2 doctors weighed in:
Has any one had the blood test positive for Down syndrome but then ultrasound showed the baby fine?
2 doctors weighed in

Dr. James Ferguson
Pediatrics
In brief: Accuracy matters
The ultrasound is a screening test, and as such may over or underestimate the presence of what is being looked for. Accuracy is often dependent on the training of the tech and or who reads the study.
The blood test is a definitive test, it is either positive or not.I would never rely on the ultrasound for any decision other than pushing me to order the blood test .

In brief: Accuracy matters
The ultrasound is a screening test, and as such may over or underestimate the presence of what is being looked for. Accuracy is often dependent on the training of the tech and or who reads the study.
The blood test is a definitive test, it is either positive or not.I would never rely on the ultrasound for any decision other than pushing me to order the blood test .
Dr. James Ferguson
Dr. James Ferguson
Thank
Dr. Andrew Turrisi
Radiation Oncology
In brief: Great question.
Amniocentesis takes a fluid sample and looks at foetal chromosomes.
Down's demonstrates trisomy 21; edwards syndrome, trisomy 18. Others too. An u/s tells nothing about chromosomes, and there is not a contradiction of one test by the other. The chromsome changes are not artifacts. If you do not want to know, do not get the test. Every couple needs to make their own choice; it's no one else's.

In brief: Great question.
Amniocentesis takes a fluid sample and looks at foetal chromosomes.
Down's demonstrates trisomy 21; edwards syndrome, trisomy 18. Others too. An u/s tells nothing about chromosomes, and there is not a contradiction of one test by the other. The chromsome changes are not artifacts. If you do not want to know, do not get the test. Every couple needs to make their own choice; it's no one else's.
Dr. Andrew Turrisi
Dr. Andrew Turrisi
Thank
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