monitoring foetal health

• ULTRASOUND

  Uses inaudible, high frequency sound waves to produce an image of the foetus
• ULTRASOUND

  1. Probe is placed on the abdomen of the pregnant woman
  2. Sound waves are reflected by foetal tissues to obtain visual ‘echo’ of what is inside uterus 
  3. Doctor feeds reflected sounds, or echoes, into a computer to produce a screen image of the foetus for study
• ULTRASOUND

  Used to : 

  • Monitor growth and development of foetus
  • Confirm pregnancy
  • Estimate stage of pregnancy
  • Determine number of foetuses
  • Identify abnormalities of cervix / uterus
  • Determine gender
  • Evaluate anatomy of foetus
  • Genetic screening
  • Study placenta and amniotic fluid
  • Identify birth defects
  • Determine position of foetus
• ULTRASOUND

  Disadvantages : 

  • Cannot diagnose all abnormalities 
  • If abnormality is detected, further tests may be required for more specific information
• AMNIOCENTESIS

  When : 

  • Carried out between the 16-20 weeks of pregnancy

  Foetus is floating in about 130 mL of amniotic fluid
• AMNIOCENTESIS

  1. Use an ultrasound to guide a needle through the abdominal wall into the amniotic cavity
  2. Approximately 10-20 mL of the fluid is removed
  3. Living cells from the foetus are floating in the fluid, cells can be examined 
• AMNIOCENTESIS

  Used to : 

  • Detect biochemical defects 
  • Detect abnormalities in the number of chromosomes 
  • Detect abnormalities in the chromosome structure
  • Down syndrome
  • Cystic fibrosis
  • Neural tube defects (e.g. spina bifida)
  • Genetic disorders (e.g. phenylketonuria, Tay-Sachs disease, Duchenne muscular dystrophy, sickle cell disease)
• AMNIOCENTESIS

  Risks : 

  • Small risk of infection
  • Miscarriage or damage to baby

  → only performed on women who are thought to be at higher risk of delivering a child with birth defect
• CHRONIC VILLUS SAMPLING (CVS)

  When : 

  • 9-19 weeks
• CVS

  1. Obtains a specimen of foetal cells from the chorion
  2. Cells are examined in a similar way to those gained by amniocentesis
• CVS

  Used to : 

  • Detect genetic disorders
  • Detect biochemical abnormalities
• CVS

  Risks : 

  • Miscarriage following the procedure is 2% 
• CVS

  Advantages : 

  • Foetal tissue gained through CVS can be tested more quickly
  • Can be done early 
• BLOOD TEST

  Mother’s blood test is a non-invasive prenatal test

  Possible due to some of the baby’s DNA passing into the mother’s blood
• BLOOD TEST

  Screening test, not a diagnostic - able to identify if there is an increased chance of the baby having a certain disorder, does not confirm whether baby has the disorder
• BLOOD TEST

  When : 

  • Available from approximately week 10
• BLOOD TEST

  Used to screen for : 

  • Down syndrome
  • Edwards syndrome
  • Patau syndrome
  • Turner syndrome

  If they show an increased chance of an abnormality, amniocentesis / CVS would be recommended to confirm the diagnosis
• FOETAL MONITORING

  The regular recording of baby’s heart rate to detect indicators of stress
• FOETAL MONITORING

  Use ultrasound and electrocardiography 

  • Procedure for recording electrical changes in the heart
  • Produces electrocardiogram (ECG), showing series of waves related to electrical impulses that occur during each heartbeat 
  • Results are printed on paper / displayed on monitor
• FOETAL MONITORING

  When : 

  During labour and birth
• FOETAL MONITORING

  Used to : 

  • Identify any risk of injury to the foetus so appropriate action can be taken 
  • Record baby’s heart rate / mother’s contraction during labour and birth 
  • Check whether there is any risk of oxygen deficiency occurring which could result in brain damage / stillbirth
• FETOSCOPY

  Fetoscope is an instrument used to gain information about a foetus in the uterus

  Two types : 

  • Stethoscope
  • listens to the foetus’s heartbeat
  • Fibre-optic scope - looks directly at the foetus through a small, telescope-like instrument with a diameter about the size of a large hypodermic needle

  Introduced into the uterus through abdominal wall
• FETOSCOPY

  Used to (fibre-optic scope) :

  • Detect cleft lip and palate
  • Missing / abnormal ears
  • Deformed / absent limbs
  • Spinal abnormalities, incl. spina bifida
• FETOSCOPY

  Risks : 

  • Difficult procedure only done by specialist doctor 
• FETOSCOPY

  Usually done after ultrasound has indicated possibility of foetal abnormalities (e.g. spina bifida, Duchenne muscular dystrophy)
• FOETAL BLOOD SAMPLING

  Used  to :

  • Diagnose chromosomal abnormalities
  • Diagnose foetal anaemia
  • Check foetal oxygenation
  • Identify infections
  • Give medication
• FOETAL BLOOD SAMPLING

  Blood taken from :

  • Umbilical cord via percutaneous umbilical cord blood sampling (PUBS)

  Needle is inserted through abdominal wall and uterus into umbilical vein

  • Foetal blood vessel, usually the liver or heart, via a fetoscope
• FOETAL BLOOD SAMPLING

  Advantage : 

  • Results are obtained within a few days

  Risks : 

  • 1-2% chance of miscarriage 
  • Infection
  • Blood loss 
  • Premature rupture of amniotic sac
• BIOCHEMICAL ANALYSIS

  Assessment of marker proteins - occurs with all newborns
• BIOCHEMICAL ANALYSIS

  Used to : 

  • Detect phenylketonuria (PKU)

  Test blood for excessive amounts of phenylalanine 

  Analysing urine for phenylpyruvic acid 

  • Measure levels of alpha-fetoprotein (AFP) in amniotic fluid 

  Concentration is high when foetus has malformation of spinal cord 
• DNA PROBES

  Enables the detection of a range of genetic disorders
• DNA PROBES

  Used to diagnose: 

  • Duchenne muscular dystrophy 
  • Thalassaemia
• DNA PROBES

  Based on recombinant DNA technology

  1. Segment of DNA is used that is structurally identical to the gene being tested
  2. Some units in DNA segment are ‘labelled’ with a dye or radioisotope
  3. DNA probe is joined to gene in question
  4. If the gene is normal, DNA probe joins with the DNA segments with which it is structurally identical and shows them up
  5. If it is an abnormal gene, it does not show up and is identifiable as a gap in DNA being tested.