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Nuchal/Combined testing with Twins

(9 Posts)
SpanishLady Tue 23-Apr-13 11:47:17

Dear all - I have my 12 week scan next week and have read online about how having twins can cause the test to be flawed in so much as could come back with a high risk rating without it necessarily being the case.

Im also about to turn 39 so I am half expecting a high risk rating just on my age alone (though had my son at 36 and his rating was 1:6,400)

I guess I just wondered about other peoples experience or thoughts?


Charleymouse Tue 23-Apr-13 12:07:04

Spanishlady are you having twins?
Did you have an earlier scan to confirm this?

When pregnant with the DTs I was advised against the 16 week blood test alone. As you say it can be flawed due to the overproduction of hormone as you have two babies flooding your system.

Combined with the nuchal scan it is more accurate overall than the scan or bloods on their own.


legallyblond Tue 23-Apr-13 12:14:17

Hello! I didn't actually discover I was preg with twins until the 12 week scan (huge shock!!!)... But, I had the full, usual nuchal fold/downs screening. At my hospital (same process as hospital where I had DD 2.5 years ago in totally different region, so I expect it's country-wide) you pitch up, they do the scan inc measuring the nuchal fold, then the same day you have bloods taken. If the combined risk (nuchal
measurement plus bloods and your age) is high, you get a call in 48 hours. Otherwise, you get full results by letter in a week or so.

I was not told that twins "skew" the results, just that the results would be different for each twin (eg one could be high, one could be low) and, obviously, the chances of something being wrong are technically higher simply because you have two (the maths I guess).

Anyway, my results were 1:15,557 for twin 1 and 1:14,500 for twin 2... I am 31. Those results are broadly similar to DD (about 1:10,000 I think). The nuchal measurements were 1.5 and 1.2 mm respectively. Like I said, no mention of less accuracy, just that the results could be different.

Hope that helps!!

Ps - I am 18 weeks now...

SpanishLady Tue 23-Apr-13 12:25:54

Hi yes - I had a scan last week just to establish dates (and at this scan discovered there are two babies in there!) as I got pregnant immediately after a miscarriage without a period in between - we have worked out I must have conceived roughly 2 weeks after I miscarried (I bled for 7 days).

thank you both for your replies that has made me feel better - my DH and I feel anything under 1:500 might be worth considering more testing (depending how low it is) but anything over 500 we wouldnt investigate further.

am pretty nervous as having twins is already a shock - having babies with disabilities seems such an enormous responsibility ....

gardenpixie32 Tue 23-Apr-13 13:27:00

I also found out I was having twins at my 13 week scan. I had a Nuchal Fold scan and a blood test a couple of days later. Apparently, with twins, you need to have the scan and the blood test for the results to be accurate.

Congratulations, being a twin mum is great. My no ID girls are nearly 7 months old.

andadietcoke Tue 23-Apr-13 17:57:41

I had 'counselling' before my combined nuchal test. She went through with me how it was different with twins because they don't know for sure which twin is higher risk if it's down to the PAPP-A and beta HcG so they would have to do an amnio on both. She also talked about selective reduction and what would happen next if there was a problem. One twin had an NT measurement of 2.6 and the other 1.9. However, my scan was done at 14w. The results came back as 1 in 6,000 and 1 in 5,000 but my PAPP-A was so high they couldn't include it in the calculations so they said that the ratio should be improved. I'm 31 as well.

She told me it wasn't an option to have the measurement but not the bloods (I'd read online that some hospitals recommend this for twins) and she also said that the 16w blood test was pointless for twins.

Only other thing to note is that at my first scan they couldn't do the measurement for either twin so I had to go back. With singletons you don't get 'another go' but twins you do (at my hospital anyway).

MultipleMama Sun 28-Apr-13 00:37:54

Im expecting 2nd set of twins and had good results for my 1st set. Can't remember exactly what (it's in a baby book somewhere!) They will be different as there are 2 babies but that doesn't mean the results will be wrong or cause for concern. I wasn't aware or told that it could be flawed.

Not far a long for testing on 2nd set yet.

SpanishLady Tue 30-Apr-13 15:25:11

Hi - well had the scan and nasel bones present and measurements were Twin A 1.5 and Twin B 1.4 - Im 12 weeks 5 days along.

So now waiting for the blood work to be factored in - it was lovely to see them bouncing around!

SpanishLady Thu 09-May-13 13:47:29

thanks for all the kind responses - good luck Multiplemama and hope your scan time comes round quickly!

I have received my results:

Twin 1 risk is 1:12,000
Twin 2 risk is 1: 13,000

So wont be doing any further tests and hope all will be well! have one more week of work then 2 weeks in Spain (cant wait) - am still getting MS (14 weeks today) so hoping it will be stopping soon - nad then 20 week scan late June - am very excited to see them again and hopefully find out what we are having!!!

take care everyone

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