Research into reliability of early US diagnostic scans?

[Tangle]

Not sure if I phrased the title well, but I'll try and explain.

I remember reading a thread not so long ago where a sonographer estimated that they would expect to identify just 25-35% of cases of abnormalities that can be seen on a scan (which I'm interpreting to mean as for any given condition that can, in theory, be seen on a 20 weeks scan, only 1/4 to 1/3 of babies affected will identified - if I've got that wrong, please can someone correct me!).

I guess what I'm trying to work out is whether there are any comparable statistics for an early scan? Does anyone know if there's any research in this area? How many conditions can be identified by an US at 7/8/9 weeks and how reliable are the screening results for those conditions? Does anyone know if there's any research into this area?

Thanks

[BelleDeChocolateFluffyBunny]

At 7/8/9 weeks it's possible to tell if there's multiple births, it's possible to tell if there's an eptopic pregnancy, a blighted ovum, a heartbeat and that's about it. Ultrasound is a really good tool but it's operator dependant and it's reliant on the fetus being in the right position. There probably is some research in the area, there is an obstetric and gyne journal so it's going to be in there, it's a PITA to find online though.

[MumNWLondon]

all they can tell at 7-9 weeks is:

a) whether the baby has a hearbeat
b) how many babies there are
c) an estimate of due date

They can't diagnose anything else.

[Tangle]

That's even less that I figured! Although I don't know why I'm that suprised [cynics R us]

So by the sounds of it the chances of identifying that a foetus with a heartbeat has a condition that is incompatible with life is pretty non-existent. In which case, is it fair to say that with the exception of an ectopic pregnancy, there wouldn't be any additional medical complications caused by not identifying identifying a problem before 11-13 weeks? And if there was a problem, would the recommended medical course of action be any different 4-6 weeks down the line?

[BelleDeChocolateFluffyBunny]

An anomoly scan is done at 12 weeks ish as this is the best time for the sonographer to identify the major organs and any anomolies, before this age the fetus is too small and organs are not well enough developed. I suspect that it also allows enough time for the parents to have a think about their options should the scan show up anything serious. In cases where there have been recurrent miscarriage or bleeding then they do scan earlier but they tend to just check for a heart beat and look at the placenta rather then a more indepth assessment.

[Tangle]

Here's what I'm trying to understand:

The consultant suggested that if a problem was identified and we decided to terminate then before 13 weeks it would be possible to have a D&C but once we got to 13 weeks they'd induce labour and I'd have to birth the baby instead. But from what's being said here the only problems that can be identified at, say, 8 weeks will be ones that say the pregnancy is already ended or never really began - which to my mind means the foetus isn't going to do much growing over the next few weeks. At the moment I don't see where she's coming from in suggesting an early scan would give us a choice that would be denied us a few weeks later.

(sorry - this is all getting a bit deep, but I really appreciate people taking the time to reply)

[BelleDeChocolateFluffyBunny]

It's OK. It sounds like a really stressful time for you.

A fetus grows at a rapid rate, especially in the first and second trimester, this is where the problems are. It's not always possible for a sonographer to see the organs and structure of the skull one week as they are just too small, the next week they may be visible. At a normal pregnancy at 8 weeks there's normally just a sac, a blob with a heartbeat and a yolk sac (this provides nutrients until the placenta is ready to take over). The sonographer really can't see anything else as the fetus is just too small.

this is what they can normally see, so it's really hard to make anything out at all.

[BelleDeChocolateFluffyBunny]

this is at 12 weeks so a few weeks really makes a difference, the spine can be seen, so can the chambers of the heart, even the two sides of the brain, as well as the kidneys, femurs, diaphragm and the mouth. The fetus really does grow this quickly, they can't do the scan any earlier then this to check for any problems because the organs are just too small.

[MumNWLondon]

personally i don't see any point in a scan at 6-8 weeks, even if you are bleeding as nothing they'd do about a multiple pregnancy before 12 weeks anyway, and if no heartbeat not much they can do either and nature likely to take it course shortly. perhaps its useful if you have no idea at all of dates or obviously if any additinal risk of ectopic, either as you've had one before or have any symptoms.

at 12 weeks much more can be seen including nuchal measurement, and organs also you can have a CVS which can detect any genetic problems, although still its much more basic that an anomoly scan at 20 weeks.

[Tangle]

Thanks ladies - that's pretty well what I thought. I just don't see where she's coming from at all for this!

(They're offering me an early scan as DD2 was stillborn at 8 months at the beginning of the year - absolutely nothing they'd expect to repeat and no medical reason whatsoever for anything beyond normal care. I appreciate them trying to help me avoid reliving too much of DD2's birth, but I just don't see how an early scan is going to help with that at the moment...)

Maybe I should just send her a letter and ask.