What is it?In Vitro Fertilisation

The procedure of in-vitro fertilisation (IVF) involves the creation and implantation of a number of 4-8 cell stage embryos in to the uterine wall of women who, for whatever reason, have had difficulties conceiving naturally.

IVF can however, occur in several different variations depending on the exact assisted reproductive technologies/new reproductive technologies (ARTs/NRTs) used to improve the chances of fertilisation, which in turn are dependent on the cause of the individual couple’s infertility.

Variant #1.: Gametes

The sperm used in the creation of the embryo may come from:

  1. The intended father i.e. traditionally the husband (Artificial Insemination by Husband (AIH))
  2. A donor (Artificial Insemination by Donor (AID))

Similarly, the egg used in the creation of the embryo may originate from:

  1. The intended mother
  2. A donor

Variant #2.: Method of fertilisation

The means of fertilisation can also vary depending on the exact method used:

  1. Sub-Zonal Sperm Injection (SUZI):
    Injection of a single harvested sperm just beneath the zona pellucida of a harvested egg. The needle (and sperm) do not therefore directly penetrate the cytoplasm of the ovum itself.

    SUZI is used in cases where a man has decreased sperm numbers, mobility, quality or a anatomical cause of sperm blockage.

  2. Intra Cytoplasmic Sperm Injection (ICSI):
    More recently developed than SUZI involves the injection of a single sperm directly in to the cytoplasm of the ovum itself. ICSI, offered for the same reasons as SUZI has largely replaced the older technology but both are still performed depending on the individual circumstances of those seeking treatment.

    Whilst ICSI is believed to have greater success rates than SUZI concerns have been expressed that ICSI may lead to a greater chance of congenital abnormalities due to disruption to the ovum through the piercing of its membrane. Reports remain mixed with regards to this (due to the technology being too new for any reliable data to yet have emerged) but most clinics conducting the procedure will recommend regular ultrasounds in the first few weeks of pregnancy and the option of amniocentesis at 15 weeks.

  3. Gamete Intrafallopian Transfer (GIFT):
    The eggs are removed from the ovary and mixed with the sperm under in vitro but then returned to the fallopian tube (via laparoscopy) for fertilisation to occur.

    Since the sperm are not directly injected in to the cytoplasm of the egg, GIFT has shown lower success rates than ‘true’ IVF but may be more morally acceptable to certain cultural/religious groups as fertilisation occurs in its ‘natural’ place.

  4. Zygote Intrafallopian Transfer (ZIFT):
    An alternative to GIFT where Fertilisation occurs in a petri dish as with IVF; but immediately transferred to the fallopian tube rather than being allowed to incubate under laboratory conditions.

Intra Cytoplasmic Sperm Injection (ICSI): How it works

Gamete Intrafallopian Transfer (GIFT): Diagram