Results of conventional IVF are negatively impacted when the semen characteristics (count, morphology and motility) of the male partner are below acceptable values. The percentages of oocytes which fertilize normally are significantly lower, result in the formation of many fewer embryos and therefore the choice of embryos is limited and the number of embryos available for transfer reduced.

At the end of the 1980s several ART procedures were developed and applied in couples where conventional IVF could not be used. These included partial zona dissection, or PZD in which a small opening was made in the zona pellucida allowing the sperm direct access to the oolemma (cell membrane). The next technique to be introduced was subzonal insertion, or SUZI in which a few motile sperm were microinjected through the perivitelline space. However, the overall experience with PZD and SUZI was that the percentage of eggs that fertilized normally was too low for routine clinical use.

In natural fertilization (as seen in the image above) sperm compete and when the first sperm enters the egg cell, the egg cell blocks the entry of any other sperm.

In 1992, the first pregnancies and deliveries after replacement of embryos generated by Intracytoplasmic Sperm Injection (ICSI) were published. It was noted at the time that fertilization was significantly better using ICSI than SUZI and more embryos suitable for transfer were obtained. Current thinking according to the ASRM states that if viable sperm are available pregnancy rates should be comparable to those achieved using conventional insemination.

The ICSI procedure, in which a single sperm is injected directly into the egg, is done under a microscope using micromanipulation devices (micromanipulators, microinjectors and micropipettes). A holding pipette stabilizes the mature oocyte and from the opposite side a thin, hollow needle is pierced into the inner part of the oocyte, the oolemma. It is loaded with a single sperm that will be released into the oocyte. The pictured oocyte below has an extruded polar body at about 12 o'clock indicating its maturity. After the procedure, the oocyte will be placed into cell culture and checked on the following day for signs of fertilization.

ICSI sperm injection into oocyte Courtesy: RWJMS IVF Laboratory
Available at: http://en.wikipedia.org/wiki/Image:Icsi.JPG

Most couples with severe male factor infertility can be treated with ICSI. The procedure can also be applied with sperm extracted from the epididymis and testis in cases of obstruction of the seminal excretory ducts. Additionally, ICSI is indicated in cases of repeated fertilization failure after conventional IVF, in the presence of a high concentration of anti-sperm antibodies, in patients with spinal cord injury, ejaculatory disturbances, and men with retrograde ejaculation. ICSI can be used when semen was banked prior to vasectomy or in cancer patients in remission when sperm were cryopreserved prior to chemotherapy and radiation.

Techniques such as ICSI and surgical sperm retrieval have given many couples with male factor infertility the chance to reproduce a genetically related child. Research suggests there is not an increased risk of genetic disorders in the offspring conceived using this technique however, men with severely compromised semen characteristics have a higher frequency of chromosomal abnormalities. Since these men can still reproduce there is a chance that their offspring may also be infertile and require medical intervention. Your health care provider may suggest genetic counseling to discuss these issues before proceeding.

References:
Practice Committee of the American Society of Reproductive Medicine. Does intracytoplasmic sperm injection (ICSI) carry inherent genetic risks? Fertil Steril 2004; 82: Supplement 1: S151-S152

Braude P, Rowell P (2003) ABC of subfertility: Assisted conception. II-In vitro fertilisation and Intracytoplasmic sperm injection. BMJ 327:852-855

Colombero LT, Hariprashad JJ, Tsai MC, Rosenwaks Z, Palermo GD. Incidence of sperm aneuploidy in relation to semen characteristics and assisted reproductive outcome. Fertil Steril 1999; 72:90-6

Devroey P, Van Steirteghem A (2004) A review of ten years experience of ICSI. Hum Reprod Update. 10:19-28

Johnson MD. Genetic risks of intracytoplasmic sperm injection in the treatment of male infertility: recommendations for genetic counseling and screening. Fertil Steril 1998;70:397-411

Meschede D, Lemcke B, Exeler JR, De Geyter C, Behre HM, Nieschlag E, et al. Chromosome abnormalities in 447 couples undergoing intracytoplasmic sperm injection-prevalence, types, sex distribution and reproductive relevance. Hum Reprod 1998; 13:576-82

Martin RH, Rademaker A. The relationship between sperm chromosomal abnormalities and sperm morphology in humans. Mutat Res 1988; 207:159-64

Palermo G, Joris H, Devroey P, Van Steirteghem AC. Pregnancies after intracytoplasmic sperm injection of single spermatozoon into an oocyte. Lancet 1992; 340:17-8

Schlegel PN, Palermo GD, Alikani M, Adler A, Reing AM, Cohen J, et al. Micropuncture retrieval of epididymal sperm with in vitro fertilization: importance of in vitro micromanipulation techniques. Urology 1995;46: 238-41

Schlegel PN, Palermo GD, Goldstein M, Menendez S, Zaninovic N, Veeck LL, et al. Testicular sperm extraction with intracytoplasmic sperm injection for nonobstructive azoospermia. Urology 1997;49: 435-40

Wennerholm UB, Bergh C, Hamberger L, Westlander G, Wikland M, Wood M. Obstetric outcome of pregnancies following ICSI, classified according to sperm origin and quality. Hum Reprod 2000; 15:1189-94

Wikipedia. Available at: http://en.wikipedia.org/wiki/Intracytoplasmic_sperm_injection