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OB/GYN – The Ultrasound Tech’s Role in Pregnancy

For parents expecting a child, one of the most exciting moments during pregnancy is that first, prenatal ultrasound. It can also be a scary time for mothers that have higher-risk pregnancies. Ultrasound technicians who are specialized in OB/GYN typically would perform sonograms on fetuses growing inside their mother’s womb.

Ultrasound technician with patient

Since both fields deal with the same region of the female body, often sonographers will perform ultrasounds for both health areas. The ARDMS (American Registry for Diagnostic Medical Sonography) offers joint certification in both specialties and many ultrasound schools offer courses or concentrations that combine the two fields.

Obstetrical ultrasounds are performed for many reasons including confirming pregnancy and assisting with determining the date of conception. Sonograms may also be used to detect multiple births (i.e. twins) and even ectopic pregnancies (abnormal pregnancies where the fetus is developing outside the womb). Obstetric sonographers may perform ultrasounds on pregnant women to detect abnormalities or signs of congenital diseases, particularly if the female is high risk due to age or medical history.

For smooth pregnancies, ultrasound technicians are there to monitor the growth and development of the fetus until birth. For women who are not at risk, typically they will go in for an ultrasound once during the first trimester and again at the 18th to 20th week stage, according to the Oregon Health & Science University’s Center for Women’s Health. Women who are at higher risk will go in for more ultrasounds.

Pregnancy Ultrasound Week by Week

First Trimester (Week 1 – Week 12)
According to the American Pregnancy Association, several aspects or criteria may be assessed during a first trimester ultrasound. These include confirming that the pregnancy is viable and measuring the crown-rump length of the baby to determine his or her gestational age.

During the first trimester, a sonographer can also confirm that there is a heartbeat and determine if the pregnancy is ectopic or molar (when a non-viable egg is fertilized). Transvaginal ultrasounds may be performed (where the probe is inserted into the vagina rather than being passed over the abdomen) to detect ectopic or molar pregnancies.

Second Trimester (Week 13 – Week 26)
The most standard ultrasound for women who are not at risk takes place during the second trimester, halfway through the pregnancy, between the 18th to 20th week. At this stage, sonographers can detect the gender of the fetus. This mid-pregnancy ultrasound serves to evaluate the health and development of the fetus. At this stage, the ultrasound technician can confirm if there is more than one fetus growing inside the mother’s uterus (multiple births).

Abnormalities and signs of diseases may also be detected at this stage such as the presence of congenital defects, the incorrect amount of amniotic fluid or miscarriages (which usually happen during the first three months of pregnancy) and stillbirths (which occur after week 20). Signs of Down syndrome may be detected between the 13th and 14th week, according to the American Pregnancy Association.

Third Trimester (Week 27 – Birth)

Sonographer with pregnant Mom

Women who are at a higher risk, such as those who had problems with previous pregnancies, or women who are carrying multiple babies will most likely go in for an ultrasound during the third trimester.

Aside from monitoring fetal development and health, one purpose for an ultrasound at this stage is to determine if the placenta is located too close to the cervix (placenta previa) which may warrant a caesarian section for the birthing process.

A third trimester ultrasound will also be ordered if the OB/GYN suspects the fetus is in a breech position (where the baby’s head is farthest away from the cervix), which also may call for a caesarian section.

The ultrasound technician’s role is essential throughout an entire pregnancy. If you would like to work in this field of sonography, you can complete an ultrasound degree and complete courses and clinical rotations related to obstetrics or the joint OB/GYN field.

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