During your pregnancy you can expect to undergo three ultrasound examinations. The first is scheduled for around eight weeks, the second for five months and the last scan will be performed in the last month of your pregnancy. This article deals with why each scan is performed and what doctors will look for and measure in each instance.
There are two different types of ultrasound tests. The first is the more traditional ultrasound, called an abdominal ultrasound, where gel is applied to your belly and a transducer (the ultrasound wand) is pressed against the skin of your belly to produce the image you can see below.
The second type of ultrasound is referred to as a transvaginal ultrasound. Also called an endovaginal ultrasound, it is a type of pelvic ultrasound used by doctors to examine female reproductive organs. This includes the uterus, fallopian tubes, ovaries, cervix, and vagina. “Transvaginal” means “through the vagina.” so this is an internal examination. Unlike a regular abdominal or pelvic ultrasound this procedure involves your doctor or a technician inserting an ultrasound probe about 2 or 3 inches into your vaginal canal.
An transvaginal ultrasound is only used when the doctor feels it is necessary to have a closer look at the developing fetus. 99% of the ultrasounds performed are abdominal and that is the type of ultrasound you can expect.
Typically, a doctor would use a transvaginal ultrasound for the following reasons;
- to monitor the heartbeat of the fetus
- to look at the cervix for any changes that could lead to complications such as miscarriage or premature delivery
- to examine the placenta for abnormalities
- to identify the source of any abnormal bleeding
- to diagnose a possible miscarriage
- to confirm an early pregnancy
Your 1st Trimester Ultrasound
During an early pregnancy scan, also referred to as a “viability” scan the sonographer or doctor will want to see a few important landmarks. In the early weeks they would want to see an intrauterine pregnancy (in other words the baby is developing inside the womb), a yolk sac and a heartbeat amongst other checks. Yes, at eight weeks, your baby’s heartbeat is audible. Any surprises, like two or more heartbeats, can also often be detected at this point and the ultrasound can determine gestational age and due date by measuring the size of your fetus.
The accepted method for early pregnancy dating is the crown-rump length (CRL) measurement because it’s the most accurate (within about 5 to 7 days) in the first trimester.
This 1st ultrasound is probably the most important of your pregnancy, as it helps doctors determine if there are any early issues that can endanger either you or the baby. If anything is detected, then the doctor can take appropriate action to protect both mother and child. It will also help to set your mind at ease and you can enjoy the first few months of pregnancy free of concern for your developing child.
Your doctor will talk you through the ultrasound procedure and explain to you what the images on the screen are showing. You will also receive a printout of the images to take home and if your clinic has the appropriate equipment, you can bring in a USB device to take the images home in digital format.
Did you know that at 14 weeks, an ultrasound can determine the sex of your baby?
The results of this, and your other ultrasounds, will be digitally uploaded (anonymously, to protect your privacy) to our cloud server from where doctors in the United States and the United Kingdom who volunteer their time, will double check the images to ensure we haven’t missed anything. If a concern is noted, your clinic will immediately contact you for a follow up examination.
Your 2nd Trimester Ultrasound
This is the ultrasound all mothers look forward to most. At this stage in your pregnancy, doctors can tell you (if you want to know) if you’re carrying a boy or girl. You’ll get to see your baby properly on the monitor for the first time and will actually be able to make out a lot more detail. It’s an exciting experience for mothers and fathers (who are incidentally welcomed into out clinics)
We encourage mothers to talk to the doctors about any concerns and questions they may have relating to this scan. In most cases, the 20-week anatomy scan is a positive experience for soon-to-be parents.
A 20-week ultrasound, sometimes called an anatomy scan or anomaly scan, is performed between 18 and 22 weeks of pregnancy. It checks on the physical development of the fetus and can detect certain congenital disorders as well as major anatomical abnormalities. Your doctor will use a 2D, 3D or even 4D ultrasound to take images of the fetus inside your uterus. The ultrasound technician, or sonographer, will take measurements and make sure the fetus is growing appropriately for its age. You may also learn the sex of the fetus at this appointment.
Measurements are taken of the fetal organs and body parts to make sure the fetus is growing properly. The scan also looks for signs of specific congenital disabilities or structural issues with certain organs.
Some specific parts your provider will examine are the fetal:
- Heart.
- Brain, neck and spine.
- Kidneys and bladder.
- Arms and legs.
- Hands, fingers, feet and toes.
- Lips, chin, nose, eyes and face.
- Chest and lungs.
- Stomach and intestines.
The ultrasound technician will also:
- Listen to the fetal heart rate for abnormal rhythms.
- Check the umbilical cord for blood flow and where it attaches to the placenta.
- Look at the placenta to make sure it’s not covering your cervix (placenta previa).
- Check your uterus, ovaries and cervix.
- Measure the amount of amniotic fluid.
You will see the sonographer draw lines on the screen. This line acts as a ruler, documenting the sizes of organs and limbs. They compare these measurements against your due date. In some cases, you might hear you are measuring ahead, on track or behind your due date. If fetal measurements are within 10 to 14 days of the predicted due date, then the fetus is considered to be developing adequately. Your due date will not change unless the fetus measures outside of that time frame.
You are welcome to bring in a USB to upload scan images to. Give this to your doctor or the technician before they start your scan. This facility is only available in clinics that have the equipment to support this.
Your 3rd Trimester Ultrasounds
Our doctors will usually request you to come in for two final ultrasounds in your last trimester, mostly at 28 weeks and 36 weeks, There is increasing evidence that this allows better detection of growth problems and ensures better outcomes for babies and mothers. We’ll deal with the last ultrasound here, arranged for a time falling between your 32nd and 36th week.
The doctor or sonographer will take measurement of your baby to ensure that he/she is growing properly. A careful evaluation of the cervix is also made to ensure it has not begun to efface (shorten) or dilate as a result of the heavier baby pushing down on the cervix. As the time is rapidly approaching for your little one to head out into the world, the position of the baby will be checked to ensure it’s head is down and facing towards your pelvis.
The baby’s movement will also be checked and the heartbeat measured. If previous ultrasounds have indicated that you have placenta previa, or if your provider suspects this condition, an ultrasound examination will confirm that the placenta is still in position over the cervical opening.
Essentially, both these ultrasounds are performed to ensure you and your little one are in good shape for the upcoming birth and any late stage issues can be addressed to ensure the safety of you and your baby. Again, if you have any questions or concerns at this stage in your pregnancy, you should raise these with your doctor.