Ultrasounds have become very much an ingrained part of the pregnancy experience.
Prior to the 1970s, ultrasound wasn’t a routine practice in maternity care.
Today, depending on the type of maternity care you choose and the country in which you are giving birth, you might have more than two ultrasound scans.
What Can I Expect At My First Trimester Pregnancy Ultrasound?
First trimester ultrasounds are optional and you might decide having one isn’t necessary.
It can be an exciting and stressful time when you have your first ultrasound. You are looking forward to seeing your baby on the screen but anxious and unsure of what to expect.
This article covers what you is likely to happen at your first trimester pregnancy ultrasound.
How Is The First Trimester Ultrasound Performed?
For most women, a transabdominal ultrasound is used after eight weeks gestation.
Depending on where you live, your care provider might do the scan, at your local hospital; you might need a referral to a sonography clinic.
Ultrasounds are usually performed by moving a transducer wand over your belly. The technician will ask you to lie on your back and will then rub a gel onto your skin. This helps the transducer wand to glide easily over your belly and improves the transmission of sound waves.
The sounds waves bounce off the surfaces inside your body, including your baby, and produce the images you will see on the screen.
In early pregnancy, when the developing embryo is very small, a transvaginal ultrasound might be needed to get a better look at the baby.
Transvaginal ultrasound is an internal ultrasound. It is in the form of a long, thin wand, about 2cm in diameter. It is covered with a disposable sheath (similar to a condom), then coated with a small amount of sterile lubricant gel. The transducer wand is then gently inserted into the vagina.
You will have a choice as to whether or not a transvaginal ultrasound is performed. If you have concerns about this type of scan, discuss them with the technician.
Do I Need To Undress For A First Trimester Ultrasound?
If you’re having a transabdominal ultrasound, you need to make sure the technician has access to your belly. You might choose to wear a top which can be pulled up and bottoms that can be pulled down easily.
Otherwise, you will be provided with a gown to wear. Your privacy should be respected at all times and you should have a screen to go behind while you change.
If you require a transvaginal ultrasound you will need to remove your lower clothes. A towel will cover your lower body and a gown will be provided if necessary.
Do I Need To Have A Full Bladder?
Usually the technician will be able to get a better image during a transabdominal ultrasound if your bladder is partially filled.
When the bladder is full, it helps move the bowel out of the pelvis and into the abdomen. This gives the technician a better view of the uterus.
At the time of your booking, you should be instructed what to do with regard to fluid intake before your ultrasound.
Generally the advice is to empty your bladder one hour before your appointment, then drink two glasses of water and avoid emptying your bladder until after the ultrasound.
Your bladder shouldn’t be so full that it’s painful. If you become uncomfortable to the point of pain, you should empty a small amount.
If you have a transvaginal ultrasound, you won’t need to have a filled bladder.
Why Do I Need A First Trimester Ultrasound?
Not all women need to have an ultrasound in the first trimester of pregnancy. Your care provider might suggest an ultrasound for a number of reasons:
- To confirm the pregnancy. You might have had vaginal bleeding or be worried about miscarriage due to previous loss. This ultrasound can usually detect a heartbeat at 6-7 weeks
- To estimate a due date. You might be unsure of date of conception or the date of your last menstrual period, or you might have irregular cycles. Estimated due dates are used to assess your baby’s growth and wellbeing.
- To confirm the location of your pregnancy. Your care provider might have concerns the pregnancy is located within the Fallopian tube (ectopic pregnancy).
- To identify pregnancies at risk of miscarriage. The ultrasound can detect changes such as small or irregular sac, or slow heart rate, which indicate an increased risk of miscarriage.
- To confirm the number of babies. Your care provider might believe you have more than one baby present, particularly if your pregnancy was conceived via IVF, if you have severe early morning sickness, or if your uterus is bigger than expected for gestation.
- To investigate any abdominal or vaginal bleeding, and check for potential problems with the pregnancy or your own health
- To check your pelvic organs, if you have a history of fibroids or ovarian cysts.
What Is Checked At A First Trimester Ultrasound?
Each ultrasound will depend on the individual woman, her personal health history, and any previous pregnancies and ultrasounds.
The technician will do the following checks, possibly focusing more on some than on others:
- Size of baby: measuring the crown-rump-length of the baby, which indicates gestational age
- Location of pregnancy: checking the pregnancy is developing normally in the uterus
- Gestational sac: the baby grows within a small sac, and the size and appearance are assessed
- Heartbeat: confirming the presence of a heartbeat and measuring its rate
- Pelvic organs: checking the uterus for fibroids, and the ovaries for cysts
What Does My Baby Look Like At The First Trimester Ultrasound?
Your baby’s appearance will vary, depending on when your first ultrasound sound is performed.
- Before 5 weeks gestation, ultrasound can’t detect the developing pregnancy. However, the lining of the uterus (endometrium) will appear thick and one of the ovaries will have a cyst (corpus luteum). This cyst will gradually disappear as the pregnancy progresses.
- At 5-6 weeks gestation, a transvaginal ultrasound will detect a tiny gestational sac. The baby is only a few millimetres long and the heartbeat is unlikely to be detected yet. The yolk sac, which looks like a small circle, is also visible, inside the gestational sac. This confirms there is a developing pregnancy even before the baby can be seen.
- At 6-7 weeks, the embryo is measured from one end to the other and will be about 5-9mm long. The heartbeat is now detectable.
- At 8-11 weeks your baby will be detectable with transabdominal ultrasound and is around 10-12mm long.
- At 10-12 weeks gestation, the embryo is clearly recognisable as a baby – with head, body, limbs and organs. Your baby will be about the length of your little finger and moving around in the gestational sac.
Does Ultrasound Hurt?
Having a transabdominal ultrasound doesn’t hurt. The pressure of the transducer on your belly and baby might be uncomfortable at times, especially if the technician needs to press hard to see a certain part of the baby better.
This pressure can be especially noticable if your baby isn’t in a good position and the technician encourages your baby to move by poking or pressing down. Tell the technician if you are feeling any discomfort. Some women can find this very distressing and are concerned for their baby’s wellbeing.
You might also have the extra pressure of a full bladder, which can become painful.
A transvaginal ultrasound might feel uncomfortable, especially if you are nervous or worried about having the scan performed. As far as possible, try to relax. Breathe slowly and deeply to avoid tensing your pelvic floor muscles.
If you’ve had an injury or pelvic pain, the pressure of the internal transducer can be painful. Before the ultrasound, make sure you tell the technician about any concerns you have.