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Pregnant, Ultrasound Showed Small Sac. What Could Be The Meaning?

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Posted on Thu, 18 Apr 2013
Question: I am about 4 weeks pregnant as of 3/27/13 based off the ultrasound I had they said they saw small sac I am wondering is it possible for me to be pregnant from having sex on 2/24 or on 3/4/13?
doctor
Answered by Dr. Aarti Abraham (15 minutes later)
Hello
Thanks for your query.

If you had conceived on 4th of March, then right now you would be 6 weeks pregnant by the ultrasound on 1st April.
Also, if you had conceived on 24th of February, then you would be 7 weeks pregnant by ultrasound on 24th of March.
The weeks of pregnancy are calculated from the date of last menstrual period, and not from day of conception.
ALso, first trimester ultrasounds do have intrinsic error margin of 4 - 5 days.
Hence, you cannot categorically say when you conceived based on the ultrasound.
In viable pregnancies, a transvaginal ultrasound should be able to detect the gestational sac by 5 weeks.
The days are so close by ( merely a week ) that early pregnancy ultrasound can hardly differentiate between the two.

It would help me if you provide me with details of your menstrual cycles - date of your last menstrual period, normal cycle length and duration.
Also, the exact ultrasound report if scanned and sent, or typed word to word, would provide more information.

Looking forward to hearing from you soon.
Take care.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Aarti Abraham (5 minutes later)
I have very irregualr periods so I do not know my LMP the only 1 I can remember is in January but I do not remember the date only that is was also thinking back I do not think I even had a period in feb. So based off whatyou are saying it is hard to tell if those days are the days I conceived or are you saying it is not possible?
doctor
Answered by Dr. Aarti Abraham (3 minutes later)
If you do not remember your last menstrual period, and your cycles are irregular, it becomes all the more difficult to tell you when you conceived, specially when you have to choose between two dates placed only a week apart.
If you can provide the exact ultrasound report, I might be able to opine better.
If the acts were with two different persons, a DNA test might tell you when the conception occurred.
If the two acts were with the same person, it is next to impossible to opine, and it anyways hardly matters, because the pregnancy would be dated by your first ultrasound scan, and not by your LMP date.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Aarti Abraham (7 minutes later)
I have a boyfriend who I see every weekend and every weekend we have sex the dates given are the dates I cheated and I was hoping those dates can be ruled out as a possiblity so I can have better idea for certain that my boyfriend is the father. On the 2/24 I had sex but he pulled out I know that is not a birth control but that weekend I also had sex on 3/4 he pulled out and I douched with water and vinigir the same night and then that weekend I had unprotected sex with my boyfriend and he came inside me. I had a ultrasound on 3/27/13 and they saw a little sac no heart beat they said I am very early in my pregnancy.
So based off the information I gave you does that help with figuring out that I can exclude those days ?
doctor
Answered by Dr. Aarti Abraham (54 minutes later)
What's the exact ultrasound dating in weeks ?
Can you type the exact report ?
Unless you had sex with your regular partner in the intervening period, between 24 th feb and 4th of march, chances are high you conceived with your boyfriend.
EXACT ultrasound report would help, as I repeatedly mention.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Aarti Abraham (3 minutes later)
My exact ultrasound is 4 weeks the doctor said based off that a sac was seen but there was no heartbeat yet I am just starting my 4 weeks. So does that mean that i regualr sex with my boyfriend that it is greater that it is him?
doctor
Answered by Dr. Aarti Abraham (10 minutes later)
4 weeks by ultrasound means that you conceived around 14 days back.
4 weeks by ultrasound means that conception or ovulation occurred only two weeks back.
That would rule out conception by your boyfriend then.
It would all fall in the domain of speculation and percentages till you go for a DNA test.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Aarti Abraham (2 minutes later)
How would it rule out conception by my boyfriend out? Wouldn't mean it a better chance it is him than the guys that happened on 2/24 and 3/4?
doctor
Answered by Dr. Aarti Abraham (2 minutes later)
Yeah
My bad.
I meant that it is more likely that conception occurred with your regular partner, instead of the two exceptions that you cheated.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. Aarti Abraham (3 minutes later)
If the doctor saw a sac when I went from my ultra sound and there was no heart beat that means for certain I must be 4 weeks right because 5- 6 weeks is the heart beat?
doctor
Answered by Dr. Aarti Abraham (6 hours later)
Hi there.
Yes, cardiac activity is visualized generally around 6 weeks.
So if the doctor just saw a sac, you definitely must be 4 - 5 weeks.
Thats correct.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Dr. Aarti Abraham

OBGYN

Practicing since :1998

Answered : 6004 Questions

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Pregnant, Ultrasound Showed Small Sac. What Could Be The Meaning?

Hello
Thanks for your query.

If you had conceived on 4th of March, then right now you would be 6 weeks pregnant by the ultrasound on 1st April.
Also, if you had conceived on 24th of February, then you would be 7 weeks pregnant by ultrasound on 24th of March.
The weeks of pregnancy are calculated from the date of last menstrual period, and not from day of conception.
ALso, first trimester ultrasounds do have intrinsic error margin of 4 - 5 days.
Hence, you cannot categorically say when you conceived based on the ultrasound.
In viable pregnancies, a transvaginal ultrasound should be able to detect the gestational sac by 5 weeks.
The days are so close by ( merely a week ) that early pregnancy ultrasound can hardly differentiate between the two.

It would help me if you provide me with details of your menstrual cycles - date of your last menstrual period, normal cycle length and duration.
Also, the exact ultrasound report if scanned and sent, or typed word to word, would provide more information.

Looking forward to hearing from you soon.
Take care.