Posted on April 27th, 2017 by

3D - 9 Weeks

9 Week Embryo in 3D

Ultrasound Facts vs Common Misconceptions

General Stuff

  • Technically speaking, ultrasound is the study of the subject (the field of ultrasound) and a sonogram refers to the examination itself.
  • Current biohazard testing reveals no ill effects of ultrasound on the fetus, mother, or sonographer. However, on-going tests show increasing levels of heat after scanning for several hours in one area. This is much longer than the time required for performing a diagnostic test. It is also why the prudent use of the technology is recommended. The benefits of the information from diagnostic exams for patient and physician currently outweigh the risks.
  • Ultrasound is just that..sound that is a frequency beyond human hearing. Nope, your fetus cannot hear it, either!
  • Someone newly trained in the field earns the credentials of DMS or Diagnostic Medical Sonographer. He or she has completed some sort of formal or on-the-job ultrasound training. This person is usually relatively inexperienced and has not yet passed the registry examination. This person should have direct supervision in performing your examination.
  • RDMS stands for Registered Diagnostic Medical Sonographer. A sonographer earns these credentials when she has passed a registry examination in his/her ultrasound specialty. This person will typically have at least two years of experience. He or she should be qualified to do your examination without direct supervision.
  • 4D is 3D in motion or a live 3D image.
  • Most people are familiar with 3D imaging as a fun way to see the outside of their baby. This best utilized later in the 2nd trimester and mostly used for the face, hands, or feet.

    Performing Your Exam

  • Every practice is different. Most physician’s order a first-trimester ultrasound examination to date the pregnancy. This is usually performed with a vaginal probe. If no other problems necessitate another scan, the next is performed around 18-20 Weeks. Most women know this as the anatomy screen where the fetus and maternal parts are evaluated for abnormalities. This study is not ordered to determine sex! And determining sex at this examination is never a guarantee nor should it be an expectation.
  • The health of your pregnancy determines whether you will receive more ultrasound scans after your mid-pregnancy anatomy screen.
  • 2D ultrasounds are the grey-scale images you might recognize during your diagnostic examinations. Occasionally, a high-risk practice will usually also use 3D to assist in visualizing a fetal abnormality. We also frequently use the technology for GYN scans to attempt a better look at uterine shape and/or IUD placement.
  • The ultrasound machine is never “wrong” in determining fetal sex. It is the observer who is incorrect. Guessing the wrong sex can be due to one or a combination of many factors. It is possible your baby was in a difficult position to see well. Maybe you were too early in your pregnancy for an accurate guess. Additionally, an overall poor view can also limit fetal sex determination.
  • Ultrasound can never predict how much your baby will weigh at birth. All we can do is measure your baby’s head, belly, and femur for an educated guess at the time of your scan. We can typically track a trend for large or small babies. And we know the average gained weight in the last few weeks is about 1/2 lb per week. However, every baby is different!

Your Ultrasound Results

  • Yes, the sonographer can read your examination. But your OB/GYN physician or radiologist must ultimately interpret the images and report we create. Only your physician can legally give you results.

Patients ask me these questions on a very regular basis. I hope it was helpful!

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Posted on January 23rd, 2015 by

One thing Moms wonder about most while waiting for the big day is how much Baby she is actually going to have to push outta there!  If it’s not your quasi-friends telling you you’re huge or a perfect random stranger asking if there are two in tow, then it’s your bathroom scale not-so-gently reminding you of your ever-changing shape. You see the numbers creepin’ up like your too-tight fave pair o’ jeans. If you’re really lucky, you just failed your two-hour glucose. Just when you thought pregnancy was going to be your temporary ticket to Oreotown, your doc is telling you to find a new love for wheatgrass shakes and to hang it up on the Beautiful Bavarian you have a date with for breakfast every day…your husband should be jealous the way you eye those things. I know, I know. I could eat half a dozen of them myself and I can’t use the excuse of growing a human or “Baby wants it; he told me”. Of course, you could use the disclaimer my old Italian mother swears by..if you crave something and you don’t let yourself have it, your baby will be born with a birthmark in the shape of that food somewhere on its body. I kid you not; she really believes it. All I can say is it’s a good thing it’s only an old wives’ tale or there would be an awful lot of gestational diabetes babies out there born looking like pizza and french fries.  Hmm, I wonder what an ice cream birthmark would look like? A dripping cone? The whole carton?

I guess one of the favorite pastimes of Moms today in this age of quickly-changing technology is consulting the highly-revered but often-times inconsistent daily app. You want to know if your weight gain is normal, if it’s too high or too low. Was quasi-friend right to tell you not to have that second piece of cake? Personally, she’d be no friend of mine after that. Let them eat cake! Or it’s “Aw, my baby is an eggplant today.” Huh??

So, knowing we have this insatiable appetite (no pun intended) for knowing everything everyday or at least being able to look it up and get some sort of answer, is it any wonder we wonder at all about the weight of our babies, too? This is where one role of ultrasound is important. Even though very subjective (as ALL ultrasound is), knowing how to take good measurements of your baby provides your doctor with some really important information about fetal well-being.  Read on from One Confused Momma who was originally confused about gender then more confused about Baby’s size!

ocm:  Okay so new question!! How accurate are ultrasound measurements as far as baby’s weight?? I had my last one today and she measured him at about 4lbs and I’m only 29 weeks and 3 days.

wwavb:  Hi, again! It varies and it’s not an exact science. Generally speaking, the measurements we take of the head, belly and femur are subjective but have a standard deviation of 3wks in the 3rd trimester. The total weight estimation will probably be somewhere around +/- a half pound or so at this gestational age. If we get a measurement that is a couple of weeks ahead, it can still be very much within normal limits for size. We also see that babies can grow in spurts so if the belly measures big now, it doesn’t mean it will nearer your due date. We can also determine through serial scans if a baby is trending large or small and your physician will follow fetal growth accordingly. So! All that being said, if your doctor feels baby will be big, he or she will likely keep an eye on size. This is a good question for your doc at your next visit!


I don’t have one with me now but I’ll print a report of a 3rd trimester biometry (fetal measurements) with an EFW, or estimated fetal weight, and share it with you next week, if not tomorrow!

I’ll also add here that your doctor uses the fundal height or the measurement in centimeters to the top of your uterus he/she obtains when you go in for visits to determine growth in generalities. If your uterus measures really large, your doc may order a sonogram to see if Baby is big or if you have too much fluid, polyhydramnios. We see a lot of this, by the way, and don’t always have an explanation for why it’s there. Conversely, if you measure pretty small, your doc may want to find out if Baby is not growing appropriately and to ensure you have enough fluid. Mom’s body type can also influence how your belly looks, too! You can spend all day downloading apps but, as always, questions pertaining to you and your pregnancy and baby specifically can only be answered by your doctor! (And not Dr. Google)

At the end of the day, our shapes during pregnancy are as different as we all are different from one another. We have to quit comparing our bellies to those highly polished on the cover of Vanity Fair and even one another and know we are doing what is right as long as we are adhering to our doctor’s guidelines! Sometimes it’s out of our control and our babies end up too big or not thriving well. Either way, that’s why you have people like me around!

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Posted on May 22nd, 2014 by

Here’s an email I received from a UK reader asking about determining Baby’s size/weight.  Read on for my response!

reader:  Hi, I was just wondering how accurate scans are at estimating weight ? I’m 36 weeks +1 and I had a growth and reassurance ultrasound today.  Baby was perfect 🙂 and they estimated 7lbs.  This is my 4th child and the only full-term baby I have had was my last and he was 7lb 10.  I am a little worried this baby is going to be a 9 pounder and that I’m going to have a difficult labour.  This is my last baby so I really don’t want to spend these last weeks worrying over nothing so any info would be gratefully appreciated.  Thanks in advance.  I love reading your blog!

wwavb:  I love my UK readers!  First, let me say I am happy you found my blog and are enjoying it. Thank you so much for saying so!  I truly hope you’ll spread the word and please subscribe for future automatic posts!

Now on to your question. I’m unsure what the discrepancy is in the UK for fetal weight. Our machines may be calibrated slightly differently here in the states. That being said, 1lb +/- is not unheard of and sometimes can be greater depending on the level of skill of your sonographer and fetal position which can make measuring baby more difficult and less accurate, which is precisely why it’s called “estimated”.

If your baby is at 50% or thereabouts, it means he is average in size and will gain on average 1/2lb /wk from here on out. If your baby is measuring bigger then average (which I wouldn’t know without seeing the individual % for each measurement), it’s feasible chunky monkey could gain a little more each week.

Just know that if this baby ends up being larger doesn’t mean you’ll have problems delivering!




I’ve definitely posted on weight before as it is a very often received question!  Everyone wants to mentally prepare for what they are going to have to push out of there.  Check out one of my prior posts on EFW!

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Posted on March 31st, 2014 by

I commonly get questions about the report as I pull up this page on the monitor when I am revealing Baby’s weight after taking a biometry (that is, the measurements of Baby’s head, belly and femur).  Patients usually want to know why the measurements I took differ from the current gestational age.  The fact is they can..this is not an exact science so even a difference of a week can be totally normal.  Sometimes, a large difference can simply reflect a dating issue, meaning you are either farther or less along than you thought.  Your doctor knows how to differentiate between the two.

Check out part of the report below.  This is an old exam on a Baby B who was growing just fine!


First, notice GA.  This is the Gestational Age of Mom currently.  EDD of 8/15/2007 is the Estimated Due Date determined earlier in the pregnancy which corresponds with the GA.

Below that, you’ll see AUA or Actual Ultrasound Age.    It says 19w3d, a couple of days farther along.  This is merely an average of all four measurements taken and is considered consistent with GA, meaning her due date will stay the same.

The biometry consists of the BPD (width of the fetal head), HC (head circumference), AC (abdominal circumference) and FL (femur length).  The names in parentheses refer to the physicians whose charts for these measurements are programmed into the software.  The values are taken in centimeters and each one represents a GA based on that measurement.  You can see that the BPD measured 8d larger.  This is totally normal.  All the other measurements were pretty close to GA within a couple of days.  Again, these all demonstrate normal growth.

Below the dimensions you’ll see EFW or Estimated Fetal Weight calculated in grams with a small standard deviation and also displayed in ounces.  This is determined by the four above measurements entered into the system by the sonographer.

Below that are ratios of these measurements.  If baby isn’t growing properly, it will reflect here but we will also see that in the individual measurements.

Below that is an M-Mode or Motion Mode which demonstrates the fetal heart rate (HR) taken.  120 – 160bpm or beats/minute is totally normal.

This is only a small portion of a report on twins but enough to explain Biometry.  This concludes Ultrasound 101.

Have a great day, people!

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Posted on March 15th, 2014 by

Or, rather, Estimated Fetal Weight.  This is the approximate weight of the fetus after we measure the head, abdominal circumference and femur.  Our machine takes this information and plugs it into the software to estimate Baby’s weight.  I’ve posted on BPD, HC, AC and FL before so I won’t focus on HOW we get those measurements today, but instead, the accuracy of them.

I am asked several times per week, “Now how accurate is this weight?”  Are we always right on with birthweight?  No.  Are we always close?  Another no.  But MOST of the time, we are.  It is an educated guess and based only on the measurements WE take and there are many variables that play into obtaining those properly.  As baby gets closer to the EDD (Estimated Date of Confinement – don’t ya love that acronym??!  So appropriate!), Baby gets bigger, the head becomes more engaged and the fluid can start to diminish a bit.  There is only one right way to measure Baby and all of these things make her harder to see and these measurements more difficult to obtain, especially depending on Baby’s position.

Also, Baby is packing it on in the last month!  Average growth is about 1/2lb per week!  If you’re baby is trending heavier, Baby will usually gain more than the 1/2lb and if trending smaller, then less than 1/2lb per wk.  This is why when a patient comes in at 32wks and asks how much I think her baby will weigh at birth, I always say “If I could predict that, I could have retired a long time ago!”  Sadly enough, we don’t use a crystal ball.  Sometimes babies grow in spurts, too.  We might see a huge head at 30wks and a few weeks later see that everything else caught up.  So…..NO WAY to predict!

Technically, our software tells us at term to figure plus or minus 1.5lbs.   However, IF I feel that I am getting really easy and accurate views of the head and belly (especially the belly since most of the EFW comes from the AC or abdominal circumference), then I feel pretty good to say that I may be over-estimating by about a 1/2lb.

Remember, if you get an ultrasound and an EFW at week 38 and you deliver at 39, don’t forget to add in that extra poundage!

Here’s to a fat and happy fetus!

And if you have stories you’d like to share or questions about weight, feel free to email me or comment on this post!

Thanks for reading,

wwavblogger 🙂

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Posted on January 21st, 2014 by

Or to many patients..the scan where I can tell the gender.  This scan is done typically between 18 and 20wks.  I know I have said this in the past but let me clarify!  This examination has absolutely, positively nothing to do with any need for determining your baby’s sex.  People usually want to tie the two together; “I’m having this scan and now we can find out.”  I have to stress here that you cannot ALWAYS find out gender at this scan and no one will ever guarantee that you can.  Most people understand this.  If any of you read my rant last week, you get it that some people (God help them) don’t.

Let me go back a little bit here.  Ultrasound was initially created as a means of complimenting your physician’s diagnostic puzzle…a little helper, a way for him/her to see a little of what is going on in there so that he can educate you and so that you can be better prepared to make some important decisions in the unfortunate circumstance that something is not developing properly.  Somewhere along the way, ultrasound got better and became the circus that it is today where people show up with herds of family and expect them all to come in for this examination.  At the end of the day, this IS still a medical examination; my job is to find problems and, hopefully, to rule them out.

We have a long list of things to document, meaning we have to find them on your fetus and take an adequate representative image of each organ and measurement.  Some of the things we look for on a routine scan are as follows:

Cervical length – we measure the length of your cervix.

Placenta – we grade it and tell your doctor where it is located.

Amniotic fluid – we do a subjective assessment, general eye-balling of how much is in there.

We measure your baby:

The head from side to side (BPD or biparietal diameter) and around (the HC or head circumference), around the belly (the AC or abdominal circumference) and the femur length (FL).  These measurements estimate a weight which is usually about 8ozs. at about 18wks.

We document internal organs and other structures:

Brain, orbital lenses, face, upper and lower extremities, heart (very basic views), spine, stomach, kidneys, bladder and umbilical cord insertion and vessels.  We check to make sure these things are present, located where they are supposed to be and look the way they are supposed to normally look.  Yes, we have to know the difference!  Some of the changes we are looking for measure literally in the millimeters.  If all parts look normal, we assume they are functioning properly.

After we take all these images, we formulate a report for your doctor in great detail regarding the above parts.  If something is not well seen or limited because your baby was not in a good position, he/she wants to know that, also.  Usually, if your baby doesn’t cooperate to allow us to see everything we’d like, your doctor will typically (at least ours do) send you back in about a month to attempt a recheck.

Let me capitalize the following statement.  ONLY YOUR DOCTOR CAN DISCUSS THE RESULTS OF THIS SCAN WITH YOU!!!!!  NOT me.  Never, never, never the sonographer.  For those of you who have had the terrible experience when we suspect something is wrong, you have a hundred questions and your doctor is the only one who can answer them for you properly.  Your doctor is the one with whom you have the important relationship.  He/she wants to be the one to give you unfortunate news about your baby.  These patients will usually be referred on to MFM or Maternal Fetal Medicine which are doctors who specialize in high-risk OB.  They will scan you again and give your doctor their opinion on what they believe is going on and how your pregnancy should be managed in light of the problem.

So!  Nowhere in the report is there a space to include gender.  That’s because it is not important to the health of your fetus and your doctor doesn’t really need this information.  We know, however, that it is important to those of you who want to know.  And there is nothing wrong with wanting to know!!!  Believe me, I couldn’t wait to find out myself!  I did have to scan myself for 3wks, though, before my own kid would cooperate!  True story.

We love a fun family and love being able to give this news when we can.  What we don’t like are the people who don’t care about anything else, are demanding of us to give them gender information and then ask us 400 times if we are sure of what we see.  As you can see, we have a big job to do which requires time and focus.

It’s okay to find out your baby’s sex.  It’s okay if you don’t!  It’s okay to even have a preference.  It’s just not okay when that’s all that matters.

Questions??  Great!  Email me and I’ll answer what I can!

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Posted on June 21st, 2013 by

Who knows???  We don’t have a crystal ball, right?

Even so, that is a question I get most every week.  If I could determine THAT with any accuracy, I’m sure I could have retired a long time ago!  The only thing ultrasound can really do is a biometry to estimate an approximate weight at present, called an EFW or Estimated Fetal Weight.  We do this by measuring your baby’s head in two dimensions, a circumference of the abdomen and a femur length.  These measurements are converted by the software into grams/pounds and the result has a standard deviation of about +/- 1+lbs in the 3rd trimester..or +/- 1/2 lb if you’re really good;)  All measurements, as all of ultrasound imaging, are extremely technically dependent and can vary quite a bit.  As sonographers, we are trained to know which views provide the most accurate measurements which are universally standard; however, sometimes baby’s position makes it difficult to obtain them adequately.  The EFW really provides just an educated guess since we can’t actually put baby on a scale.

These individual measurements tell your doctor whether baby is growing adequately, not enough or too much.  Either far side of average and you may find yourself getting scheduled for more ultrasounds to follow baby’s growth.  After all, nobody wants to push out a 12-pounder!!

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