Ultrasound scans are used to help assess the progress of your pregnancy and to identify whether there are any possible problems with your baby.

Scans are performed in a hospital or clinic by a Sonographer trained in ultrasound and your results are given right away.  

Here, Julia Hindle Lead Sonographer at Baby Premier Medical Ultrasound and Maternity Services answers some common questions about ultrasound.

What is an Ultrasound scan?

An ultrasound scan is a screening test that not only allows you to ‘see’ your baby but also helps assess the progress of your pregnancy and detect possible abnormalities and problems. It works by creating images from high frequency sound waves, which are directed into the body then reflected back to a scanner that measures them.

What happens during a scan?

You will be asked to lie down on an examination table and some special gel will be spread over your skin to enable the scan to define your baby. An ultrasound scanner/transducer (which resembles a small paint roller) is then rolled back and forth over your stomach to send sound waves through the skin and muscles. These waves are then turned into an image that appears on a screen in front of you and the Sonographer.

Does a scan hurt?

An abdominal scan is completely painless though it may feel uncomfortable when the ultrasound scanner presses down, especially if you have a full bladder or it’s later in your pregnancy.

Are ultrasound scans safe?

Ultrasound scans have been used for over three decades with no known abnormalities associated with them. People worry about the safety of scans because scans come under the umbrella of Radiology and so they are often mistakenly associated with X-rays and CT scans, which carry a risk of radiation. Ultrasounds scans work via sound waves, and have no radiation risk at all.

How many scans will I be offered?

Pregnant women will normally be offered two scans on the NHS; a dating scan at 12 weeks pregnant, and a detailed anomaly scan at 20 weeks pregnant to check for physical abnormalities. You’re unlikely to have another scan unless your midwife is concerned about your baby’s growth or position, or you decide to opt for a private one.

What will the scan detect?

Ultrasounds can provide accurate information on the number of babies you are carrying, the way that your baby is developing and they can also detect some birth defects such as Spina Bifida. However, many other problems, including all chromosomal and genetic abnormalities, cannot be diagnosed with a scan though the scan may give clues about your indication of risk.

What are the benefits of a dating scan?

Your dating scan will give your midwife and doctor a more accurate estimation of your baby’s due date than calculations based on the date of your last menstrual period. This is important, as it will reduce the likelihood of your pregnancy being induced for a prolonged pregnancy (a pregnancy that goes beyond 40 weeks). Reliable dating is also important if you choose to have a screening test for Down’s syndrome because results are time dependent.

What are the benefits of a 20-week anomaly scan?

Many problems cannot be identified until later in your pregnancy, which is why a scan around 20 weeks of pregnancy is so important. At this scan a thorough examination of your baby’s anatomy is taken to check that your baby is developing, as he/she should be. Measurements of your baby’s head, thigh bones and abdomen are taken and also images of the spine, heart, stomach, kidneys, bladder, abdomen, and limbs, hands and feet. This scan also checks the position of the placenta and assesses the volume of amniotic fluid that is around your baby.

Will this scan reveal the sex of my baby?

Though many parents do find out the sex of their baby during their 20-week scan it really depends on your baby’s position. Many hospitals now have a policy of not saying what the sex of the baby is, as they can’t be 100% certain.

Can I refuse to have a scan?

Any woman can refuse to have an ultrasound scan and some do because they don’t want to know if there is anything wrong with the baby before it’s born. However, it’s worth bearing in mind that a scan can detect things that could be treated in vitro such as problems with twins or problems with the lungs, as well as prepare you for potential problems that may need to be faced. However, no one can force you to have a scan. The decision is entirely up to you.

What’s a 4D scan?

A 4D scan is an ultrasound examination that allows you to see the face and features of your unborn baby moving in 3 dimensions and in colour. The 4th dimension is time, so you actually see your baby moving, waving its arms, yawning, smiling, and sucking its thumb. 4D scans are thought to promote bonding but are not available on the NHS and can only be done privately, usually at around 26 -32 weeks pregnancy.