Womb with a view – Everything you should know about an ultrasound during pregnancy!

What is an ultrasound?

An ultrasound helps you get a look into your womb to see the proper position, growth, and movement of the little one. It is generally done in 2D, but nowadays, even 3D or 4D scans are quite in vogue as they offer a life-like image of the growing fetus.

Is an ultrasound harmful to the baby?

An ultrasound sends high-frequency sound waves through the growing belly into the uterus of the soon-to-be mother. It has been used for more than 4 decades so far and is not known to cause any harm to the mother or child. That being said, an ultrasound should be used only when absolutely required. Also, unlike an X-ray, this is safe as it does not pose a threat to the baby by exposing it to harmful radiation.

What can be seen on an ultrasound?

Your baby’s structures are seen from black and white to all the shades of grey in between (not the “50 shades of grey” kind!).

Hard tissues:

Which is mainly bones, is seen as white.

Fluid/Empty space:

Such as the amniotic fluid (in which the baby lies) is black.

Soft tissues:

Such as muscles, skin, organs etc have varying shades of grey.

How many scans would you require during pregnancy?

This is purely dependent on what your gynecologist deems right and varies from one expectant mother to another.  Generally, around 4 to 5 scans are taken during the course of a low-risk pregnancy.

More scans are taken if :
  1. The expectant mother’s age is > 35 years.
  2. There is more than one baby in the womb (twins, triplets or more).
  3. If there is any medical condition that may cause a complication in the future, like an aging placenta, a cyst or a tumor etc.

How are the scans taken?

An ultrasound is performed either:

1.Transvaginal scan (TVS):
  • Done before 10 weeks of pregnancy.
  • A probe is introduced vaginally.
  • You need to empty your bladder (to prevent obstructing your baby’s view) and undress from the waist down.
  • Gives a clear image in the early stages of pregnancy.
2. Abdominal scan:
  • Done after 10 weeks of pregnancy.
  • A hand-held probe is moved over your abdomen after placing some cold gel.
  • You need to have your bladder full (to push your uterus higher, giving you a better view of the baby) and expose your tummy.
  • Gives a clear image in the early stages of pregnancy.

Does an ultrasound hurt?

While doing an abdominal scan, you may feel a tingling sensation (due to the cold gel) and a bit of discomfort while doing a trans-vaginal scan ( the less anxious you are about it the better). Apart from a little minor inconvenience, you feel nothing.

So, what can be assessed in an ultrasound?

In the first trimester:
  1. The position of the baby (right or not).
  2. Baby’s heartbeat (starts at 6 weeks).
  3. Confirm your conception date and predict your due date.
  4. Gestational age of the baby (by measuring the Crown-Rump Length (CRL) from week 7 onwards).
In the Second trimester: Anomaly Scan
  1. The position of the baby (right or not).
  2. Baby’s growth and development (size, shape, and weight along with the development of vital organs).
  3. Amniotic Fluid Index (AFI).
  4. The position of the placenta.
  5. Evidence of any congenital/chromosomal abnormalities (like spina bifida,  heart problems etc).
  6. Measurements of the baby:
  • Head diameter (biparietal diameter or BPD)
  • Head circumference (HC)
  • Femur or thigh bone length  (FL) 
  • Abdominal circumference (AC)
In the Third trimester:
  1. Movements of the baby.
  2. Position of the placenta (if it is too close to the cervix, the condition is known as placenta praevia and indicates the need for a C-section).
  3. Amniotic Fluid Index (AFI).
  4. Measurements of the baby (in particular the abdominal and head circumference).
  5. To check if the baby is in breech position ( indicates the need for a C-section).


During the trimesters, an ultrasound helps the doctor know if the fetus is growing normally and reaching the desired milestones. We at Savika advise you track the development along with us, thus making this journey a memorable one for us too.










Dr. Aishwarya Rajeev has completed her MDS degree and is currently pursuing her PhD. She is an avid reader and loves to teach and write!

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