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Does Ultrasound Give Correct Result About The Foetus Development?

Posted on Fri, 20 Sep 2013

Question: Is it possible to mistake an 12 week fetus for an 8 week fetus via ultrasound? Would it be possible to mistake a 15 week fetus for an 11 week? If all ultrasound EDD match up (7 total) would it be accurate to conclude that the dating is accurate to within a few days? Can an ultrasound at 11 weeks be off by a month?

Answered by Dr. Jay Patel (1 hour later)

Brief Answer:
It can be off by 5-7days in early pregnancy

Detailed Answer:
Hi,

I am dr XXXXXXX and I will try my level best to address your concerns.

The ultrasound in early pregnancy may be off by 5-7 days only in short it may be off by a week, in case of trained and experienced physician. But since here in USA Technicians do perform the job on ultrasound in many case it can be of by 10 days still its will not show difference of greater then 2 weeks.

Its not possible to be off by a month, if its then its not acceptable. (My opinion can't be used as an evidence in court of law, its intended for information only as per the rules of the website)

Thanks for the query. Please feel free to contact me in case of further concerns.
Dr XXXXXXX XXXXXXX

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Jay Patel (5 minutes later)

Thank you for your quick reply. So if I had a sexual encounter of XXXXXXX 18 (2am) - used condoms & plan b 50ish hours later, had a withdrawal bleeding from coming off the pill on Feb 5-8, and sex with someone else all of Feb and all ultrasounds (7,11,14,19,21,&27 weeks) all give EDD of 11/12/13 can I conclude that I got pregnant mid Feb and XXXXXXX has nothing to do with this pregnancy? According to conception calculators I did online they say that I conceived around Feb 19 according to ultrasounds. What is your opinion?
Also all of my ultrasounds have been preformed by different ultrasound techs & line up perfectly. Twice at drs office, 3x at diagnostic center, & once at hospital diagnostic center.

Answered by Dr. Jay Patel (42 minutes later)

Brief Answer:
Yes its seem like you were conceived in feb

Detailed Answer:
Hi,

Welcome back, based on the information it does sound that you have nothing to deal with XXXXXXX encounter since you did took plan-b and did had withdrawal bleeding.

So its makes more sense that you were conceived in mid feb.

Thanks. and as usual feel free to contact me in case of further concerns.
Dr XXXXXXX XXXXXXX

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Jay Patel (24 minutes later)

I know that makes sense, but I also know that both of these have a failure rate. Wouldn't all of my ultrasounds be over a month off if I conceived in Jan? I just want to make sure XXXXXXX 19 isn't a possibility.

Answered by Dr. Jay Patel (10 minutes later)

Brief Answer:
The withdrawal bleeding from plan-b is against it

Detailed Answer:
HI,

Welcome back, the withdrawn bleeding occurred after taking plan-b is the major issue to say you got conceived in XXXXXXX

All the evidence does step in for mid feb conceiving.

So its 99% likely that you conceived in mid feb.

Thanks again.
Dr XXXXXXX XXXXXXX

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Jay Patel (15 minutes later)

Sorry just curious, so there would be a 1% chance I conceived on XXXXXXX 18?

Answered by Dr. Jay Patel (10 minutes later)

Brief Answer:
It may be a rare possibility

Detailed Answer:
Hi,

Welcome back, it may be a rare possibility. Miracle does occurs so, yes it can be possible in 1% on cases.

Thanks again.
Dr XXXXXXX XXXXXXX

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Jay Patel (4 minutes later)

Ok I am just having trouble understanding how my ultrasounds could be off a month & I used protection & I had bleeding. I dont understand how it is even a possibility.

Answered by Dr. Jay Patel (23 minutes later)

Brief Answer:
Some times things do not work as planned.

Detailed Answer:
Hi,

Not every things are certain but in your case you are pregnant and ultrasound does show the evidence of fetal life present in you.

Now rather then understanding how and why it happened will not change the present. Sometimes things happens and no explanation will satisfy a person.

Sometimes the bleeding from Plan-B medication may not have expelled the embryo and it may have stayed stuck in uterus and that happens in 1% of cases and it may be your case.

Sometimes the fetal growth may be faster then expected (macrosomia- larger body), its seen in babies born from diabetic mother and growth may deceive the date of development.

So many possibilities are their.

Hope it helps to explain some other things.
Thanks again.
Dr XXXXXXX XXXXXXX

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Jay Patel (1 minute later)

Ok, but would you say this is in the case in my situation? I'm sorry I am just confused.

Answered by Dr. Jay Patel (12 minutes later)

Brief Answer:
Only 1% Chances of being conceived in XXXXXXX

Detailed Answer:
Hi,

Sorry here is what i meant to say.

ONLY 1% Chance of being conceived in XXXXXXX Still 99% chance is being conceived in mid feb.

Looking at the evidences you provided that you took PLAN-B in XXXXXXX and did had withdrawal bleeding reduces the chances to only 1% of you been conceived in XXXXXXX

If you need further confirmation DNA/ genetic testing will help to check who fathered the baby.

Thanks again. As usual feel free to contact if still further clarification is needed.
Dr XXXXXXX XXXXXXX

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar