PGD CGH Clinical

Fertilisation: ICSI (intracytoplasmic sperm injection) - Day 0

The first step in CGH is to amplify the embryo's DNA. This is a sensitive method that will amplify any DNA present into millions of copies.

ICSI is used in CGH to fertilise the eggs and reduce the chance of parental DNA contamination of the PCR analysis. Careful removal of the cells surrounding the egg and injection of a single sperm reduces the possibility of contamination.

Watch the ICSI video

Embryology – the early embryo

The eggs that are fertilised are identified by the presence of pronuclei on Day 1, following ICSI. These embryos are cultured further to Day 3 when the outside zona pellucida is then breached using a low power laser.

Assisted embryo hatching – Day 3

A small hole is created in the zona pellucida on day 3 (6-8 cell stage) using a near infra-red laser. Zona breaching promotes the hatching of a blastocyst on day 5 or day 6.

Embryology – Blastocyst Stage (Day 5/6)

The embryo naturally expands to form a blastocyst - a hollow ball of cells (trophectoderm) with a clump of cells on the inside (inner cell mass). The expanding blastocyst tears the outer zona and hatches.

The assisted hatching on Day 3 allows this natural process to occur a little earlier.

Embryo Biopsy Day 5 or 6

Hatching embryos are held with gentle suction and, using a small glass biopsy pipette, 3-6 trophectoderm cells are removed with the assistance a near infra-red laser. The biopsied cells are then ready for analysis and the embryo is frozen for future use.

view embryo biopsy video - day 5 hatching blastocyst

view embryo biopsy video - day 6 fully hatched blastocyst