anomaly, but it can be helpful. If a pregnant patient experiences complications when away from the doctor or medical system, having access to the ultrasound exams and reports allows them to share the records to help the consulting physician get more information.
Accessing your Ultrasound Imaging
With PocketHealth, you can share your pregnancy ultrasounds with healthcare providers, family and friends. PocketHealth is a patient-centered image-sharing platform providing easy and fast access to patients, designated providers and anyone you wish to share them with. These medical imaging records can be accessed anytime and from anywhere, giving you digital access to the full-resolution ultrasound images forever. This is helpful whether you want to revisit your own images, if you are seeing multiple doctors or traveling outside the area. PocketHealth makes it easy to maintain access to your imaging records.