In Vitro Maturation (ivm)

Background

In vitro maturation (IVM) of human oocytes is an adjunct treatment to the process of conventional in vitro fertilisation (IVF) within the field of assisted reproductive technologies (ART) used to treat couples that require treatment to resolve their infertility.

What is the process of oocyte in vitro maturation (IVM)?

In vitro maturation (IVM) of oocytes refers to the practice of removing immature cumulus-oocyte complexes from follicles that have yet to complete their growth, and subsequently maturing these oocytes in vitro. Figure 1 illustrates the major differences between IVM and conventional IVF.

Figure 1: Schematic of the major differences between IVM and conventional IVF

Note: Firstly, for IVM, patients receive no or minimal ovarian hormonal stimulation, whereas in IVF patients' ovaries are hyperstimulated with large doses of gonadotrophins. Secondly, in IVF, oocyte maturation occurs in vivo, whereas in IVM, oocyte maturation occurs in vitro for 1–2 days, prior to standard fertilisation procedures.

Which clinical processes are different in IVM?

The majority of the indications for treatment, many aspects of patient treatment and care, and most laboratory practices are common for IVM and IVF. IVM is an additional procedure that is added prior to IVF, which replaces a process that oocytes undertake within ovarian follicles. Within routine IVF procedures this process is manipulated by the administration of exogenous gonadotrophin hormones. The main differences between IVM and IVF treatment cycles are outlined below.

• Patient preparation: Women undergoing IVM either completely forgo ovarian hormonal stimulation prior to egg collection or receive minimal stimulation. This is the single largest benefit of IVM and makes the technology particularly attractive to PCOS and PCO patients (see clause 7). There are number of significant clinical variations on IVM.

– No stimulation: patients receive no hormonal stimulation prior to egg pick-up. This protocol is widely practised in Scandinavia and is particularly used with PCOS and PCO patients, but can also be used for non-PCOS patients.

– FSH priming: patients receive minimal FSH stimulation (3–6 days of low-dose FSH) prior to egg pick-up. This protocol is not widely practised.

– hCG priming: patients receive no FSH and receive one bolus dose of 10,000 IU hCG 36 hours prior to egg pick-up. This protocol is widely practised in Canada and South Korea [1] and is particularly used with PCOS and PCO patients, but can also be used for non-PCOS patients.

– FSH + hCG priming: a combination of (b) and (c) above. This protocol is alternatively called ‘minimal stimulation IVF' although