Early Ultrasound Dates off by Two Weeks?

Updated on July 13, 2010
C.L. asks from Middletown, NY
9 answers

I had an ultrasound last week because I cannot remember when I had my LMP. Sadly, I had a rough estimate of how far along I was by conception date. When you do it once a month it makes it easier to remember, apparently. :) By that date, I expected to be about 8 wks along. My ultrasound showed 5 wks, 6 days with a heartbeat of 118. I know that conception date isn't accurate because it could be up to 5 days later than the date you did the deed. Even when I add on five days, the u/s is off by a good week or more.

Anyone else have a similar experience with a good outcome? I have a history of miscarriages so I can't help but think this is a bad sign.

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So What Happened?

I called the doctor this morning and talked his nurse. She said that ultrasound results stated strong heartbeat, but as an abnormally small gestational sac. What she didn't know is if that meant abnormally small because I thought it should be further along or abnormally small for it's age.

She talked to the doctor and they're going to do another u/s in three weeks. In the meantime, she basically implied expect the worst, hope for the best. For whatever reason, they're not doing blood tests. Just a new ultrasound in three weeks. It's going to be a long three weeks.

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M.T.

answers from New York on

It's unusual to be 2 weeks off on such an early ultrasound - in the first trimester, each week is very different so a 6 week and an 8 week fetus are remarkably different in development, whereas, say, a 26 and 30 week really are not different except in size
Good luck!

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E.M.

answers from Johnstown on

With our older one, our due date was Dec. 1. With us living away from family, we were told not to go anywhere for Thanksgiving because I was going to go early. Then I was told not to go anywhere for Christmas because I was overdue and would go anytime. Jan. 17 we had to be induced. After that experience, my faith in technology deminished extensively. Congratulations!

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S.C.

answers from Fort Wayne on

YES! With my youngest I was WAY off! I don't know exactly how I was so far off, but I was! Like you, I was pretty confident that I was much farther along than I was. Usually the early ultra sounds are the most accurate for determining due date. Once the baby really starts to grow, it's more difficult to determine.
Congrats :)

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D.W.

answers from Philadelphia on

I was off by five days. I think that it took five days after the time I had sex and the time I concieved because I wrote down when I had my lmp and when I had sex. My son is now almost three and is doing well. I had a miscarriage before I had my son. I would have them test your estrogen levels. The can do a test to see how your hormone levels are. Good luck and do not stress yourself out. Congrats.

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S.S.

answers from Cincinnati on

this happened to me and to my mom when she was pregant with me. My mom didnt have an ultrasound but was told that her due date (guessed by her measuurements) would be in early may. She knew this was right and I was born in june. They told me that my son would be born around the end of august then after my ultrasound they changed this to the begining of august (he ended up born in the middle) even though there would have been no way I should have been ovulating then.

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S.V.

answers from Rochester on

I was told to expect the worse and plan on having a miscarriage over the weekend sometime when i had my first u/s with my second daughter. Because her sack was measuring two weeks behind what I knew it should be (we only had sex once so I know when i got pregnant). The doctors sent me for blood tests to check my levels and after teh weekend, they called meto say the levels were where they should be and wanted to send me again and if the levels were still up they would do another u/s. Well needlessto say I have a healthy baby girl, she had to be induced at 42 weeks. She's always just been on the little side. Good luck I hope everything works out for you

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K.S.

answers from Kansas City on

With my first pregnancy I had three different due dates, Last day in August, Beginnig of the last week, and somewhere around the 3rd week. It changed so many times I lost track. My Dr. scheduled an induction on Aug 13th. He decided to come on his own on the 6th. So, my pregnancy was waaay off! My second pregnancy stayed the same, the whole time. Each pregnancy is different. Hang in there and don't add anymore added stress.

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L.D.

answers from Albany on

I'm surprised they saw the heart beat at that point as that usually isn't detected (I thought) until about 7 weeks. Plus, my 4 children's heart rates were never below 165 or so. It may be nothing but I can see why you would be concerned.

Did your doctor do bloodwork to check your HCG levels? I would hope that with your history and the almost 3 week difference that he/she would repeat the sonogram and bloodwork in a couple of weeks. That would give you your answer.

I pray everything turns out perfectly for you.

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P.K.

answers from New York on

Since you really do not know your last period, I would not be too concerned
right now. Think they will do another at 8 weeks. However, not sure of
that. Try to relax. What did your doctor say?

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