I did it over 2 years ago when I had placenta abruption and I was 3-4mm diluted. The doctor said that she needed to do an amnio to see if my baby's lungs were developed before she would induce labor.
The needle was very long and thin. I had 3 doctors in the room to do this for me, 1 senior to supervisor, 1 actually did the amnio and 1 watched the u/s. The 3 discussed how to do and where to stuck the needle in and what degree of the needle should go. It did not take too long and it's not that scary. I and my husband do not scare of needle or blood and we just worried about the test result. Luckily, the analysis came in 2 hours and finally the doctor induced labor.
But, there's also a risk on amniocentesis. My sister in law leaked water afterwards and finally needed to go for bedrest for 6 weeks. Of course, it may not be due to amnio and everybody's different.
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