Hi Charissa! 

Thanks for sharing about subchorionic hemorrhage and placental hemorrhage. It important to note the location of the bleed in relation to the placenta to rule out placental hemorrhage. 

Another differential for the 2nd image is twin gestation. Although that can be misdiagnosed due to a hematoma being large enough to mimic the size of the gestational sac. In that case we can differentiate the two diagnoses by being aware of the consistency between the two fluid collections. If one fluid collection has a fetal pole and yolk sac and the other does not it may be indicative of a normal presentation of a hematoma. Or the twin gestation diagnoses could be fact and the presentation is abnormal where one embryo did not form leading to possible diagnoses of twin transfer, abortion, or blighted ovum. And hCG levels definitely play a part in diagnosis. 

Hi Charissa, 

Thanks for pointing out that with placenta hematoma there will be no bleeding, but with subchorionic hematoma there will be. Just a simple reminder 25% of pregnancies result in bleeding during the first trimester and about 50% of those will miscarry. This can be quite scary for mothers to experience.

According to an article from, VeryWell Family, " Under most circumstances, women who develop subchorionic hematomas enjoy otherwise normal pregnancies and go on to have perfectly healthy, happy babies."  This makes me happy! 

Do you know what the risk of of complications are, related to a subchorionic hematoma?

Hey charissa-

I'm so glad we are starting with subchorionic bleed. The one and only first trimester I saw at my site, I now realize this patient probably had one. At the time I was so excited because I thought the patient was having twins! I remained calm and kept my poker face. When my CI and I left the room I immediately looked at her and said, "Twins?!" She let me know very quickly that it was not a viable pregnancy (singular). At that time I didn't realize what the second 'gestational sac' was. Now thinking about it, I bet it was a subchorionic bleed. It was two cystic sacs that were just adjacent to each other and neither with a yolk sac (which by that time) there should have been one. 

This is crucial to be able to identify a subchorinic bleed from a pseudosac from a gestational sac and so on. 

Thanks for the share!

Hi Jackie, 

I strongly agree that "dates, labs and clinical history," is an important factor for differentials. I was so blown away today when learning that all we can really do is describe the fluid collection without being able to know what it truly is. Abnormalities can be very tricky. It was a little hard for me to keep up and correct me if I am wrong, pseudo sacs result from a blighted ovum? And will the blighted ovum or pseudo sac resolve on its own? 

Hi Jackie,

I completely agree that dates, labs, and clinical history are absolutely vital to the list of differentials and which way you’re going with the picture you’re trying to paint for the radiologist . My concern is what happens when the woman comes in with irregular people or the one with the unreliable memory. Then the picture becomes murky because are the lab values off due to a problem with the pregnancy or because the information given was off? Is there a time when we don’t necessarily listen to the patient and go with the pictures and lab values? This is my biggest concern with blighted ovum versus pseudo sac and others.

Hi Ellen, 

You did a wonderful job explaining the normal mid gut herniation versus the abdominal wall defects. Can you help me identify the differences between the 3. I know with Omphalocele the herniation protrudes through the navel and with Gastroschisis it protrudes besides the belly. How is the limb-body wall complex described? 

Ellen, thanks for including the measurements of normal gut herniation, this can really help in times of panic and confusion when seeing this for the first time.

Ellen, 

You did a magnificent job outlining the normal process of the midgut herniation and abdominal wall defects. It is understandable why the CRL is used in dating after it is obtained instead of relying on inaccurate dates, especially when it comes to normalcy versus pathology and how ones care may continue down the road. I can appreciate how much of our job is obtaining normal picture, while staying alert and using critical thinking for the times when it’s not. 

Hello Maria,

After reading your post guess what came to mind? the cephalocele and cystic hygroma. i brainstorming of all the CNS abnormalities however these two kinda stuck with me. 

The cephalocele is an abnormally in the fetal brain resulting from the calvarium not closing properly and as a result the meninges are not correctly encapsulated. It will appear as a solid mass with a protrusion of the skull. It is so important to take our time with the skull and not miss any pathology.

The cystic hygromas on the other hand are a sac filled with fluid so it will appear anechoic. Cystic hygromas usually derive from the fetus having a lymphatic system problem. The cystic hygroma will appear around the neck on the posterior side and also around the upper thorax. During exams having our gain and TGC at an appropriate level (optimizing) can help us get better images and help us determine sacs from calcifications.

Hey Maria-

Thanks for comparing those two! Some CSP is okay, but too much is worrisome. Just remember that we are not really supposed to diagnose Dany Walker Malformation until the 2nd trimester. This is because there could be a false-positive diagnosis can be made at gestational ages of less than 18 weeks.

"Cerebellar malformations, particularly subtle findings such as Dandy-Walker variant, should not be made at less than 18 weeks gestation because it is possible that the development of the cerebellar vermis is incomplete."

However, it would be super important for us to document our findings a bit more than we normally would. This would let the radiologist know that we are seeing something a bit abnormal at this time. 

Here's the site in case you'd like to read a bit more about it. https://rarediseases.info.nih.gov/diseases/6242/dandy-walker-complex/cases/52163

Hello Heather,

This is a great example of how the corpus luteal cyst can be confused for an ectopic pregnancy. I also had a hard time distinguishing the difference in quarter three. Another, way you can tell the difference in addition to checking the pregnancy test and HCG levels is by asking patient history, because if she has a history of ectopic, cesarian, or heterotopic pregnancy than evaluate further for another ectopic.

While reading your response I thought about the Theca Lutein cyst which are common in first trimester molar pregnancy. Theca lutein cyst are usually bilateral, they are caused by increased level of HCG due to the molar pregnancy. It is so important during all of our OB anatomy scans to always look at the mothers anatomy because evaluating the ovaries during a first trimester could give you lots of information. I read that the Theca lutein cyst are commonly incidental finding which, kinda goes with Dr. Michelle's story.

Massive Theca Lutein cyst    

Whoa heather.. the ring of fire around corpus luteum cyst and ectopic pregnancy is a hard one to differentiate. I tried reading the summary on resistive index and like you, I'm trying to make sense of it. A patient came in the other day and had a cyst in her ovary, she didn't have her period for 3 months, but her hCG levels didn't indicate a pregnancy. I was trying so hard to figure out what was happening. She was in pain and bleeding. My first thought was an ectopic pregnancy, but because her hCG levels weren't matching, I thought an abortion. She did have free fluid, so thenI thought a ruptured cyst. I was so curious and even the tech couldn't call it.  I'm actually going to go back and review the report, because I want to know what the radiologist called it. These differentials sure are tricky. 

Hello Heather, 

i'm glad you choose this topic specifically the corpus luteum. This week in clinicals we had a referral for ED patient early pregnancy .I got excited as I don't see much ob let alone first trimester. Reason of referral was to rule out ectopic due to bleeding. We went over priors. Sonographer and I were making hypothesis as to what it could be. Upon scanning we did see what we thought was the corpus luteum pop some color on there and the ring of fire surely enough confirmed it for us. Its great to know foundation as the corpus luteum could have easily been mistaken for an ectopic especially in early pregnancy as both due have increased vascularity thus looking the same via sono. I will most definitely remember to distinguish one from another is to compare RI as ectopic has greater RI of .7.  Thanks!

Hi Elona, 

These first trimester complications are terrifying. I never realized how many failures are possible during the first trimester. Thank you for reminding us of the measurements of the MSD, this is important to understand so we can accurately asses the scan. It just blows my mind that with a blighted ovum, the placenta will continue to grow and support itself with no embryo. 

I found this blog online about a woman who has experienced a blighted ovum and several miscarriages there after, very saddening that once you have an abortion or miscarriage, the body is at higher risk of getting another. She failed 6 times, but is not giving up. Check it out!

https://www.miscarriageassociation.org.uk/story/ninas-story/

Hi Elona, yes a blighted ovum will be a gestational sac without any signs of an embryo. We know that after 5 weeks of pregnancy the secondary yolk sac should be seen on ultrasound. Also, as a result of a blighted ovum we can see a pseudogestational sac.

Hey Lauren, 

Much agreed that we should know what normal is and if we see something that is questionable we should speak up. Capturing the images and having help from our cohorts is better than missing something that can be pathological. According to Medscape. "Sonographic visualization of a subchorionic hematoma is important in a symptomatic woman because pregnant women with a demonstrable hematoma have a prognosis worse than women without a hematoma. However, small, asymptomatic subchorionic hematomas do not worsen the patient's prognosis."  So although, it is quite scary to have subchorionic hemorrhage, it is safer to have a smaller one that will hopefully resolve on its own. 

As far as the normal gut herniation, do you remember what week it should resolve by? 

Radswiki. “Subchorionic Hemorrhage: Radiology Reference Article.” Radiopaedia Blog RSS, https://radiopaedia.org/articles/subchorionic-haemorrhage-2?lang=us.

Hi Amanda, that is a good observation that many issues do happen to appear more often in women who are older than 35 as well as in women going through assisted reproductive therapies. I did not know that a fibroid has less vascularity than a placenta.

Hi Amanda, 

You are spot on with associating maternal age with pregnancy scans. This is a helpful tip. This is something I will take with me when I begin to scan OB's. You've picked a great differential. I'm sure it's very easy to mistake a contraction for a fibroid, thanks for the advice on going back on the exam to identify if it is in fact a fibroid or just a contraction. 

Do you mind sharing the info on the vascularity between the fibroid and contraction? I'm interested to know how the contraction has more. I found this image on the fibroid, but didn't see one showing the contraction. I was trying to compare. 

Paris, I wish I could see more 1st trimesters, so far I saw only 2 and the sonographers performed them soo fast in like 5 mins! It seemed so simple, but now that we learn how many things could go wrong I know this exam is more then just gestational sac, yolk sac, ovaries and embryo. We really have to scan the mother anatomy carefully to not miss a big problem thats "growing" inside.

Great examples of the abnormal secondary yolk sac and gestational sac. I think as technology advances the first trimester scan will become more and more involved. As for now the most I've seen first trimester is a tiny embryo that I measured the CRL for. It had a heartbeat that we were also able to measure. The secondary yolk sac looked healthy as well. According to this website acrania can be visible around 11 weeks. https://radiopaedia.org/articles/acrania.It's super rare and to my eyes still a very vague image to recognize. Here's to hoping we all get a more first trimester experience soon!

Hi Paris, 

I enjoyed looking at your images you posted. Very well put together. Seeing the different shapes and sizes of the yolk sacs in image (A) is a reminder that, just because we see one, doesn't mean its all good. We must evaluate the entirety of it. For image (B) What would cause the gestational sac not to grow as fast as the baby? and what happens if it never grows? Does the baby get smushed? I'm sadly confused. Image (C) you are 100% right, no secondary yolk sac, no gestational sac! And on image (D) i'm with you on that, I would keep tweaking the transducer, thinking it was operator error, but would never assume Acraina. 

Hi Paris,

I know what you mean about assuming an acrania Dx. Acrania has several differential Dx to consider:

" Imaging differential considerations include conditions such as:

• meroacrania: preservation of occipital bone (sometimes considered as part of acrania spectrum) 4
• anencephaly/exencephaly: has absent/deficient brain tissue as well
• congenital hypophosphatasia
• achondrogenesis
• severe osteogenesis imperfecta: additional findings such as bowing, shortening, or fractures of long bones often aid in distinction from acrania
• calvarial defect(s) due to an amniotic band"

Source: https://radiopaedia.org/articles/acrania?lang=us

Thank you, Jazmin for these images. No matter how many times I see omphaloceles alongside gastroschisis, it really helps to have the visual reinforced. At first glance, or if the image is obscured by maternal structures, it could be easy to mistake 1 for the other. It reminds me of the importance of being sure of dates and details going into an exam.

Hello Liz,

Thank you for explaining heterotopic pregnancy so well!!! I struggled with this concept a little in quarter 3 I wanted to add a photo for those visual learners.

heterotopic photo: IUP/ECTOPIC SIMULTAEOUSLY 

Hi Liz

I like the fact that you bring up heterotopic pregnancies because they do appear to be semi-normal with the one IUP. You may be scanning and see a normal intrauterine pregnancy with a yolk sac and gestational sac, but if you fail to thoroughly assess the adnexas, you could be missing an ectopic pregnancy, which we know to be a crucial diagnosis.

I think one of the biggest screening tests is simply hCG levels. I would think that hCG levels would be elevated, but according to sonoworld.com, “in a heterotopic pregnancy, only careful examination of the extrauterine anatomy provides the means of making the sonography diagnosis”. Although we cannot solely rely on the hCG levels to indicate a heterotopic pregnancy, we can use sonography along with this testing to determine if an adnexal mass is in fact another gestation.

Hi Liz, 

Thank you for clarifying heterotopic pregnancy. I wasn't really to sure the ins and outs of it when I first about learned about it, so i'm really glad you brought it up in our DB.  According to the Journal of Human Reproductive Sciences, they explain, " The incidence was originally estimated on theoretical basis to be 1 in 30,000 pregnancies. However, more recent data indicate that the rate is higher due to assisted reproduction and is approximately 1 in 7000 overall and as high as 1 in 900 with ovulation induction." That is a 13,000 difference from past data to recent data. And saddening for women who's ovaries to do not mature fast enough, they get a treatment for ovulation induction, this increases their risk by even more of having heterotopic pregnancies. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2700683/

This is a great distinction between the two - the decidual reaction, but empty sac and falling hCG versus the remaining yolk sac. There are so many factors to consider when examining such early potential pregnancies. There are a great many clues that present themselves to us just about the gestation sac - shape, size, contents.

Here is an informative recap of first trimester findings from the University of Massachusetts:

https://www.e-ultrasonography.org/upload/usg-19043.pdf

Hi Serina, 

It is very important for a mother to have serial ultrasounds when experiencing a possible Anembryonic/Blighted ovum pregnancy. Remembering, that we can not a call a for sure pregnancy until we see the secondary yolk sac. hCG testing is also an extremely important screening to continue to follow up with, so we can determine if it is rising or falling. Great post! It really amazes me how the little things in the first rimester play a huge role for the pregnancy to be a success. 

Would you be able to help answer this question, how many weeks until it is considered a missed pregnancy or in other words how long does the doctor wait for the yolk sac to appear?

Hey Beth, 

LMP is so important when scanning a 1st trimester. I'm with Michelle, when she mentioned, she doesn't even want to start a scan on a patient without a hCG test, because then your really playing the guessing game. An empty gestational sac can mean a few things, miscarriage or possible be miscarrying, an ectopic pregnancy and of course the anembryonic pregnancy. Correlating the MSD and the hCG is the most important, thank you for sharing! 

Hi Perresha,

During the first trimester, sonographers can see the subcutaneous fluid in the posterior region of the neck of embryos and fetuses. However, only large amount of fluid is associated with a higher risk of chromosomal and structural abnormalities.

Nuchal translucency (NT) is a very important screening test done by ultrasound in the first trimester of pregnancy – from 11 weeks to 13 weeks 6 days of gestation. After 14 weeks of gestation, most of the fluid is usually reabsorbed and the test has no diagnostic value.

To get reliable results, the CRL of the fetus should be from 45 mm to 84 mm. It is very essential that this test is performed by a certified in nuchal translucency sonographer; otherwise, the results cannot be used. Screening by NT can detect about 80% of fetuses with trisomy 21 and other major aneuploides for a low false positive rate of 5%. The combined detection rate of 90% can be reached if first trimester screening tests, such as NT, free β-hCG and PAPP-A, are used together.

It is helpful to know that when the nuchal translucency is <2 mm, the rate of aneuploidy is less than 1% (Knipe). Usually NT < 3mm is considered as a low risk. If we got >3 mm, the differential diagnosis will be an incorrect technique, as very clearly explained by Perresha. In addition, it can be fetal neck skin thickening due to first-trimester hydrops fetalis.  Knowing the results of T1 screening tests will assist us in planning and adjusting our scanning protocols to find structural anomalies usually associated with aneuploides.

Reference: Knipe, H. Nuchal tranclusency. Retrieved from https://radiopaedia.org/articles/nuchal-translucency-1

Hi Perresha, 

Your post was so great. Thank you for showing us the techniques involved with Nuchal Translucency. The two tiny parallel echogenic lines are so helpful identifying whats abnormal. It's helpful that the image only involves that fetal head and upper thorax so we can better asses the overall Nuchal Translucency. The image you showed with the mistaken Nuchal Translucency was hard for me to differentiate. Do you happen to know how many exams one needs to take to become certified to be able to asses the Nuchal Translucency?