Understanding Prenatal Ultrasounds
Ultrasounds are an important prenatal screening tool. With an overwhelming amount of information for new mothers to retain, some may not be familiar with the various ultrasound techniques or the standard ultrasound schedule.
What Are the Ultrasound Techniques Used for Prenatal Screening?
The following options may be recommended by your doctor:
- Traditional ultrasound - this exam is conducted externally and it produces 2-D images using a transducer on the maternal abdomen. This method is used primarily in the 2nd or 3rd trimester of your pregnancy, generally after 12 weeks gestation. A more advanced, detailed scan (Level II ultrasound) can also be used to look at a specific problem.
- Transvaginal ultrasound - this is an exam where the transducer is used in the vagina during the 1st trimester to create images of a fetus' early development.
- Doppler ultrasound - this type of ultrasound relies upon frequency waves as they bounce off of moving objects like blood cells. This is used to assess placental function and fetal well-being.
- 3D Ultrasounds and Dynamic Ultrasounds - 3D ultrasounds can provide a better look at a developing fetus. 4D and Dynamic ultrasounds look at the motion of a fetus and the facial movements before it is delivered.
An expectant mother's Obstetrician will determine the appropriate ultrasound options, as well as the ultrasound schedule.
When Are Ultrasounds Typically Performed on Expectant Mothers?
The ultrasound schedule can vary as there is no required protocol. At Women's HealthFirst, 3 ultrasounds are performed during an uncomplicated, full-term pregnancy. At your first prenatal visit, an ultrasound will be performed to document a fetal heartbeat and to assign a final EDC, or a due date. At 20 weeks gestation, a fetal survey ultrasound is done to assess all fetal parts and to screen for any developmental abnormalities. Finally, at 36 weeks, a growth ultrasound is done to assess current fetal size, its projected weight at delivery, and to help guide your physician during labor for a safe delivery of your baby. Other scans are performed, as needed, if the pregnancy becomes complicated by maternal or fetal problems.
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