Pre-Implantation Genetic Screening (PGS)
PGS checks the number of chromosomes in each blastocyst and can be useful for:
- women 36 and older with good ovarian reserve,
- people who have had recurrent miscarriage,
- people not pregnant despite the transfer of several embryos – PGS may uncover a higher than expected
chromosome abnormality rate
- patients who are willing to go through more than one egg retrieval cycle to obtain a normal embryo
Time Lapse Morphometry Imaging (TIMI)
Photographs embryos every 10 minutes to capture developmental milestones in the embryo’s life that
are missed when embryos are only inspected once a day.
TiMI can be useful for:
- people who expect to have several good quality embryos
- people who have had low quality embryos previously may experience better embryo development or learn
why embryo development is poor.
High magnification ICSI (IMSI)
When there is significant male infertility, the embryologist injects a sperm into each egg using a technique called ICSI. IMSI is a variation of ICSI using high magnification. ICSI can be useful for
- Men with poor sperm morphology. Poor morphology makes sperm more susceptible to oxidation damage
- Men with a higher level of DNA fragmentation in their sperm. DNA
fragmentation is a sign of oxidation damage
- People with few embryos developing to the blastocyst stage
- People not pregnant despite the transfer of several reasonable quality embryos.
Pre-implantation Genetic Diagnosis ‘PGD’
PGD can be used by people who have a chance of passing serious genetic disorders on to their children, such as:
- Cystic Fibrosis, Huntington’s, Beta-thalessemia, Fragile X and Spinal Muscular Atrophy. These are caused by a change in single gene.
- People who have a high chance of pregnancy loss or a lower chance of pregnancy because of translocations between chromosomes.
Useful to know:
Ethics Committee approval is required to carry out PGD for any other reason (such as ‘saviour siblings’). PGD cannot be used for gender selection in New Zealand.
Genetic Carrier Screening
Genetic carrier screening gives individuals and couple’s information about their risk of having a child with a genetic condition.
It will tell you if you are a carrier for three common inherited conditions:
- Cystic Fibrosis (CF)
- Fragile X Syndrome (FXS)
- Spinal Muscular Atrophy (SMA)
Many people are carriers of Cystic Fibrosis, Fragile X Syndrome and Spinal Muscular Atrophy even though they do not have anybody in their family who has the condition.
- CF or SMA: A couple is only at risk of having a child with CF or SMA if both the father and the mother are carriers of that condition. If you are a carrier of CF or SMA your partner will be offered testing.
Two people who are carriers of the same condition have a 1 in 4 (25%) chance of having a child with the condition for each pregnancy.
- FXS, only women who carry the increased risk gene are at risk of having a child with FXS. This means that your partner will not need to be tested for FXS. Female carriers of the increased risk gene have a 1 in 2 (50%) chance of passing that gene onto each child they have.
Pre Natal Testing
It is possible to detect/screen for fetal abnormalities using non-invasive prenatal testing 'NIPT', Chorionic Villus Sampling 'CVS' or Amniocentesis.
- NIPT (non-invasive prenatal testing) is a blood test performed any time from 10 weeks of pregnancy. The results are available within 5-10 days. NIPT uses cell-free fetal DNA (cfDNA) found in maternal blood to identify the most common chromosome conditions seen in newborns, Trisomy 21 (Down Syndrome), Trisomy 18, Trisomy 13 and Sex chromosome abnormalities including Turner syndrome, Klinefelter syndrome , Triple X and XYY syndrome.
- CVS Chorionic Villus Sampling or Amniocentesis can also be used to confirm a diagnosis in those with a higher risk from the screening result. Screening is free for CVS or Amniocentesis for those at higher risk.
Please ask your Obstetrician, Genetic Counsellor or Lead Maternity Carer for more information