What to Expect at Your 7-Week Ultrasound

Although a 7-week ultrasound isn’t routinely performed, there are actually a bunch of reasons why your doctor might want you to have one — and not all of them fall into the “doom and gloom” category.

In fact, the most common reason doctors order ultrasounds before the 12- or 13-week point is to accurately date your pregnancy.

If your pregnancy symptoms don’t match up with your last menstrual period or there’s any confusion about how old your baby is — gestationally speaking — the measurements taken during an early ultrasound can tell your doctor exactly how far along you are in your pregnancy.

Other reasons for an early ultrasound include:

• Confirming twins or multiples. Especially if you’ve had fertility treatments, this might be something you want to confirm ASAP.
• Confirming fetal heartbeat. If you’ve had any concerning symptoms, like spotting or vaginal bleeding, your doctor will want to know if you’re experiencing a miscarriage or what the cause of any unexplained bleeding could be.
• Ruling out an ectopic pregnancy. When an embryo implants outside the uterus, you’ll often have pregnancy symptoms and a positive pregnancy test, even though the embryo isn’t viable. An ectopic pregnancy is a life threatening condition if it’s not treated, so it’s important to diagnose it.
• Checking your reproductive anatomy. Issues with your uterus, cervix, ovaries, or fallopian tubes can cause complications during pregnancy. So, if your doctor suspects you might have a problem — like uterine fibroids, for example — they may want to have that info right away.

Again, it isn’t cause for immediate panic if your doctor orders a 7-week ultrasound. Yes, it could be a worst-case scenario, but it could also just be one where you’re collecting as much info as possible so you can have a healthy pregnancy.

Pop culture has likely taught you that your first ultrasound is a beautiful experience where a technician waves a magic wand over your stomach and you get to stare at a computer screen and see the adorable shape of your baby floating peacefully in your uterus.

But that’s not what happens at a 7-week ultrasound, so let’s just blow that expectation out of the water now. (Sorry!) In most cases, your baby is too small to be seen clearly — or at all — on an external abdominal ultrasound. Instead, you’ll need a transvaginal ultrasound.

It sounds less than fun, we admit, and it is a less-than-fun procedure: A technician inserts an ultrasound wand, called a transducer, a few inches into your vagina until it reaches your cervix.

Then, the technician keeps it in place, adjusting the wand as much as needed to get a good look at the inside of your uterus. It’s not painful, though it may be uncomfortable.

You’ll feel about as much pressure as you do during your annual gynecology exam, for comparison. It does take longer, which can add to the overall unpleasantness, but the technicians are trained to make you comfortable — at least, as comfortable as you can be with an ultrasound wand inside in your vaginal canal.

The good news? There’s no risk to your baby from the procedure and there’s no radiation used. So, while it won’t go down in history as one of your favorite experiences, it can’t cause any harm.

You’re not going to be counting fingers and toes at this ultrasound; the embryo is simply too tiny for clear images to be detected. You may see the general shape of your baby or be able to tell something is there, but it’s also normal to not see anything that looks very much like a baby at all.

One thing you will often see in a healthy pregnancy is your baby’s heartbeat. It could be going as fast as 110 beats per minute or more! If your baby is in a visible position on the ultrasound, you’ll probably see a little blinking or pulsing on the screen (and you should be able to hear it briefly, too).

You may see the following anatomical developments on a 7-week ultrasound:

• Gestational sac. This is one of the earliest visible signs of a pregnancy, and it refers to the fluid-filled space surrounding the embryo. It’s usually formed by 5 weeks of gestation, and it can accurately confirm an intrauterine pregnancy the vast majority of the time it’s seen on an ultrasound. It will look like a clear, dark circular or oblong shape, sharply contrasted with the whitish, opaque appearance of the inside of your uterus.
• Yolk sac. Even before you can see an embryo inside the gestational sac, you should spot the yolk sac. It’s the first thing to develop inside the gestational sac, and it provides your baby with nutrients and oxygen until the placenta develops. It’ll look like a small white ring or bubble inside the sac.
• Fetal pole. This is the first indication that your baby is forming inside the gestational sac. It will look like a thick, whitish shape attached to the yolk sac. Depending on how far along you are, it may be curved or oblong. It can usually be detected by 6 weeks of gestation on a transvaginal ultrasound. This is where you would see the baby’s heartbeat.

Aside from detecting a heartbeat, the point of a 7-week ultrasound is to take measurements of these fetal developments so your doctor has a better idea of where you are in your pregnancy.

That’s why this is often called a dating ultrasound: The measurements are a good indicator of gestational age.

The technician will measure the size of your gestational sac and also take a crown-to-rump measurement of the embryo, if it’s visible. At 7 weeks, your baby should be about 5 to 9 millimeters (mm) in size and the gestational sac will be about 18 to 24 mm.

At this point, fetal development is on a fast track and making large leaps in size from one week to the next.

A gestational sac measuring well below 18 mm will probably reduce your gestational age — that is, your doctor might tell you you’re only 5 or 6 weeks pregnant, not 7. The opposite is true for a sac that measures much larger than 24 mm.

Keep in mind that ultrasounds aren’t a perfect diagnostic tool, and things like the position of your baby can affect the accuracy of the measurements — or whether your technician is able to take them at all.

If the results are inconclusive, your doctor may ask you to schedule another ultrasound in 1 or 2 weeks to try again.

Considering that most people don’t realize they’re pregnant until they’re at least 3 or 4 weeks in — and the gestational sac is the very first thing to form in your uterus — it’s likely that by the time of your ultrasound, you’ll see at least this initial development with a healthy pregnancy.

But you may not be able to see a yolk sac, the fetal pole, the early shape of your baby, or your baby’s heartbeat yet. And if you don’t, try not to worry.

You could be earlier in your pregnancy than you’d first assumed, with a later ovulation window than you’d thought. You could also have a tilted uterus, which can make it harder to see your baby until they’re a little bigger.

That said, the 7-week ultrasound could also reveal a hard truth about the health of your pregnancy.

If there are no signs of pregnancy or inconsistent signs, like a large gestational sac without any yolk sac or fetal pole, it may mean you have a blighted ovum or are otherwise miscarrying. This is very common in the earliest weeks of pregnancy, when the risk is the highest.

If you’re still experiencing early pregnancy symptoms but no fetal growth at all can be found in your uterus, your technician will probably look for signs of an ectopic pregnancy. This may be done along with blood tests and a pelvic exam.

Yes, especially if they’re fraternal. Figuring out how many babies are growing in your uterus is one of the main reasons for having an early ultrasound.

If your twins are fraternal — meaning, two different eggs were fertilized — there will be a separate gestational sac for each baby. If you’re estimating your pregnancy accurately, multiple sacs should be pretty visible on a transvaginal ultrasound at 7 weeks.

If your twins are identical — meaning, one egg was fertilized but then split in two — there’ll only be one gestational sac; however, more than one yolk sac, fetal pole, and heartbeat may be visible.

Again, keep in mind that ultrasounds aren’t foolproof. You may not be far enough along in your pregnancy for all these things to be detected.

And remember that babies like to hide, especially when they have a sibling to hide behind! Multiple gestational sacs may not be visible until a later ultrasound.

Resist the temptation to be alarmed if your doctor orders a 7-week ultrasound; there are several good reasons this test is helpful in the early weeks of pregnancy.

It’s an uncomfortable but harmless procedure that offers important information, including whether your pregnancy is still viable and, if so, exactly how far along you are (and how many babies are growing).