Pregnancy ultrasound: 11 things pregnant women need to know during pregnancy

Written by Master, Dr. Nguyen Ngoc Tu, Obstetrician and Gynecologist, Department of Fetal Medicine, Obstetrics and Gynecology Center – Share99 Times City International Health Hub

Fetal ultrasound uses ultrasound waves to erect images and observe the structure and functioning of the fetus in the uterus. During the ultrasound, the doctor will use an ultrasound probe placed on the pregnant woman's abdomen (abdominal ultrasound) or use an ultrasound probe wrapped by a condom to insert into the pregnant vagina (vaginal probe ultrasound) to conduct an ultrasound.

1. How is pregnancy ultrasound performed?

Ultrasound is performed in the low light room to ensure the image displayed on the machine is best. You will be lying in an ultrasound bed, exposing the abdominal area where an ultrasound is required (abdominal ultrasound) or revealing the closed area(vaginal probe line ultrasound)

The doctor will apply a little gel to the area where the ultrasound is needed to ensure the best sound wave conduction. Fetal image displayed on the screen in black and white

ultrasound screening for fetal malformations

Pregnancy ultrasound is painless and helps pregnant mothers see fetal images

2. What should pregnant women prepare before an ultrasound?

Ultrasound is best performed when the bladder is not full of urine (except in cases of abdominal ultrasound in early pregnancy). Therefore, it is necessary to urinate before ultrasound. Do not apply body lotion/balm within 48 hours before ultrasound.

Ultrasound does not cause pain. However, in some cases, the doctor presses the probe slightly strongly can cause discomfort.

In detail about the development of the fetus week by week, every parent should find out:

3. Is pregnancy ultrasound safe?

Ultrasound has been used in obstetrics for decades and is considered safe for pregnancy, and there is already a complete set of process guidelines and standards. Following that standard, until now, no one has recorded an ultrasound that harms the pregnancy

There is no effect on miscarriage or affecting the fetus when using a vaginal probe,even when vaginal bleeding occurs.

4. When is an ultrasound performed?

Ultrasound can be performed at any time during pregnancy. Depending on the specific case, the doctor can specify the time and number of ultrasounds for each person differently, there are 3 times of ultrasound in pregnancy that experts recommend are really necessary:

  • From 12 weeks to 13 weeks 6 days
  • From 19 weeks to 22 weeks
  • From 30 weeks to 32 weeks

5. How long does a pregnancy ultrasound last?

Ultrasound screening for fetal malformations is usually about 15-30 minutes. In some cases when pregnancy is difficult to assess due to difficult positioning or excessive movement, or thick layers of abdominal wall tissue hindering, making it harder for ultrasound waves to pass through, the ultrasound time may have to last longer or make an appointment to the next time.

6. Why does a pregnant woman need an ultrasound early in pregnancy?

  • Evaluation of intra-uterus or extra-intra-uterus pregnancy
  • Assess if there is a pregnant heart
  • Evaluation of the number of pregnancies
  • Expected birth
  • Evaluation of uterus abnormalities and appendixes
  • Ultrasound assesses the cause of vaginal bleeding

7. What does an ultrasound of 12 weeks to 13 weeks 6 days include?

Assess the gestational age and expected birth by the length of the buttocks (which is the most accurate time of evaluation).

Screening for risk of chroma abnormalities:

  • Measurement of the translucent distance at the back of the neck (NT). The translucent area at the back of the neck is the layer of transal skin in the back of the neck of the pregnancy. All pregnancies have this layer of epidemic, but many pregnancies with NST abnormalities show signs of increasing the thickness of this epidemic layer.
  • NT measurements combined with Double test blood tests can screen about 90% of fetal cases with Down syndrome.

Early observation of anatomy structures such as hands, legs, abdominal wall, heart, skull, vegetable cake … to detect major pregnancy abnormalities

Evaluation of blurred vision in the brain (IT) to be able to detect early neurological malformations.

Pre-production risk screening

8. What does a 19-week to 22-week fetal erthal ultrasound consist of?

  • It is the best period of pregnancy to assess abnormalities in the structure of the pregnancy. 19 weeks is the time when a detailed assessment of the gestational structure can be started, and 22 weeks is the best time to evaluate.
  • Observe the urethorization and structure of the skull and brain, face, digestive system such as liver, intestines, respiratory system such as lungs, diaphragm, retinal system such as cardiovascular, urinary system such as kidneys, bladder, bone system and veins, sex …
  • Observe vegetable cakes, umbilical cords and amniotic fluid
  • Measurement of cervical length to assess the risk of premature calving
  • Assess your baby's development by measuring their biological indicators such as dipolar diameter, head ring, femur length, abdominal ring … to assess whether the baby develops corresponding to gestational age, whether it is small, and if it is small, there are risks.

Pregnancy ultrasound

Fetal ultrasound assesses the state of health as well as fetal malformations

9. What does a 30-week to 32-week pregnancy ultrasound include?

It is an important time to assess the growth of thai.

Just like the time of 22 weeks, the doctor will measure the biological indicators of the pregnancy to assess if the fetus is developing normally, or the pregnancy is small or larger than normal

Fetal weight will be manifested in the report according to the cypress

  • Cypress sugar from 10 to 90 is a normal weight pregnancy
  • The cypress line below 10 is a small pregnancy
  • Cypress sugar per 90 is a large pregnancy

Weight on ultrasound has a deviation from the actual about 10%

Doppler ultrasound is used to assess the pregnancy's veins through the main arteries. Thereby assessing the risk of oxygen deficiency, impaired vegetable cake function of pregnancy

With a small pregnancy will be able to have an uns good reacception for the pregnancy. In order to be able to have a firm diagnosis as well as give the best treatment, the doctor can prescribe additional ultrasound and monitor the growth rate of the pregnancy through ultrasounds.

With large pregnancies, often pregnancies older than gestational age are born healthy. However, a small number of large pregnancies are caused by mation's conversion disorders such as gestational diabetes mellitus, which if not detected can cause dangerous complications for both mother and child. To be safe for pregnancy, your doctor will require additional tests.

Evaluate the structure of the organs of the pregnancy like week 22 and add some differences such as assessing late-appearing lesions such as cortex damage, intestinal obstruction, narrowing of the renal-ureteral tank, Zika infection, CMV, Rubella …

10. Can ultrasound detect all fetal abnormalities?

Depending on the pathology, there are more easily detectable pathology, there are diseases depending on the degree of manifestation, progressive changes, difficulty detecting even un detectable on ultrasound.

  • Some abnormalities such as heart abnormalities or intestinal obstruction… can usually only be detected at a late stage of pregnancy.
  • Ultrasound screening for fetal malformations can rule out the majority of the above-mentioned malformations but cannot exclude all fetal abnormalities.
  • Diseases such as autism, cerebral palsy, intellectual retretness cannot be detected on ultrasound because these diseases are not brought about by structural abnormalities.

11. If the ultrasound results have pregnancy problems what will have to do?

It would be very natural if you were worried when the results of a pregnancy ultrasound showed there was a problem with your pregnancy. However, problems on ultrasound can range from large, obvious, serious abnormalities to minor problems, just a form of structural variations that have no consequences. Therefore, when the ultrasound is suspected to be problematic, you will be transferred to a specialist in fetal medicine for advice and guidance on diagnosis and handling in detail.

Fetal abnormalities, treatable, may not, there are types that can be treated right from the fetal stage, some have to wait until birth to be able to treat. Depending on the abnormality, you will be guided and consulted step by step: what to pay attention to follow in pregnancy, plan your birth for you, plan post-birth care for your baby, make a plan for surgery if necessary, guide the care of the baby after being discharged from the hospital … Regardless of the type, this is also the time when you need the most support, not just medically.

The first 3 months are the most sensitive time during pregnancy. In order for the mother and baby to be healthy, parents should note:

  • Understand early signs of pregnancy, pregnancy poisoning, bleeding during pregnancy.
  • The first pregnancy examination is timely, correct and sufficient, avoiding the examination too early / too late.
  • Screening for fetal malformations at the 12th week detects dangerous fetal malformations that can intervene early.
  • Distinguishes the usual vaginal bleeding and pathology vaginal bleeding for timely pregnancy retention intervention.
  • Screening for thyroid disease in the first 3 months of pregnancy avoids dangerous risks before and during childbirth.

Share99 currently has many maternity packages (12-27-36 weeks), of which the 12-week package maternity program helps monitor the health of mothers and babies at the beginning of pregnancy, early detection and timely intervention of health problems. In addition to the usual services, the 12-week maternity monitoring program has special services that other maternity packages do not have such as: Double Test or Triple Test for Fetal Malformations; dosing tests of neovascular factors for pre-seizure diagnosis; thyroid screening tests; Rubella test; testing for parasites transmitted from mother to child seriously affects the brain and physical development of the baby after birth.

For direct advice, please click hotline number or register online HERE. In addition, you can register for remote consultation HERE


  • 22 weeks: Best time to survey fetal malformations
  • Does a probe ultrasound affect the fetus?
  • When is an ultrasound of the vaginal probe required?

About: Minh Quynh

b1ffdb54307529964874ff53a5c5de33?s=90&d=identicon&r=gI am the author of I had been working in Vinmec International General Hospital for over 10 years. I dedicate my passion on every post in this site.


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