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Doppler U/S - How accurate?
by confuzedpartner, Sep 21, 2009 02:36PM
This may be a case for paternity. I need some help in calculating the exact or close enough date of conception.
Here are some important details surrounding the pregnancy:
LMP was unkown and was calculated based only on the Doppler Ultrasound scan. Mother had irregular cycles and did not have periods for 3 to 4 months
Home pregnancy kit reported negative for pregnancy between 22 Nov 2008 and sometime in week of 20 Dec 2008
The date of first intercourse was 22 Nov 2008.
The date of second intercourse was around 20 Dec 2008
The date of third intercourse was around 1 Jan 2009 to 6 Jan 2009 or around that time
Ultrasound on 3 Feb 2009, and learned of her pregnancy.
Ultrasound dating was 6 Weeks 3 Days.
Here are some more details of her ultrasound,
Mean Sac diameter of 20mm is 6 Weeks 3 Days
Fetal pole and Yolk sac noticed
CRL measures 6mm corresponding to 6 Weeks 4 Days
Heart rate measures 150 beats per minute
Cervical length measures 40mm
EDD as per ultrasound is 26 Sep 2009
Impression: Single live intrauterine gestation of an average of 6 Weeks 2 Days
A beta thallasemia test done during the 11th week did not indicate any maternal contamination.
Baby delivered on 09 Sep 2009.
Question #1- What would be the likely date of conception?
Question #2- What is the likely date of first day of the LMP?
Question #3- Can this pregnancy result due to having intercourse on 22 Nov 2008?
Question #4- Is it possible for the ultrasound to underestimate gestational age by 4 or more weeks?
Question #5- How accurate is doppler ultrasound, and what are the possible sources of errors?
Question #6- Does a beta thalassemia DNA analysis detect non-paternity cases?
Question #7- What are the chances that this could be a case for non-paternity?
Thank you very much for taking the time to read this letter.
Looking forward to your reply
Here are some important details surrounding the pregnancy:
LMP was unkown and was calculated based only on the Doppler Ultrasound scan. Mother had irregular cycles and did not have periods for 3 to 4 months
Home pregnancy kit reported negative for pregnancy between 22 Nov 2008 and sometime in week of 20 Dec 2008
The date of first intercourse was 22 Nov 2008.
The date of second intercourse was around 20 Dec 2008
The date of third intercourse was around 1 Jan 2009 to 6 Jan 2009 or around that time
Ultrasound on 3 Feb 2009, and learned of her pregnancy.
Ultrasound dating was 6 Weeks 3 Days.
Here are some more details of her ultrasound,
Mean Sac diameter of 20mm is 6 Weeks 3 Days
Fetal pole and Yolk sac noticed
CRL measures 6mm corresponding to 6 Weeks 4 Days
Heart rate measures 150 beats per minute
Cervical length measures 40mm
EDD as per ultrasound is 26 Sep 2009
Impression: Single live intrauterine gestation of an average of 6 Weeks 2 Days
A beta thallasemia test done during the 11th week did not indicate any maternal contamination.
Baby delivered on 09 Sep 2009.
Question #1- What would be the likely date of conception?
Question #2- What is the likely date of first day of the LMP?
Question #3- Can this pregnancy result due to having intercourse on 22 Nov 2008?
Question #4- Is it possible for the ultrasound to underestimate gestational age by 4 or more weeks?
Question #5- How accurate is doppler ultrasound, and what are the possible sources of errors?
Question #6- Does a beta thalassemia DNA analysis detect non-paternity cases?
Question #7- What are the chances that this could be a case for non-paternity?
Thank you very much for taking the time to read this letter.
Looking forward to your reply
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It is not usual at all for an ultrasound to be off by as much as 4 weeks. (If you had asked about 1 week's difference, that is possible.) The later in the pregnancy the ultrasound is done, the less sure it is for purposes of dating.
There are a lot of pregnancy calculators online in which you can key in the date of September 9, 2009 and ask when likely conception was, given that (and this is a big "if") the baby is/was full term. Just google "pregnancy calculator" or "conception calculator." What is the mother saying about whether the baby was early, on time, or late?
I don't know if beta thalassemia DNA analysis is the same kind of analysis done to determine paternity, sorry.
BTW, this incident was when I lost my virginity and I did not even penentrate or ejaculate - but still, I am assuming even with the outside chance that I did do so for a brief few seconds, what could the possibilities of it being successful be?
The reason the paternity issue was suggested is because the mother felt that the baby has some semblance to my looks since last week or so. Can that be a good enough reason so early in to suspect paternity, when medical data from U/S scans shows otherwise?
I checked on a pregnancy calculator for Sep 09 2009 and EDD of Sep 26 2009, the dates of conception reported were around Dec 17 2008 and around January 3rd 2009.
The questions in mind are,
1. When an ultrasound gives an EDD as 26 Sep and baby is delivered on 9 Sep is that normal, it considered full term or normal? Is there an error in the EDD by U/S? I was told the baby was delivered at 37 weeks and 4 days or so.
2. Most doctors and material I have read, say the CRL measurements in early stages of pregnancy (6-8 weeks) and the first trimester are most accurrate and EDD is off by only +/- 4 days or so. Having said this, and coupled with the fact an additional scan at a different lab (done at the same time) also pointing to the same EDD, how likely is the pregnancy be due to the Nov 22 incident?
3. Assuming the fertile period is in the worst case between Nov 22 2008 plus or minus a week and there was conception, then accordingly, the U/S should calculate the age of gestation as around 11 weeks or close to 12 weeks worst case. It did not and it showed 6 weeks and 3 days. So can ultrasounds go way this way off? A week in a pregnancy though a small time fram is a long period for feotus to grow and change - correct?
4. If LMP started around Nov 22 2008, then I can safely assume that conception cannot have happened during this time and if it happened later the motile sperms can stay alive atmost for 5 days and it would not be possible for fertilization to have occured. Is my understanding correct?. Factoring even a week from Nov 22, is there any chance at all that conception could have happened between Nov 22 2008 and Nov 30 2008?
In summary what is the confidence level that I have to take the paternity test and hope that it did not occur on Nov 22 2008 onwards. Can I be confident with all the evidence I have at hand?
Please bear with me for a couple of posts more, your responses help soothe my frayed nerves and a mind that is freaking out now!
If her due date based on an ultrasound in the 6th week was September 26th, conception could have occurred the first week of January. It certainly sounds like November 22 is too early, but not December 20th or the first week of January.
You do know that pregnancy is counted medically from a (presumed) first day of last menstrual period, right? (Not a presumed date of conception.) So when the ultrasound technician said she was "6 weeks x days pregnant," that would mean "6 weeks x days from the first day of the last period." (It would not mean "6 weeks x days from conception." Conception would be presumed to be about "4 weeks x days" from the date of the ultrasound.)
Anyway, either the December date or the January date would be likely for conception of this pregnancy, with the January date seeming more likely. If that was you, you definitely should be taking a DNA test.
Yes, The November 22 date is the date I had relations with her. I did not have relations on the later dates in December and January. Why do you say conception "could" have happened in the first week of January? Is that mathematical calculation or just a likely prediction?
Indeed I do know that pregancy is calculated from first day of LMP. Which means the LMP was somewhere around the 20 Dec or a little earlier for a conception in January assuming that it is a regular cycle.
However, she says she never had a regular cycle and realised that she is pregnant when she did a home test, hence was unable to calculate the LMP.
Two days later on 3 Feb 2009 when the ultrasound dating was done it showed pregnancy age as 6 Weeks and 3 Days.
So irrespective of the Jan or Dec dates, is it safe to assume that from 22 Nov 2008, conception would definitely need to happen within a week - by 29 Nov 2008, as sperms stay alive only for around 5 days and even taking 8 days, is this calculation correct that she did not conceive due to the 22 Nov incident?
If I go by that logic then needlessly, the age of pregnancy for the ultrasound done in Feb would easily be greater than 11 weeks at the least?
Just trying to feel confident and comfortable that with this data my paternity test will exclude me.
What do you think of my analysis?
Thank you so very much once again bearing through this and giving me a rational approach to thinking. Deeply appreicate it. I look forward to your response.
I had lmp on 11/26, sex on 12/9 and 12/10 edd was 9/2, delivered on 8/31. since she delivered on 9/8, push it all up a week or so and you would have your 12/20.
I also did not know when my lmp was and they guessed my due date with in two days at 7 weeks and got it right on at 8 weeks! they are pretty accurate.
Thanks a lot. I felt so too. You have been tremendous help and I cannot say enough how much your analysis makes me feel better already.
In fact the only sexual relation was Nov 22, (it hardly was intercourse). I am being pressed to take the DNA test in about 15 days or so. What should I do in preperation for this? Should I seek legal counsel?
Apologies for repeating many facts below but I just wanted to your view on some niggling areas of concern.
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Niggling area of concern:
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I am intrigued by the fact that she had no menstrual cycle since 3 to 4 months till the time she decided to take the home test (posted above). She claims that that her last period was four months ago and she always needed medicines to induce her periods.
Can this happen? And, if it is indeed the case and you cannot calculate the LMP then does the pregnancy dating by the scan still hold true?
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End
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A couple more questions, :-)
Should I verify the authenticity or correctness of these reports with another Gyanecologist/Obstetrician/Ultrasound technecian to check if the dating was in line? Or, will the ultrasound not differ in its reading?
I am guessing, the ultrasound will not differ or depend on the LMP, it would go with foetal growth and readings noted. Thus, the 6 Weeks and 2 Days aging of pregnacy would still tie down to the December or January conception dates. Right?
Please tell me if this would change the dating or the conception dates? Anything that is a matter of concern now?
As before, I must say what a reassurance it is to wait for your reply. I look forward to it as always.
If an early ultrasound is done (the one that dated the pregnancy at 6 weeks plus is perfectly timed for this purpose), it can generally be relied on to be accurate almost to the day. Embryos that early are all so close to the same size (practically down to the millimeter) that the size at that point can be used for determining the age of the embryo and dating the pregnancy. This does not always hold true for later ultrasounds, since babies grow at different rates, and it would be a little rash for someone to assume paternity just from ultrasound evidence, since DNA testing is available. But early ultrasounds are not known to be off by very much.
Doctors base their date estimates on what they are seeing on the scan, not by what the mother says. From the embryo's size, they go backward and infer the estimated "Day 1" of pregnancy and go forward and name an estimated due date, which they obviously did. Given that they named September 26 as the estimated due date, in fact the probable conception date was in the first week of January. This is true even if the baby was born a bit earlier than its due date; babies do sometimes come early!
Don't trouble another sonographer or ob-gyn, the scan is on your side. Are you saying you think everyone made a whole bunch of mistakes on estimating the due date and the baby was in fact born on time? Even so, that doesn't take us back to November 22. Just try to stay calm. Nothing is going to change reality .. the DNA test will reveal who the father is, which is exactly as it should be. It's either your baby or it is not, and it sounds like it is not, but if it is, of course you are not going to shirk your responsibilities.
It frankly sounds like the mother has been very honest with you about her sexual activity, which she would not do if she was trying to trap you. So in your position, (unless you are so famous, wealthy or celebrated that you are a matrimonial prize), I would only retain legal counsel if the test says you are the father. If it does, I would then retain counsel for sure, and first request another test, with the lawyer being sure the test was properly handled and the lab was correctly certified and the notification process was tamper-proof. There is nothing wrong with requesting a second test if the results name you as the father, since the dates make it so unlikely, that it really would be a genuine surprise. Nobody's goal (including yours) should be to manipulate the test -- everyone involved has a vested interest in knowing the truth. Especially, a father has a moral obligation to his child and the child deserves to know who his or her father is.
Your best posture is not panic and foot-dragging, but cooperativeness and an interest in getting the testing over and putting the incident behind you. (Incidentally, the mother was being a little fanciful in saying so early that the baby looks like you. Even if it was your baby, all infants look like Mister Magoo or Winston Churchill. Write it off to the hormones of early motherhood, and let it flow past without worrying you.)
I guess I do not have to add that condoms are a great invention and very good for peace of mind in all circumstances. I am sure you will be a very good father, and would never dream of shirking your responsibility to any child you helped to put onto this earth. But it should be at a time of your choosing.
Stay healthy,
AnnieBrooke
You are patience epitomized! Are you a counsellor or medical professional?
I wonder if anyone else would have answered this in earnest and objectivity.
Paternity issues are a stigma here in India, and there are no forums to openly discuss these. Private labarotories conducting paternity tests are not accepted as evidence in court of law. DNA testing is still a federal/government area and can be done only by law in authorized laborotories. For example, http://www.cdfd.org.in, conduct paternity testing only under a court order.
I won't trouble another medical professional to run my reports but like you said looks like the scan is on my side. So I will have to look at other options of paternity testing. Probably an international agency will help in doing it.
The mother has been honest with me till now but ever since she threw me this curve ball called "paternity test", I have been dreading the "what if" result and been jogging down memory lane (like an F1 car doing laps in a grand prix), trying to see some semblance of hope and rationality in "not having done the deed" lap after lap.
BTW, do you know any specific calculators with a great accuracy in dating?
What do you think of the calculators on,
http://www.redbabybook.com
http://babymed.com/Tools/Pregnancy/Conception_Date/Default.aspx, and
http://babymed.com/Tools/Ultrasound/
Once more many thanks for the HUGE support and time spent on this.
I will keep you posted as things progress. Wish me good luck and I hope not to trouble you longer with my queries!
Cheers!
Even if a DNA lab's results are inadmissible in court, if it is just for the purposes of knowing who is the father, it seems as though the three men could be tested at any reputable lab. For appropriate evidence to argue a paternity lawsuit, you would need to go to a lab that does DNA tests for the court, because you would need the results to be admissible in court. But if she just needs to know, and if all three men are willing to get tested, any lab whose results are reliable should be acceptable for that purpose. The legal niceties in India being what they are, I would talk to a lawyer about that issue. The only caveat I would add is that if you are not going to go through the officially sanctioned lab, you should accept being tested only if the other two men are also being tested. All three men should be tested at once, unless the lab is the official one and can absolutely be trusted and its results can be enforced.
Your main approach should remain that you are willing to be tested. The person who does not want to be tested and has to be forced by court order to do it, is the one onto whom the finger of suspicion will fall. You feel sure this baby is not yours, so your position should be one of "My conscience is clear, test me and get me out of this awkward situation."
Just some other options I was thinking about..
I was just wondering if I got my blood grouping done once again to see if my genotype is AA or AO and then look at my RH factor, I can surely derive if my alleles were passed on to the child.
If I am genotype AA and knowing that the blood group/phenotype of the mother is O+ve and that of the child is also O+ve then both their alleles would have to be OO with an RH factor +ve.
If the child had to inherit OO alleles from the parents, one allele from the mother, must be O, and the other O allele has to be donated by the father which means that the father must either have an OO or AO or BO genotype/allele. The father cannot be with an AA allele, thereby safely excluding any A +ve blood group with allele AA!!
(The only A, B phenotype combinations that does not result in an O blood group in the offspring are ones that have AA and BB alleles from the father. Because if it was so then the child would either be of the blood group A+ve or B+ve and not O+ve. It is also known that A and B alleles are dominant over the recessive O allele)
If I am able to work this out and couple it with the scan dating, is a paternity test still necessary to take?
Of course, this is theoretical but it still would work in principle and give me a fair degree of confidence and comfort for exclusion if I am (AA)/A+ve blood type.
I have asked for an opinion in the Genetics forum too - waiting to hear from them.
I am back :-(
I realized it doesnt work the way I thought it would.
I was unable to progress further than subgrouping my blood to the next level which is A1 RH +ve type. Nothing more, so I cannot make out my genotype composition from this. I guess the only way it can be is via a DNA profiling and costs as much as the paternity test.
So even if I do it and it turns out my genotype is A101,A101 or A101,A102 - basically an AA genotype, then I will be at peace but if not I really have to just go with the scan report and the dating that has been done based on size and measurements.
Do you think it it worth getting a DNA profiling done for myself?
Take care!
The only part of the picture I do not know much about is whether there is really a stigma attached to having a DNA test for paternity. I think it's unlikely that there would be more stigma attached to testing for paternity than there would be about fathering a child when unmarried.
In your shoes, I would stop trying to get out of the paternity test, you would risk seeming like you sneaked out of it with some confusing mumbo-jumbo about blood type, and the same people who would stigmatize taking a DNA test to clear up the paternity question will wonder why you didn't just take the paternity test and make everything clear that you are not the father.
It sounds from the website you linked on here that they need the blood to be drawn in a court setting so all the links in the chain of custody of the samples will be beyond reproach, not because you are dragged in under arrest or anything. I would stop sweating it and trust that the dates make it clear you are the least likely candidate to be the father, and go get the test.
Would I need to add two more weeks to the this? That would take the age of pregnancy to 8 weeks now! Pushing it by two weeks from December 20 would bump it up to December 9th as the LMP, so isnt it getting closer to the November 22nd date? And, if it is so could irregular cycles or a long cyle make my chances much slimmer?
I am so muddled up with all these terms, I am just going by the reading from the scan which measures CRL at 6mm and puts it at 6 weeks and 4 days. Whether this is 6 Weeks and 4 days from LMP or from the date of conception.
Just am a total nervous wreck today, no idea how to verify this?
Hope 6 weeks 2 days is the age from the first day of the LMP and that is what is meant by the gestational age and not the conception age.
You can order this DNA test by mail, and you'll know very soon. All you need is a swab from your mouth, and a swab from the baby, you send it in to the lab, and get results onlilne.
It wouldn't be acceptable in an Indian court of law, but it would give you the correct answer.
Maybe you could talk to her about that and see if she would agree.
https://www.homedna.com/paternity_test.html
Confused about the calculation from U/S dating, whethere gestation age is calculated from 1st day of LMP or if it is the actual conception age. If it is actual conception age then I need to add 2 weeks.
I am sure Annie answered it correctly earlier, but I am waiting to hear from her on this again !
Thanks for pitching in.
"In the beginning...": Determining Gestational Age and Due Date
===============================================
Monday, August 28, 2006
Kenneth F. Trofatter, Jr., MD, PhD
=========================
The other day, I repeated a conversation I have had countless times. I was finishing up an early ultrasound on a very young woman and informed her that she was 8 weeks’ pregnant and congratulated her on coming in early for prenatal care. At that point her also very young boyfriend glared at me and at her and she burst into tears saying, “I can’t be 8 weeks pregnant. I only had sex 6 weeks ago and that was the first time in my life.” “That’s perfect,” I replied, “In obstetrics, the way we figure things, you are considered to be two weeks pregnant the day you conceived, so you probably got pregnant just when you thought.”
From the looks of disbelief and mistrust, I knew they didn’t understand, so I went on to explain. When women have regular menstrual cycles every 28 days, they usually ovulate (hatch an egg)around day 14 (counting from the first day of the last period). Once they ovulate, they have only about 24 hours that the egg can be fertilized and fertilization actually occurs in the fallopian tube. Over the next 3-4 days, the fertilized egg divides several times as it travels down the tube to an implantation site within the uterus. Since most women have fairly regular menstrual cycles, and long before we knew when conception actually occurs, the tradition was begun that the due date was calculated from the beginning of the last period. "Thus, as I was saying, you are two weeks’ pregnant the day you got pregnant. It’s a tradition we have continued for convenience and for the confusion of our patients."
From the first day of the last period in women who have regular periods, the due date is approximately 280 days, corresponding to 40 weeks. This can be estimated by counting 9 calendar months from the first day of the period and adding 7 days. Alternatively, you can pick up a pregnancy “wheel” or use an online “calculator.” Today, estimates of gestational age by ultrasound are generally accurate within 3-5 days in the first trimester of pregnancy, within 10-14 days in second trimester, and become much less reliable (no better than +/- 2-3 weeks) after that. Prior to ultrasound, we confirmed gestational age by the time of "quickening" (the first perception of fetal movement by the mother) and the first detection of the fetal heart tones by a special stethoscope (a fetoscope), both of which generally occur at about 18-20 weeks. Pregnancy dating is important because we use it to schedule certain laboratory studies (e.g., serum screening for neural tube defects and chromosomal abnormalities; screening for diabetes) that can only be interpreted reliably if the “dates” are known. We also depend on accurate dating to schedule fetal testing in women at risk for complications and for elective deliveries by cesarean section or induction of labor.
“So,” I said, “we now know how pregnant you are and as a result we now have a firm due date that will not change, even if the baby is bigger or smaller on follow-up studies.” Her only response was “Doctor, so how many months does that make me?” I could only sigh...."Lunar months or calendar months?" I asked.
Going by this, if delivery did happen in the 38th week @ 37 W and 4 days, then would you be able to predict one's LMP and verify the date of conception? Will this tally with the conception date we calculate based on the measurements taken in the U/S?
If first trimester I am to understand that a scan is pretty accurate, then CRL and MSD measurements must not be off by 5 to 7 days, right?
So how did delivery happen earlier by 2 weeks? Did not the CRL measurements not predict the correct EDD or was the irregular cycles shorter? If so how much shorter?
Just wondering if these variables would explain early delivery or the error magins (was there one?) in the U/S scans?
Hope you had a good weekend and got the washinng machine problems sorted out!
Nothing about the periods' length affects the length of pregnancy. Once a woman is pregnant, whether her menstrual cycles were short, long, or even absent before the pregnancy affects nothing. (Even women who have IVF past menopause and have a baby still have pregnancies counted the usual way.)
RockRose gave you good advice, which you should not turn away lightly -- if the mother is amenable to just doing one of those cheek-swab tests, do it. If you point out to her that all the dates suggest you could not be the father and then suggest this route, she might be open to it. But if she insists on one of the tests that is official enough to hold up in the Indian courts, go, do it and forget the whole issue. Dredging up esoteric theories will not change reality. A baby who needs to know who its father is, and everyone involved needs to know too.
Many websites for paternity testing have debated on the accuracy of ultrasounds in determining the conception date for paternity.
Most of them state -
"...Ultrasound dating of conception is not reliable for determining paternity UNLESS the encounters in question are at least two weeks apart..."
"...If you are seeking the estimated date of conception for paternity reasons, and intercourse with two different partners took place within 10 days of each other, we strongly encourage that paternity testing be done..."
I was looking at my case purely from what most DNA testing sites cited and was wondering if this warranted a paternity test in my case.
So, would an encounter of a month (or four weeks apart) require a need for paternity testing?
Just asking this question because the odds or the statistical probability of the conception dates do not make it a compelling reason to take one, as intercourse was not within the 2 weeks or 10 days window of each other.
Can I strongly believe in the odds will be in my favor even if I do take the test?
Confuzed, you are wasting a lot of energy with your research and guesswork, when a simple test will give you the answer with certainty.
Stigma or not, cost or not, take a paternity test and you will have your answer. I'm sorry that there is no other way to be 100% sure.
Come back when you have the information to share, and let us know what happened. Good luck!