In an infertility management world which is increasingly becoming devoted to ICSI, IVF or rather Conventional Ivf needs attention. In fact, ICSI is becoming synonymous with IVF. The use of the word ‘conventional’ is now mandatory to separate the two as doing IVF is slowly snowballing into selecting only ICSI.

Intra Cytoplamic Sperm Injection revolutionized the world of infertility but it was prescribed for a certain set of conditions. As we are seeing its rampant usage, IVF is slipping into oblivion. Nevertheless, conventional IVF is still practiced and in this article, we will enlighten you on the steps necessary for successful insemination.

In vitro Fertilization in the conventional sense is actually mimicking outside what happens inside in vivo. As sperm is brought into union with oocyte cumulus complex, one of them will naturally fertilize. It is now understood that the oocyte has to be in metaphase 2 after extrusion of the first polar body before it can fertilize. The human sperm has to undergo changes such as capacitation, the acrosome reaction, and hyper activation before successful fertilization. In conventional IVF, a few sperms commence capacitation and acrosome reaction in the culture media whilst the major part of the acrosome reaction takes place when the sperm comes in contact with the outer Zona pellucida. Fusion of oolemma and the inner acrosomal membrane of the reacted sperm results into complete fertilization and formation of a zygote.

Important steps or points to consider in IVF!

1. 1. The timing of the insemination

Oocyte cumulus complexes collected after aspiration during the ovum pick up procedure require a period of 3 to 6 hours in the incubator at 37 degrees in 5% CO2 for final maturation before insemination can proceed.

This aspect is essential to gain optimal fertilization and implantation rates and also to reduce the incidences of polyspermy.

Insemination of immature oocytes influences zygote formation, cleavage rates, and embryo fragmentation.

2. Semen processing

The most neglected part may be the processing of sperm. In the case of ICSI, we have to choose a single sperm per oocyte and even if we have 100 oocytes, we will just need a hundred sperms. That has reduced the importance of semen processing. In conventional IVF, sperm motility and number carry a lot of weight and it is imperative to efficiently process semen samples.

For example, its important for the semen sample to be liquefied in order to further subject it for processing. In ICSI, even if we process viscous samples, there will be a frustrating experience to immobilize them but still, you can pick and inject them. In conventional IVF, this may impede sperm motility and subsequently hamper fertilization.

Again, its crucial to calculate the amount of sperm to be added rather than a blind addition. This will mean, semen analysis has to be thorough and sound.

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3. Insemination methods

It can be done in different ways. It has been successfully adapted in test tubes, four well dishes, organ culture dishes and even Petri dishes containing micro droplets of culture medium under the layer of oil. Whatever the system adopted, care must be taken to ensure the maintenance of temperature, pH and osmolarity.

1. One or four well dishes

• Visualization of OCC’s is easy and even their mechanical denudation
• But they harbor greater fluctuation in pH and osmolarity
• 50000-100000 sperm per OCC

1. Capillary tubes or straws

    Sperm OCC suspension is introduced in straw or capillary tube using a tuberculin syringe

    Single OCC in 5 to 10ul inseminate with 2000-4000 motile sperm

    Further incubation will commence at 37degrees and 5%CO2

1. Microdroplets under oil

o    Proper exhibition and control of pH and osmolarity.

o    The oil acts as a physical barrier

o    Nevertheless, handling of OCCs can be a messy experience

o    5000 sperm per OCC

In any of the insemination method, media and oil have to be properly equilibrated as per the requirements.

4. Assessment of fertilization

Fertilization is checked 12-16 hours after insemination for the presence of two pronuclei and two polar bodies. In ICSI too fertilization check is important but if not done, embryos can be directly assessed on day 3 or day 5 and transferred.

In conventional IVF, it’s imperative to proceed with mechanical denudation on day 1 as corona cells remain attached to Zona after cumulus dispersal which is usually done by a denuding pipette with a diameter slightly bigger than the oocyte.

After fertilization check, the differences end here and the rest of the cycle is no different than an ICSI cycle. Conventional IVF needs to be done as an effective line of treatment and not as a subsidiary to booming ICSI utilization. The hand of an embryologist may be skilled enough but the realm of natural selection needs to stay!