Ultrasound Scans and How to Read Them

One of the most exciting parts of pregnancy is getting that first ultrasound, and then all the subsequent ultrasounds because they help you visually track the growth of your baby in utero, which is always something you expect to be unable to do at first. Reading an ultrasound, however, can be tricky at times. While it is a type of imaging, it’s not quite the same as taking a picture, so it may take a while to get accustomed to it. Once you know how to read it, you’ll be able to understand most of all the tiny features that you see.

How does one read an ultrasound?

How ultrasound works is that it creates shadows of the objects inside the body coinciding with where the ultrasound probe was in contact with your body. If you look at the image straight, at the top edge is where the probe was, and everything below it is what is under your skin/inside your body, underneath the probe.

Ultrasounds, in a loose classification, can be divided into two parts – the details, and the graphics.

The part surrounding the actual image contains some numbers and letters. These are basically for the doctors to read and understand and contain information that is required for the hospital administration. It includes details like your patient ID, your doctor’s name, the date and time at which the ultrasound was taken, etc. These are the details of the ultrasound. This isn’t quite relevant to you, however. What you want to pay more attention to is the area in the entire inner part of the scan.

Initially, the inner/middle portion of the ultrasound appears to be just patches of colours in shades of black/white/grey. This is what you’re going to need to and want to focus on. In order to understand the picture, you need to remember what these colours mean. Any area that is white in the scan indicates the presence of a solid in that area of the body (in the case, your womb); Grey areas indicate (fluid filled) tissues; Black areas indicate fluid-filled cavities. These are the graphics of the ultrasound.

Now that you know what all the colours mean, let’s talk about the image that you see. The womb is generally outlined in grey lines and just inside will be a black space which is an indicator of your amniotic fluid. In the middle of this black space, you’ll see a mass that consists of a mix of grey, black, and white. You’ll be able to make out the outline of your baby and his/her features such as the head and hands. If you see clear white areas, those are where your baby’s bones and solid tissues are, so you’re looking at your baby’s skeleton and organs.

As the weeks progress, you’ll be able to make out more features; while at 2-3 months, you may just be able to make out the outline of the body, at 5-6 months, you may be able to make out as much as the fingers and spine. At around 18-20 weeks is when you can determine the sex of your baby by reading the ultrasound scan.

There are certain abnormalities that can also be identified in ultrasounds. If the particular area that is being examined in the scan is brighter or whiter that it’s supposed to be, it is known as an enhancement. It could mean that there is excess liquid or a cyst present in this region. If a particular region is darker than it’s supposed to be, it could be caused due to shadows and this is known as attenuation. Anisotropy is when certain areas are highlighted or darkened due to the angle of the probe, and not because of the features of the structure itself.

Nowadays, there are also 3D and 4D ultrasound options available. While ordinary ultrasounds show a two-dimensional image of the fetus, a 3D ultrasound is capable of depicting a three-dimensional image which makes identification of features much easier. A 4D ultrasound is a type of ultrasound imaging in which a video of the fetus is captured, using the same technology as 3D ultrasounds. The first ultrasound is generally done at around the 10th week of pregnancy. 

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