20 week scan

[Tanlee]

I know that the 20 week scan picks up major structural abnormalities, and it also picks up "soft" markers aswell. I was wondering if anyone knows how accurate they are? Would it always pick up downs (ie. does downs usually have a lot of soft markers which would likely be seen)? I want to put my faith in the scan but am worried about how much they might/can miss. Any advice would be really helpful.
Thanks!

I've no info to give but at my 20 week scan they had a fact sheet with diagnosis ratings on hopefully yours will too, maybe phone in advance to see though as mine never used to.

No it is not infallible but should pick up any clusters of issues which together might indicate conditions such as Downs or any other congenital problems which can then be monitored. Ask the radiographer or your midwife .

Mine didn't use soft markers, but did check the heart and other vital organs.

Did you not have a nuchal fold measurement taken ( and blood test )at 13 weeks?

I did have the blood test and nuchal at 12 weeks. Came back with a 1/3200 low risk. Just wanted reassurance that if there were any problems they would most likely be picked up on the scan.

The only guaranteed way of picking-up Downs etc is an amnio. It is likely that abnormalities would show on the scans but not definite. A Downs baby with a healthy heart and decent growth could go undetected.

The term soft markers refers to things that are picked up on ultrasound that could be indicative of certain conditions. All 20 week scans will search for them. The thing is that you can have soft markers and a baby with no conditions but also you can have a baby who has a condition but dies nit show any soft markers. You can't diagnose from soft markers alone.

We had a couple of soft markers show up on DD1s scan she had and echochromic or echogenic bowel (where the bowel showed up white on the scan, it should usually be black; hers was as white as bone). She also showed some heart defects. The soft markers in her case pointed towards a chromasomal defect or possibly cystic fibrosis.

We were offered further tests. We had a foetal echo scan which was a detailed look at bloodflow through her heart and a more detailed anomaly scan at the regional specialist foetal medicine unit. We had the scans and although the glowing bowel was still present her heart turned out to be fine. We were then offered amniocentesis to conclusively rule in or out downs etc. We declined further testing as we wouldn't act on anything and it wouldn't change our antenatal care or impact on the birth.

So in our case we had several soft markers at 20 weeks that just turned out to be one of those things and not linked to any specific condition.

You will usually be given a leaflet or similar setting out pros and cons and limitations of each scan.

Good luck op.

My 20 week scan did not pick anything and I went on to have a child with downs. He has no heart problems so obv nothing to see there and has a lovely wee nose with a bridge, again nothing to see there. He's an average size so no short femurs. It's not a diagnostic test, just a best guess.

I had no soft markers either and had a pretty normal pregnancy too. DD was born with a blocked bowel (a complication of cystic fibrosis) and had major surgery at 3 days old removing a large part of her small intestine.

Theoretically this should / could have been picked up on the scan but wasn't. I was actually quite grateful in a way as it meant I could enjoy my pregnancy and look forward to the birth without having to spend weeks worrying on what might be.