[originally posted to Facebook Tuesday, January 25, 2011 at 9:56am]
Well, today is a "special" day as my son would say. Today is the ultrasound in the high risk clinic where we scan my little Wyatt for any and all "soft" markers for chromosonal problems. These clues are known as soft simply because their presence isn't diagnostic, but rather potentially indicative at best. There are also a lot of ratios and probabilities to consider. To be honest, the math makes my head hurt.
Trisomy 18 known as Edward's Syndrome. It has a very low survival rate. http://en.wikipedia.org/wiki/Trisomy_18 .
Trisomy 13 is also known as Patau Syndrome. It also has a very low survival rate. http://en.wikipedia.org/wiki/Patau_syndrome .
Quite a few of you have asked what some of the markers are, and I will do my best to provide an answer, if not a link that explains it clearer and more concisely than I would. So, saddle up and get yer learn on.
These markers are generally used early for screening purposes:
Basically a mineral deposit in the heart that may or may not appear bone like. 88% are only in the left ventricle, 5% are only in the right, and 7% are biventricular. It is suggested by current research that the biventricular, right sided, and generally less popular types are more indicative of chromosonal abnormality
Dilation of the kidney where the ureter meets it. This can happen on it's own, however in the presence of other markers, it become significant.
SINGLE UMBILICAL ARTERY
There are supposed to be two arteries and one vein in the umbilical cord; the arteries take away the deoxygenated blood from the baby to the placenta. Alone, it is not indicative of chromosonal defects, yet it has been associated with renal and cardiac problems. Together with other markers, it increases the risk of finding a chromosonal problem.
This is the fetus' bowel showing up as bright as bone on the ultrasound. Alone, it has been associated with cystic fibrosis, infection, bowl malformation, intra-amniotic bleeding and intra-uterine growth retardation. Together wih other markers, it shows an increased risk for Trisomies 13, 18, and 21.
THICKENED NUCHAL FOLD
Here we are with our friend the nuchal transparency again. Since this is done earlier in the pregnancy, I don't think it will be looked at today. One more thing of note: it was explained to me by a nurse very much in the know that since Wyatt and Zoe's were done much earlier than Quinn's, the results are a little more significant (ie: larger numbers on a smaller baby). Alone, it can also be indicative of congenital heart defects (which we knowWyatt has already), or it can be a flag for Down's. There has also been associations with other abnormalities that are not chromosonal in nature (ie: skeletal, etc).
Dilation of the ventricles in the brain. Does occur on it's own, but incidence with Down's Syndrome (Trisomy 21) is very much increased. Can resolve on it's own as well, although unlikely.
CHOROID PLEXUS CYSTS
Found on ultrasound between 14 and 24 weeks gestation. 50% of fetuses that have this have Trisomy 18; inversely 10% of those with Trisomy 18 will have this as the only marker. As far as I know, this has not been identified in our case.
ENLARGED CISTERNA MAGNA
This part of the brain collects cerebral spinal fluid. When dilated without the presence of ventriculomegality (but with the presence of other markers) it is indicative of Trisomy 18. It is also rarely seen in the presence of other, non chromosonal disorders.
These markers are very useful in later comprehensive ultrasound (that I will be having today):
SHORT FEMUR LENGTH
Useful in predicting Down's Syndrome. Also occurs with situations such as Fetal Growth Retardation.
SHORT HUMERUS LENGTH
See short femur length.
Absent or short nasal bones increase the risk of a Trisomy 21 finding.
A bending or kink in the fifth or "pinkie" finger towards the rest of the fingers. This is found in 60% of people with Downs. However, it can be found isolated in the general population as well.
Basically the foot looks like a rocker on a rocking chair. This is generally found with Trisomies 13 and 18.
These markers that have NOT been established for practice (due to lack of research, mainly) but might be useful:
A flattening of the head. Unreliable as there isn't enough variance between "normal" and Trisomy 21. More research is needed as there may be a link for Trisomy 18.
INCREASED ILIAC ANGLE
It has been noted that there appears to be an increased incidence in flared iliac bones in Trisomy 21. More research is needed in the general population.
SMALL EAR LENGTH
Infants with chromosonal abnormalities generally have small, low set ears. It's a bit tricky to see on an ultrasound, but ear length can be seen occasionally.
This is a separation of the big toe and the next (as flip flops or thong sandals would do to your foot). 45% of children with Trisomy 21 (Downs) have this although the statistics vary. It is also unsure whether this occurs in the regular, non chromosonally abnormal population.
Other findings that we (thankfully!) have not run across:
A protrusion of intestines, liver, etc OUTSIDE of the fetus' body. Occurs with Trisomy 13 and 18.
Can occur with or without genetic involvement.
Extra fingers and/or toes.
And there are more, such as clubfoot, overlapping fingers, clenched fists, etc, etc, etc. I unfortunately do not have the statistics on these.
Whew! That's a lot to absorb and I hope it helped. I hope the ultrasound brings us a little piece of mind as well as this is the stuff that keeps me awake at night. Once again, it doesn't always pay to be a nurse...
As a good friend of mine pointed out the other day "hang on to hope... that's what it's there for".
Trust me, we plan to.