Ultrasounds in Pregnancy

There are 2 main ultrasounds which you may have during your pregnancy. Both are used to see how your baby is growing and developing, and to check the female pelvic organs during pregnancy.

Transvaginal  (Also known as TV or internal)
This is done by inserting a probe into the woman’s vagina. You will usually have a empty / partially full bladder, be asked to strip from the waist down, and lie with your legs flat on to the bed. The sonographer will place a condom and water based gel onto the end of the probe, and insert it into the vagina. The scan feels a little uncomfortable, but there should not be any pain. The probe works by transmitting sound waves which bounce off the structure of the womb and the baby, producing an image of the baby. There are no reported risks of having a scan of this type. The scan will usually last around 5-10 mins.

Pregnant women normally have this type of scan before 12 weeks, when it is too early for an abdominal scan to pick up the baby’s image clearly. It will be given if they are having unusual pains, bleeding or have had complications in previous pregnancies, and this type of scan will also used at around 26-28 weeks to check the length of your cervix and check the placenta is working correctly and that you are not showing any pre signs of pre-eclampsia.

Reasons to have a transvaginal ultrasound in the 1st trimester:

  • Unusual bleeding or pain – to evaluate the risk of miscarriage or eptopic pregnancy
  • To look at the baby’s heartbeat and at the placenta
  • To check foetal growth
  • To look for a potential cause of any bleeding
  • To check if the cervix is opening (See incompetent cervix
  • If you are at high risk of complications in pregnancy

Most pregnant women in the UK are offered at least two abdominal scans during pregnancy, unless there is a reason to do more. The first is usually between 11 and 14 weeks, and the other is offered between 18 and 22 weeks. Again, there are no reported risk factors to having these scans. Usually you are offered a change to purchase a scan image after the scan (some are offered free), but this is not offered at every hospital and charges vary.

Dating Scan
The first scan is usually done with a full bladder: the baby is still small so this pushes your uterus up and makes the image much clearer.  A cold gel will be placed on your tummy (lower part near the top of the groin) and a small scanner will be rubbed over your tummy until the baby’s image is shown on screen. There may be some mild discomfort, due to having a full bladder, or if the sonographer needs to put pressure on in order to get a clear picture.

Scans in the first trimester are done to:

  • Confirm pregnancy
  • Give you a approximate age for your baby, often you may find that dates don’t add up, but the age given during the scans will give you a more accurate due date / estimated due date)
  • Pick up any problems such as eptopic pregnancy or miscarriage
  • Check the babies heart rate
  • To confirm / check for multiple pregnancy
  • To check the placenta, cervix, uterus and ovaries.

Anomoly Scan
The second scan  is often done without a full bladder, as your baby is bigger now. It is done much the same as the 1st scan, but may take a bit longer, as measurements need to be checked to make sure your baby is growing correctly, and that there are no concerns with the babies development, fluid or placenta.

Scans in the second trimester are done to:

  • Confirm the estimated due date based on the babies growth and development
  • Check the baby’s growth and make sure there are no issues with the baby’s organs
  • Check the position of the baby
  • Look at the gender of the baby (Some hospitals do not offer this and is up to each hospital individually if they are offering this service)
  • To check for multiple pregnancy / to check a multiple pregnancy is progressing correctly
  • To check the placenta placement and make sure it is working correctly
  • To make sure there is the right amount of fluid around the baby
  • To check the mother’s pelvis

There may be a need to return later on if your baby is in a unusual position or they are unable to complete all the measurements, there is nothing to be concerned about and is a common thing in pregnancy. Usually a cold drink or some chocolate or a walk around the grounds, is enough to get your baby to change position. You may also have more scans in higher risk pregnancies, multiple pregnancies, or where a problem with the placenta is detected.

3D/4D Ultrasound
3D/4D Ultrasounds are not part of routine antenatal care in the UK, but may be something you consider paying for yourself in a private clinic. 3D scans work the same way as standard 2D ones but instead of the sound waves are sent at different angles and are processed by a sophisticated computer program which creates a 3D volume image of the baby. When the scan is shown in real-time, it is referred to as a 4D scan, with the fourth dimension being movement.

by Michelle, mum to Joshua, Alexa and Nathan

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