As a twin mom, the general rule is that you do need to have extra ultrasounds (and potentially other tests) to monitor your twin pregnancy and ensure everything is progressing safely. I definitely did – and I’ll detail my ultrasound schedule and exactly what I had below from the moment I tested positive to the day I delivered at full term. Of course, this is all assuming you’re on board with having ultrasounds and tests, because at the end of the day, it is absolutely your body and your choice, including the choice to say no to imaging and testing.
What Scans Do You Get With Twins?
My twins were dichorionic diamniotic, also known as di-di or DCDA twins. So the scans I got were on the more conservative end, as di-di twins are considered the least “risky” with the lowest chance of complications because they have their own sacs and placentas. I know that with other types of twins, specifically those that share a sac and even placenta, there is a risk of additional complications (such as twin-to-twin transfusion syndrome – TTTS) so more frequent scans are recommended. I’ll put a list of this below from an official obstetric source. But here are the scans I had during my twin pregnancy.
My Twin Pregnancy Ultrasound Schedule
Now the first thing to note is that I had a lot more scans in my first trimester than an expecting twin mom normally would. This is because I’ve had an ectopic pregnancy in the past, meaning that my risk of another ectopic is between 10% and 27%, according to research. This is something that my doctor takes very seriously, so ensured I had my first scan very early at 5 weeks to try to see a gestational sac in the uterus. If we couldn’t see this but my HCG was at a good level and rising, this would be when an ectopic would be suspected. So to clarify, for most people who have not had an ectopic or a miscarriage history, they would have one dating scan around 8 weeks, then another scan around 11-13 weeks.
- 5 weeks: two ultrasounds
- 6 weeks: ultrasound
- 7 (almost 8) weeks: ultrasound – dating scan
- 12 weeks: ultrasound – nuchal translucency (NT) testing. Note, I also had the NIPT test around this time too.
- 16 weeks: ultrasound
- 20 weeks: ultrasound – anatomy (morphology) scan
- 24 weeks: ultrasound
- 28 weeks: ultrasound
- 30 weeks: ultrasound
- 32 weeks: ultrasound -my umbilical vein varix was identified at my scan
- 33 weeks: ultrasound
- 34 weeks: ultrasound
- 35 weeks: ultrasound
- 36 weeks: ultrasound
- 37 weeks: ultrasound
- 38 weeks: ultrasound
- 38+3 – c-section day: ultrasound
So in total, I had 18 ultrasounds. Which is quite a lot, although I’ve got to admit, each one felt very exciting to be able to see my babies and make sure everything was alright. I should also note that I was diagnosed with an umbilical vein varix at my 32-week scan, which moved me to weekly scans instead of fortnightly. I believe that if I didn’t have the ectopic or the varix, my ‘standard’ would have been 11 scans in total. You can see the images and reports of all of my early ultrasounds here.
Key Ultrasounds Explained
Among my ultrasound schedule, there are a few key ultrasounds that you should be aware of.
Dating scan (around 8 weeks)
This ultrasound scan is done to confirm that there is a heartbeat, confirming that it’s a viable pregnancy. It also measures the babies and sees if they are on track with the expected date. Your due date can change from your last menstrual period (LMP) estimated due date to your official due date as per this dating scan. It can often change by a few days and is based on how big your baby or babies are measuring. This dating scan is when most people find out they are expecting twins!
Nuchal translucency (NT) test (around 12 weeks)
The nuchal translucency ultrasound looks at all the parts of your growing babies, with a specific focus on measuring the fluid behind the babies’ necks. The result is measured in millimeters. When this number is paired with a blood draw, it rates the probability of each of your babies having one of a few concerns.
For example, you may be estimated to have a 1 in 60,000 chance of a baby having Down’s syndrome. Note: if you have the NIPT done (more on this below) then this scan isn’t always necessary, but it’s important to follow your doctor’s guidance on this one. If you are at a higher chance of one of the chromosomal abnormalities, you may then decide to get a CVS or amniocentesis done. Gender typically remains unknown at the 12-week NT scan.
NIPT test
The NIPT is a blood test, not an ultrasound, but seeing as it’s closely linked with the NT scan above, I thought it’d be worth a mention. The NIPT test has many brand names (including Harmony, Genesis, and Panorama). It’s fairly costly, being about $300-$350. It is a simple blood draw collected after your referral from your GP. You can also find out the gender of your babies if you choose to. The results will show either a low, medium or high chance of having a chromosomal issue. If you do have a high chance then you can choose to get an amniocentesis or CVS which is invasive and does carry small risks, but it is very accurate in detecting issues and concerns.
Anatomy (morphology) scan (around 20 weeks)
The anatomy scan closely examines and measures everything about your baby – their brain, kidneys, heart (including all the vessels), bones – you name it. It also looks at the position of the placenta, the length of the cervix, and how much fluid there is around the baby. Any abnormalities are often detected at this scan, which is a good thing because they can be monitored closely. If you want to find out the gender of your baby, you will be able to do so pretty easily at this scan at no extra cost.
Additional ultrasounds
Beyond the ‘standard’ scans listed above, any extra scans are totally up to you. You can choose to have reassurance scans, private patient scans with your obstetrician (many include this as part of their service), baby position scans (to check breech, transverse or head down), measurement scans, 3D or 4D scans as keepsakes, and more.
If any abnormalities were identified at your morphology (anatomy) scan, then you may also have additional scans to check on these and monitor your progress.
C-section ultrasound
I had my final ultrasound on the morning of my c-section. This is because I made it clear that my preference was a vaginal birth, but my babies had been rotating between head up and down, and my leading twin A had been head up for a few weeks. My surgeon was very considerate and thorough, and despite being all gowned up for my c-section, he did a final scan before I went in to check if twin A had flipped from being head up – no surprises, he hadn’t. This gave me the confidence in knowing it was the right decision to proceed with my c-section and everything went incredibly smoothly.
Twin Ultrasounds Are Longer Than Regular Ultrasounds
Here’s something I wish that someone told me earlier about twin ultrasound scans: they’re much longer than single baby ultrasounds. Which makes absolute sense, given that there are two babies to check. To save yourself the stress of running late, set aside an hour for each ultrasound. I think mine averaged about 45 minutes each, depending on the position of the babies. The further along I got, the longer they got.
Can Twins Be Missed On An Early Ultrasound?
Yes, it’s possible to miss a twin on an early pregnancy ultrasound. I’ve heard of many reasons for this, which include the sonographer seeing the ‘baby’ and failing to examine the rest of the uterus properly for another gestational sac and baby. If you’ve never seen twins on ultrasound as a technician, then it might not come naturally to explore further.
Next, it could be related to the position of the second baby, specifically, when it is positioned directly behind the visible baby on the view and angle that your ultrasound technician is using. It could also be the ultrasound equipment that is being used. It’s much harder to see things on an early ultrasound if you have an abdominal scan, compared with a transvaginal scan. Some scanning clinics also have much more advanced and clear equipment than others – I’ve definitely had a few friends being sent home after their first ultrasound with the question of whether there’s a second baby or it’s a bleed that will resolve on its own, as bleeds can show up with a sac-like appearance.
Which other tests do you have during a twin pregnancy?
Between 24 and 28 weeks you typically do a glucose tolerance test. Here, they take your blood when you first arrive (you need to be fasting, your center will provide instruction for this but I recommend booking your test as early as possible). You’ll then drink a very sugary drink, and they’ll then repeat a blood test either once or twice over the following two hours. You need to remain relaxed and stationary during this time, stay in the collection waiting area, and of course – try not to vomit! The drink usually isn’t too bad. Many people recommend asking for it cold as they find it more tolerable. I liken it to a flat lemonade drink.
If you have any specific questions about twin ultrasounds and my experience, let me know.
