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Pregnancy

No Yolk sac found at 5 weeks 2 days

09/08/2009

Question:

Hello, my last period was July 4th so according to the doctor I should be 6 weeks and 6 days pregnant. My HCG levels 8/14 were at 1801, 8/17 were at 2784, and 8/19 were at 4073. 8/17 had an ultrasound where UT was able to see a gestational sac but no yolk sac and not able to measure the gestational sac because it was small. UT said I was only 4.5 weeks. Today 8/21 another ultrasound was done and the gestational sac got larger but no yolk sac found. UT said I was 5 weeks 2 days and they dont see a yolk sac till around 5.5-6 weeks sometime. I told the Dr. I took a pregnancy test on August 7th and it was positive. She said for a pregnancy to be positive you have to be 4 weeks so she said more than likely this is not a viable pregnancy and I may miscarry. However, she said I may have ovulated later. She said it could go both ways but I have another ultrasound scheduled for Monday to see if they can see a yolk sac and I took another blood test today to see if my levels are still raising. What do you think about this? Is it possible for me to have a positive pregnancy test on 8/7 but be only 5 weeks and 2 days pregnant????

Answer:

Dating a pregnancy can sometimes be complicated.  If a woman has regular periods every 4 weeks, she would usually ovulate and possibly conceive 2 weeks after the start of a period.  The conception would then implant in the uterus the third week, and make enough hormone to show up on a urine pregnancy test around two weeks after conception, or just about the time that the subsequent period would be due.  This would be called "four weeks" of pregnancy because it is measured from the time of the last period, even though the woman might actually have only been pregnant for one week!

Once a normal pregnancy starts making "pregnancy hormone" or HCG, the level continues to double every other day until about 8 weeks.  When the level reaches 1500 or so, the pregnancy can usually be seen with a vaginal ultrasound, but may be too small to recognize.  By five weeks (or three weeks from conception) the yolk sac is usually visible, and by six weeks (four weeks from conception) a small embryo may be seen.

Your doctor has given you a correct appraisal.  I hope your further testing helps to shed light on the issue.

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Response by:

Jonathan  A Schaffir, MD Jonathan A Schaffir, MD
Clnical Assistant Professor of Obstetrics & Gynecology
College of Medicine
The Ohio State University