The First Trimester: 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.

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.

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.

One of my hopes by sharing these stories and links is that women who know of other stories or have their own success story will share them here as well.


Story A:
Stacy was sent home to miscarry by her doctor because her yolk sac was enlarged. Her yolk sac grew to 9mm. Her baby was born perfectly healthy.
Read Stacy's story,

Story B:
Tulip was measuring about a week behind and the yolk sac measured 9.2mm. She went on to have her beautiful baby.
Read Tulip's story,

Story C:
Tara had a yolk sac measuring 8mm. She's just recently had her 20-week ultrasound and everything looks wonderful!
Read Tara's story,

Story D:
One concerned husband reported that the yolk sac during his wife's pregnancy measured 8.2mm. They went on to have a healthy baby girl.
Read his story,

Case Study:
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."

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The First Trimester: Enlarged Yolk Sac

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