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More than determining the baby’s sex, ultrasound is carried out for a number of medical reasons. An ultrasound scan or sonogram is a safe procedure performed by sonographers or midwives trained to do the exam. Using sound waves, real-time images of the babyinside the womb can be seen. It is a part of prenatal care to gather information about the mother and her baby’s health. Learn more about the most important reasons why obstetric ultrasonography or ultrasound is a routine exam throughout pregnancy.

Early Stage

During the early stage of pregnancy, ultrasound is used to first confirm pregnancy, check if the embryo is developing inside the womb or inside a fallopian tube, confirm fetal number and calculate gestational age to estimate due date. Transvaginal ultrasound is used in this stage. It uses a transducer, a small probe inserted into the woman’s vagina to capture images. As early as 5 weeks, transvaginal ultrasound can already be performed because the gestational sac can be seen. By the time the sac measures 20mm, the embryo should show up. The heartbeat appears by the time the embryo measures 5mm to 7mm, which is about 7 weeks of pregnancy.

First Trimester

Standard ultrasound scans during the first trimester aim to determine the size, number and location of the gestational sac. It identifies the embryo and yolk sac, measures the crown-rump length, confirms fetal number, checks cardiac activity, assesses embryonic anatomy, evaluates the uterus, ovaries, tubes and other parts of the reproductive system.

Second Trimester

The middle part of pregnancy is exciting for most moms since they are halfway there. At this stage, detailed ultrasound can take place between 18 to 20 weeks to have a good look at the baby. The doctor or trained technician will carry out the transabdominal scan by applying some gel onto the mother’s abdomen and gliding a transducer across it to perform the ultrasound.

During this stage, the baby’s heart rate is checked, as well as the vital parts of the body (brain, heart, liver and kidneys). The doctor will identify any birth defects, measure the level of amniotic fluid, examine the placenta, and sometimes determine the baby’s sex. Newer technology offers 3D or 4D scans for a better look at the nose and body structure.

Third Trimester

The last ultrasound can happen at 20 weeks or after. If it’s past the due date, the doctor keeps a close watch on the baby’s heart rate, the placenta and amniotic fluid levels. Follow up scans are also done to scan if the placenta has moved away from the cervix because the doctor may have to recommend caesarean section delivery if not.

Prenatal ultrasound is safe for both moms and babies especially when done by reputable ultrasound facilities. Apart from medical scans ordered by doctors to detect developmental abnormalities, there are elective ultrasound scans you can choose to undergo yourself to have high quality imaging as keepsake. Private companies such as can provide you with such services for an affordable fee.

Image via phaendin

About The Author

Sneha Srimani is a Bachelor of Science graduate in health education. She is also social media manager at Before coming to Nucleus Accumbens, she worked as a Jr. Medical Physicist. Now she decided to share her experience and medical information through this blog.