antenatal and postnatal screening

• Antenatal and postnatal screening is when a variety of techniques are used to monitor the health of the mother, developing foetus and baby.
• Pregnant women are given two ultrasound scans.

  • Dating scan – takes place between 8 and 14 weeks. It determines the stage of pregnancy and due date. This is used with tests for marker chemicals which vary normally during pregnancy.
  • Anomaly scan – takes place between 18-20 weeks and may detect serious physical abnormalities in the foetus.
• • Routine blood and urine tests are carried out to monitor the concentrations of marker chemicals.
  • Measuring a chemical at the wrong time could lead to a false positive result.
  • An atypical chemical concentration can lead to further diagnostic testing to determine if the foetus has a medical condition.
• • Amniocentesis is a procedure is usually carried out between the 15th and 20th week of pregnancy which involves the collection of foetal cells contained within amniotic fluid.
  • A needle is inserted through the abdomen/uterus wall into the amniotic sac and a sample of the amniotic fluid is collected.
• Amniocentesis:

  • Advantage – it is used to detect genetic or chromosomal abnormalities of the foetus.
  • Disadvantage - the procedure carries a risk of miscarriage.
• • Chorionic villus sampling (CVS) is procedure usually carried out between the 11th and 14th week of pregnancy.
  • This procedure removes a small sample of cells from the placenta. These can be obtained through the abdomen or through the cervix.
• CVS:

  • Advantage – it is used to detect genetic or chromosomal abnormalities of the foetus and can be performed earlier than an amniocentesis.
  • Disadvantage - the procedure carries a higher risk of miscarriage than an amniocentesis.
• Diagnostic testing:

  Cells from samples are cultured to obtain sufficient cells to produce a karyotype to diagnose a range of conditions.