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Enlarged Yolk Sac During the First Trimester?

Updated on March 28, 2015
Touch of Blue III
Touch of Blue III | Source

Yes, There Is Hope Even with a Large Yolk Sac!

When a woman is told she has an enlarged yolk sac during the first trimester, often she is told there is no hope and miscarriage is inevitable.

The reason for this page is that indeed there is hope!

Thanks to the Misdiagnosed Miscarriage site and the numerous misdiagnosed miscarriage stories, we now know that there are women who continue their pregnancies even with an enlarged yolk sac.


I am not a medical professional. The information I share is meant to supplement the information given you by your doctor. If you feel your doctor is not doing enough for you or not willing to listen to your concerns, I strongly encourage you to take what you've learned here and get a second opinion.

Do you or did you have an enlarged yolk sac?

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The Yolk Sac

So, what is this thing known as the yolk sac?

Very simply, the yolk sac provides the earliest nourishment to the baby. Toward the end of the first trimester the yolk sac will begin shrinking as the placenta takes over the job of nourishing the baby.

According to Embryo and Fetal Pathology "The detection of a yolk sac excludes the diagnosis of a blighted ovum because a viable embryo is necessary for yolk sac development." Basically, if a yolk sac is seen during a trasvaginal ultrasound, you cannot be diagnosed with a true blighted ovum. This does not mean miscarriage in not a possibility. It just means this is not a blighted ovum.

Generally, a yolk sac can be seen as early as five weeks during a transvaginal ultrasound. However, many women have said their doctors never saw the yolk sac during the ultrasound and later found their babies. This just shows that, yes despite some medical literature indicating otherwise, yolk sacs are not always visible in viable pregnancies. In my own pregnancy, misdiagnosed as a blighted ovum, nothing was seen in the gestational sac until it was 28.5mm. Even at 21.5mm a week earlier, the gestational sac looked completely empty. Because of my story and many other misdiagnosed stories like mine , we now know that the medical literature is not always correct about when the yolk sac should definitely be seen.

An Enlarged Yolk Sac

what the medical literature says

Most women who are told they have an enlarged yolk sac are told they should expect to miscarry. Since we know women do go on to have successful pregnancies despite a large yolk sac, why are they told this?

WARNING: before you read, remember, we have stories to show this is wrong!

An example of the medical literature gives the reason why. In the Core Curriculum - Ultrasound, the author states:

"An abnormal appearance of the yolk sac correlates with early pregnancy failure. The yolk sac may be too large (6mm). Differentiation of an enlarged yolk sac from the amniotic cavity is difficult but irrelevant because any empty cystic structure whithin the GS larger than 6-mm diameter predicts a failed pregnancy."

Here we have a basic text that gives no hope to women with a yolk sac larger than 6mm. Fortunately, real life stories show that there is hope. Of course, the pregnancy may end in miscarriage but miscarriage is certainly not a given with an enlarged yolk sac.

Some Case Studies:

Very Large Yolk Sac and Bicornuate Uterus in a Live Birth A case report in which a yolk sac was measured at 8.1mm but resulted in a live birth. This report states that "the quality of the yolk sac might be more important than its size."

Abnormal sonographic appearances of the yolk sac: which can be associated with adverse perinatal outcome? This study does recognize the risk of miscarriage with an enlarged yolk sac but only about 1/3 of the subjects miscarried. A better way to look at is that 2 out of 3 women did not miscarry! Keep in mind, even with a normal pregnancy, that risk can run about 20% so there is a slightly increased risk of miscarriage. Miscarriage in NOT written in stone and most women go on to carry their pregnancies to term.

I believe every woman deserves to have no doubt before having her pregnancy ended.

Important New Guidelines for Diagnosing a Miscarriage

The UK is the first to acknowledge that misdiagnosed miscarriages are indeed a problem. The Royal College of Obstetricians and Gynaecologists has revised its guidelines. If your gestational sac is more than 25mm and/or the CRL is 7mm or more, you should wait a week to verify (if there are no complications). If the measurements are less, you are too early to diagnose. For more information (and something to take to your doctor), please, see my new page:

New Blighted Ovum Guidelines! You ARE Being Diagnosed Too Soon!

If I don't reply to you here, please feel free to e-mail me directly at Thank you!

Thanks for reading.

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    • profile image

      Maria 2 months ago

      I will! Baby is now kicking strong and I'm getting more and more excited about this pregnancy by the day. The baby will be born exactly one year after my twins where born prematurely due to preclampsia. (They both passed) so this pregnancy has been very stressful for so many reasons. But for now everything is good and no signs of preclampsia either. I will keep you posted.

    • Cari Kay 11 profile image

      Kay 2 months ago

      I have had moms with similar stories tell me there little ones were just fine. I know it is tough not to worry even in a normal pregnancy but worrying won't change a thing. I hope you update after the birth. (((hugs)))

    • profile image

      Maria 2 months ago

      I was diagnosed with an 8mm yolk sac at 8 weeks. By 9 weeks it grew to 9mm, at 10weeks same thing happened, yolk sac measured 10mm but baby still growing. No scans at 11weeks but we drew blood for genetic testing (panorama). At 12 weeks yolk sac was completely gone, baby's NT measured normal and genetic test was low risk for everything. We are expecting our boy in a few months. Currently 21 weeks pregnant. Anatomy scan was normal except for a 2 vessel umbilical cord which doesn't worry my doctor as all of his organs appear to be normal. Baby is growing on point and even though I still worry if the yolk sac affected him in some way or was there because of something else, I'm very very grateful to be here writing this story.

    • Cari Kay 11 profile image

      Kay 2 months ago

      Dawn, please keep us updated!

    • profile image

      Dawn 2 months ago

      Yay for finding something positive! This past Thursday, I measured 6w4d with a 6.3mm yolk sac and hb of 120. I'm 42 and we did a 3 day fet with 2 embryos. Both are growing, but the second one is measuring 4 days behind with no hb yet and yolk sac looks abnormal. I go back Thursday to see how things are. My dr has a wait and see outlook bc he's seen both healthy pg and mc. I will keep you updated. Thank you again!

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