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:sunflower: Aneuploidy screening & diagnosis (:wine_glass: Screening…

- - - - Timing: GA 10-14 wks (CRL 38-45 mm)
      - Components
        
        Nuchal translucency measurement (NT) by U/S
        
        Fluid filled space measured on dorsal aspect of fetal neck
        
        Abn: > 3.0 mm
        
        Serum β-hCG
        
        Pregnancy-associated plasma protein A
    - - Timing: GA 16-18 wks
      - Components (4)
        
        Serum hCG
        
        Alpha fetoprotein (AFP)
        
        Inhibit A
        
        Unconjugated estriol
    - - Evaluate short segments of DNA in maternal blood
        primarily fr placental cells undergoing apoptosis
      - Timing: Early as 10 weeks
      - = NIPT (non-invasive prenatal testing)
      - HIGHEST DETECT rate (98%)
      - Uses
        
        Identify Aneuploidy
        
        Determine fetal sex
        
        Identify Rh-positive fetus
        
        Detect some AD genetic abnormalities
      - :money_with_wings: expensive af
- - - - Aneuploidy
      - Triploidy/Tetraploidy (3N/4N)
    - - Sickle cell anemia
      - Cystic fibrosis
      - Hemophilia
  - - - Testing of an embryo before implantation
      - Single blastomere fr a cleavage stage embryo
      - Uses only one or few cells fr early embryo ➟ Confirm with CVS or amniocentesis usu is recommended
    - - Timing: GA 10-13 wks
      - Placental villi fr Transcervical OR Transabdominal
      - :warning: performed earlier than GA 10 wks ➟ LIMB REDUCTION DEFECTS
    - - Timing: GA 15-20 wks
      - How to do:
        
        Amniotic fluid sample of 20-30 mL
        
        U/S guided
        
        :!: Avoid transplacental rupture