- non fasting blood test at woman's 10 week of pregnancy and an obstetric ultrasound at the woman's 12 week
- Women need to understand that the test is only a risk assessment. It places their pregnancy in an increased or decreased risk category.
- First trimester antenatal screening mainly looks for 3 conditions: down syndrome, edward syndrome and open neural tube defects.
- The woman needs to understand that screening only tests for certain chromosomal abnormalities and does not guarantee them a normal child.
- A diagnostic test either an amniocentesis or chorionic villus sampling need to confirm the diagnosis
- For first trimester screening, the blood is analysed for 2 biochemical markers (fbhCG and PAPP-A) for down syndrome. The 12 weeks U/S allows measurement of the nuchal translucency and osscification of the nasal bone.
- Key information for the 10 week blood specimen
- patient's date of birth
- weight
- her ethnicity
- diabetic or not
- the date of her last normal menstrual period
- her estimated date of delivery
- any previous pregnancies have been affected by down syndrome
- twin pregnancy?
- pregnancy achieved via IVF and if an egg donor was used, if yes, the age of the donor (if known)
- First trimester screening has a detection rate of 95% and a screen positive rate of 2.5. This means that of 10 000 women tested, about 250 will have an increased risk for down syndrome, 19 have an affected pregnancy and one affected pregnancy will be missed.
- It is not a free test. There will be an out of pocket expense of $ 100 for patients unless they are referred from a hospital
References:
- http://www.racgp.org.au/download/documents/AFP/2011/October/201110bonacquisto.pdf
- http://www.vcgs.org.au/pathology/downloads/mss/MSS-O-235_LMS_Alpha_DS_risk_calc.pdf
- http://www.vcgs.org.au/pathology/downloads/mss/BG-W-218_Charging_Policy.pdf
No comments:
Post a Comment