ASSESSING FETAL HEALTH

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Prenatal paediatrics/fetology

• ASSESSING FETAL HEALTH

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• 4 new techniques have revolutionized the
  diagnosis of fetal malformations and genetic
  disease
• Maternal serum screening
• Ultrasonography
• Amniocentesis
• Chorionic villus sampling

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Maternal serum screening

• 2 types
• Triple screen, quadruple screen
• Triple screen
• Alpha fetoprotein AFP
• Human chorionic gonadotrophin hCG
• Estriol
• Quadruple screen above 3 tests inhibin-A

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• Most often done in combination with
  Ultrasonography
• Tests are done at 16-18 weeks of gestation
• ?AFP levels suggest a neural tube defect
• ? hCG, inhibin-A levels suggest Down syndrome

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• Not a diagnostic test
• Indicator of possibility of some birth defects
• Inform parents about a high false rate upto
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• Other procedures should follow
• RISK unnecessary worrying by parents

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Ultrasonography

• Ultrasound beam scans inside of the body
• Computer analyses pattern of returning echoes
• Tissues of different density reflect sound
  differently
• Pattern of echoes used to decipher inner
  structure of the body
• With improved image quality, fetal structure
  visualised

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• Many malformations are visualised
• USG also used to guide needles and catheters for
  amniocentesis and Chorionic villus sampling
• 3D and 4D movies of sequential images sonograms
  provide enhanced images with good resolution

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Images B and D show fluid accumulation in back
of neck indicating presence of a congenital
anomaly
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Transabdominal Amniocentesis

• common technique for detecting genetic disorders
  (e.g., Down syndrome).
• Indications
• Advanced maternal age (38 years or older)
• Previous birth of a trisomic child (e.g., Down
  syndrome)
• Chromosome abnormality in either parent (e.g., a
  chromosome translocation)

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• Women who are carriers of X-linked recessive
  disorders (e.g., hemophilia)
• History of neural tube defects in the family
  (e.g., spina bifida cystica)
• Carriers of inborn errors of metabolism

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• Aspiration of amniotic fluid between 14-16 weeks
  of gestation
• Fluid contains metabolic byproducts fetus and
  cells sloughed from fetus and amniotic membrane

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• Tests carried out
• Measurement of alpha fetoprotein
• Fetal cell culture and karyotyping- for sex
  determination and detecting chromosomal
  aberrations
• Screening of genome for presence/absence of
  specific mutations

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Chorionic villus biopsy
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• 10-40 mg of tissue removed under ultrasound
  guidance
• Tissue directly karyotyped or karyotped after
  cell culture
• Performed in early gestation 10-12 weeks
• Yields enough tissue for molecular genetic
  analysis
• Abnormal results must be confirmed by
  amniocentesis

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• Limited value in early gestation
• Difficult to perform when volume of fluid is
  small small sample may not yield enough cells

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