When we got bad news after our NT scan I found it very hard to find any information on this topic. I hope that my findings will help people to feel more informed on their options and choices. I'm not a medical professional myself so I may be very wrong with some info or conclusions. Also I'm pretty sure that actual doctors can give you most accurate info for your particular case and you may not have some options depending on individual cases.
When you have a high NT measurements (over 3.5mm) it may be a sign of either genetic abnormality or heart problems. To investigate further into genetic abnormalities you have 3 options:
Harmony blood test
Positives: non-invasive, so no risk of miscarriage
Negative: will cost you lots of money ($400-900 I got different estimate prices at different places), this is not a diagnostic test, but it will recalculate your risk many times more accurate than NT scan
Overall: it's good if your results are borderline and you not sure if you want diagnostic tests
Positives: will give you certain results on most common genetic problems, can be performed earlier (before 14 weeks), bulk billed when done at the public hospital
Negatives: official stats have 1% of miscarriage risk, procedure is a bit uncomfortable
Overall: good option if you want to know for sure and if you can't wait long especially if your results are high (over 4mm). Sometimes this option is not available if your placenta is in bad position or if your placenta is not functioning well (based on one of the blood results that you have done for NT scan)
Positives: will give you certain results on most common genetic problems, less miscarriage risk than CVS (0.5%), bulk billed when done at the public hospital
Negatives: still has a miscarriage risk (0.5%), can only be performed after 14 weeks and most hospitals prefer to wait until 15,5 weeks.
Overall: seems like the less risky option if you want to know for sure. Gives you time before the test to think and make sure that you want it.
The main question I had is why women choose to have CVS if Amnio has much lower chances of miscarriage. I have found following info that helped me to decide:
- The wait to be 15,5 weeks to do amnio sometimes just too long (considering that your NT was performed around 12 weeks)
- Statistics for miscarriage for general population is as high as 0,5% when you are under 14 weeks which sort of bring down increase in risk of the actual CVS procedure to 0,5%. Stats for general miscarriage after 14 weeks is very low (couldn't find actual data) so the increased risk of amnio is still probably about 0,4%. This info made both procedures almost equally risky in my mind.
- if you know that you will want to terminate your pregnancy if your baby has genetic abnormality you will want to know that if you are under 16 weeks you will prob have a procedure to clean out your uterus under general anesthetic. If you are over 16 weeks you most likely be induced into early labour. That was a big deal for myself as it leaves very small window after Amnio and if you are waiting for full results of the test that may take about 2 weeks you are def over 16 weeks.
I've decided to go with CVS as Harmony test is not diagnostic and I couldn't wait another 3 weeks for amnio results and didn't want to be induced in worst case scenario. I've just had it today, it was a bit uncomfortable but not too bad. Now I'm waiting for good results and hopefully no miscarriage.
To investigate into heart problems and other structural abnormalities they just do very detailed ultrasound at 18-20 weeks and potentially extra early scan around 16 weeks. I'll have mine booked at Fetal Medicine Unit at hospital after we'll get results of our CVS.
Now the good news is that if you will have a good CVS/Amnio results and a good Ultrasound at 20 weeks and won't miscarry until 20 weeks than your risk of having any problems with your baby drops back to the same level as general population. So you can forget about your bad NT scan and enjoy your pregnancy.
This is the start of long 7 weeks for myself (to be 20 weeks), but we are hopeful that everything will be fine.