The most recent microassisted fertilization method is called intracytoplasmic sperm injection (ICSI) and involves the injection of a single sperm into the cytoplasm of the oocytes. Reports began appearing in scientific journals in 1992 of consistently successful treatment outcomes following clinical application of ICSI.

ICSI is now widely available in a large number of assisted conception units internationally and has revolutionized the management of male factor infertility. ICSI is associated with fertilization and pregnancy rates similar to those found following conventional IVF in patients who do not have male factor problems.

A group of patients who will benefit from having ICSI at the outset rather than conventional IVF are those who have a marked depression of their semen parameters. This includes patients with moderate to severe oligo-, astheno-, and/or teratozoospermia. Again, pressure may be brought to bear upon the clinician to reason more readily to ICSI, even in men with borderline semen analysis results.

It may be prudent to offer ICSI if the concentration of sperm in the ejaculate is less than 5 million/ml or the progressive motility is less than 10%.

Patients with azoospermia are increasingly being offered ICSI as it is possible to recover sperm, by surgical means, from the genital tract or testes of these men if the azoospermia is obstructive in origin. Even in patients with non-obstructive azoospermia, it may be possible to recover sperm from the ejaculate in up to 35% of cases.

A similar proportion of patients with non-obstructive azoospermia will have sperm recovered from testicular tissue. The quality of sperm retrieved from these patients is poor but the powerful effect of ICSI is such that reasonable fertilization rates and pregnancies result despite this.

Positive pregnancy test results will be obtained in 35% or more of patients who have embryo transfer. The clinical pregnancy and delivery rates will be slightly lower than this but usually 20-25% and above.


Intracytoplasmic morphologically selected sperm injection is a further advancement of technology. Here sperm are analysed using ultra high powered (600x) magnification. Initial studies have shown that IMSI is associated with higher pregnancy rates in couples with repeated implantation failures.However, recent reviews seem to refute any such benefits. Hence more studies to improve the evidence quality are necessary before recommending IMSI in clinical practice.
Embryo Freezing and Frozen Embryo Transfer
Contemporary ovarian stimulation protocols for IVF aim at the production of many oocytes as a way of assuring the generation of enough good quality embryos for transfer. More often than not good quality embryos still remain after transfer of the required number of embryos into the woman and these can be frozen. Survival of frozen embryos after thawing using good techniques is usually above 70% and pregnancy rates following frozen embryo transfers can reach 30% or more. Embryo cryopreservation is therefore a viable component of a assisted conception treatment. There are other indications for embryo cryopreservation. This includes situations where there is a risk of a woman having severe ovarian hyperstimulation syndrome (OHSS); all embryos are frozen and the severe OHSS managed appropriately using drugs, some of which would not have been utilized for fear of teratogenicity if the woman had embryo transfer. When the woman is fully recovered, frozen embryo transfer is carried out (as will be described in the following section). The overwhelming presence of poor prognostic factors in an index IVF treatment cycle may be a reason for freezing all embryos generated. Such factors metrial development and receptivity as can be deduced using ultrasound scanning and Doppler studies. The discovery of uterine pathology during the treatment such as uterine polyps or large, cavity distorting leiomyoma is another indication for embryo cryostorage pending surgical correction of thee structural anomalies.

Embryos can also be frozen in oocytes or embryo donation cycles to allow greater flexibility in scheduling embryo transfers to the recipient.