Thought I was 6.5 weeks pregnant but...

[stanwhite]

I thought I was 6.5 weeks pregnant based off the last day of my menstral cycle. However, when I went to get my first ultrasound in hopes to hear a heart beat the doctor said I was only 5.1 weeks pregnant. The doctor asked that I go back for another ultrasound in a week to see if there is growth. Obviously, I am very worried. Has anyone had that big of a discrepancy in time from what you thought and what the ultrasound measured? Any comments would be greatly appreciated. Thank you.

[Dragon1973]

Hi there,
Always remember, sometimes dating ultrasounds date the gestational age and some date the foetal age.  I think I have had to ask which date they were referring to when I was pregnant the first time, on a few occasions until I hit my 3nd trimester.  The Gestational age refers to the date from LMP and the foetus age, obviously from the date of conception (which is 2 weeks earlier than the LMP date.)
Here is a good site to see with respect to this common conundrum!  http://www.parentsconnect.com/questions/Gestational_Fetal_Age.jhtml

So, it sometimes is the reason for the confusion.  And as I mentioned, I had to ask the ultrasound technologist which they were referring to on their notes, so I didn't have a heart attack myself!
Hopefully that is the reason, if not - as others have suggested, Ultrasounds are never 100% only because each technician has different abilities and also measure differently from one another, and when I was being monitored every month for a high risk pregnancy, one one occasion I had two different technicians who had differing measurements.  After that happened, I requested the original technician each time I had a follow-up appointment.  That way, I knew her measurements would be consistent.  It was truly nerve wracking!  I may have had to wait an extra few minutes for her, but I had some peace of mind and it was worth it.

In addition to anything I have mentioned, please keep in mind, that while I or others may have extensive knowledge in many areas, you should always seek professional medical advice from your own physician, as it pertains to medical conditions or concerns.
Good luck, and if you have any other questions that I can help you with, please feel free to message me directly.

Sincerely,
Sandi (Dragon1973)
MedHelp Down syndrome Community Leader
& Ds Group Forum Founder/Moderator

[scmotherof2]

lol i went through the same thing. when i found out i was pregnant with my son i just went in for my pap not thinking that i was pregnant but i was so they asked when was my last period they calculated it and said that i was already 6 weeks pregnant so they wanted me to get an ultrasound done when i was 8 weeks so i waited two weeks only to find out during my ultrasound that i was measuring to only be 6 weeks pregnant so the day i found out i was only 4 weeks pregnant my cycle changed. i was confused and first b/c i knew the day of my last period b/c i always tracked it. i also went and paid to get a 3d u/s done and they also said i was around the same as what the doctor told me i was. but during my whole pregnancy i measured right even through my u/s and belly measurements.

[mellymel82]

ultrasounds always measaure a week or 2 off from how far you really are along. They are not 100% accurate. I don't care what anyone says! lol..Not trying to be mean but it is very true. I just went through the same thing. The tech should have told you that they are not accurate at all!