ventriculomegaly
So - my wife is (just) 40, and I am 44. 2 years ago we had a m/c at ~7weeks. We went through IVF, and last summer got pregnant with twins.
At 11 weeks, both babies were fine, but when we went in for our nuchal test at 13+ weeks, one had vanished. The surviving twin looked great, however - with the blood work and no u/s anomalies found, the doc put it at 1:1650 for trisomy 21. I was a little concerned that the vanishing twin might have altered the bloodwork, but still, those are good odds.
At 16 weeks we did the quad test, which came up as 1:800 for T21. At 18w we did a level II, which was perfect, and our doc suggested the adjusted odds were probably somewhere near 1:1100. We opted against the amnio, due to the good odds and the fact that the dr suggested that the twin would not still be affecting the bloodwork, AND the scans were all perfect.
Well, my wife developed gestational diabetes, and between that and advanced maternal age, our OB put us on weekly amnio fluid index scans and non stress tests for the last few weeks of pregnancy. At 35 weeks, a tech doing the AFI noticed something odd, and measured the cerebral ventricles as being above normal - ~12mm. The radiologist said it is likely not significant, but suggested another level II u/s to rule out any additional anomalies. We went in later that week, and they did a thorough search for other associated anomalies, and found none, but verified that the lateral ventricles were 11mm. As an aside - I started asking questions based on what I had read in the medical literature (not just web surfing), and it turns out that this radiologist actually had written some of the early papers on the topic, and seems fairly expert.
So, the only other thing on u/s that concerned me (but not the doc) was that the gestational age based on femur length was measuring about 34w, we were at 35w, and the head was measuring 36w (more or less - the details are foggy now). The doc said that at this stage the error is 21 days on any pf those measurements, so those were well within normal range (I should note we are both avg sized whites, although I have a largeish head, and my father in law has short legs). He also showed that the ratios were all pretty much dead center of range - FL to head; abdominal circumference to head circ., etc (odd - I don't see how the femur length to head ratio could be dead center, when the femur measured a little short and the head a little large, but I am not a medical dr).
So, with all that background, my questions.
Much of what I read says that, when there is isolated mild ventriculomegaly (IMV), there is a 2-4% chance of T21. BUT - statistically, I can't figure out what to do with that fact, because it is not as if that eliminates the earlier scans that all came out great. Do those logically have to get ignored, since we have this finding?
Also, I would just like some input - both our OB and our radiologist say "this is likely of no concern, because it is mild and isolated, and is probably one of those things that lots of kids have but we never know, because most people don't have scans this often or this late". Still, it has scared the heck out of me (even our radiologist said "well, I realize this is probably going to ruin the rest of your pregnancy for you"). There are many seminal papers that basically say "if under 12mm, 97% develop normally", and even a couple of papers that say "10-12mm is likely just a variation on the norm", but there are ALSO review papers that paint a bleaker picture, and of course thos eare what literally keep me up at night.
Anyway I would appreciate any input,
Fish
