Obstetric dating reliability


Genetic screening for Down syndrome (trisomy 21) and trisomy 18, the national standard in the United States, is rapidly evolving away from the AFP-Quad screen for Down syndrome, done typically in the second trimester at 16–18 weeks. The newer integrated screen (formerly called for First And Second Trimester Early Results) can be done at 10 plus weeks to 13 plus weeks with an ultrasound of the fetal neck (thicker nuchal skin correlates with higher risk of Down syndrome being present) and two chemicals (analytes) PAPP-A and βHCG (pregnancy hormone level itself). It gives an accurate risk profile very early. A second blood screen at 15 to 20 weeks refines the risk more accurately. The cost is higher than an "AFP-quad" screen due to the ultrasound and second blood test, but it is quoted to have a 93% pick up rate as opposed to 88% for the standard AFP/QS. This is an evolving standard of care in the United States.


Obstetric dating reliability

Obstetric dating reliability