Pregnancy success rates for in vitro fertilization procedures with ICSI have been shown in some studies to be higher than for IVF without ICSI. This is because in many of the cases needing ICSI the female is relatively young and fertile (good egg quantity and quality) as compared to some of the women having IVF for reasons other than male factor infertility. Another way to say this is - average egg quantity and quality is usually better in ICSI cases (male factor cases) because it is less likely that there is a problem with the eggs - as compared to cases with unexplained infertility in which there is more probability of a somewhat reduced egg quantity and quality (on the average, since some women in this group have egg related issues).

ICSI success rates vary according to the specifics of the individual case, the ICSI technique used, the skill of the individual performing the procedure, the overall quality of the laboratory, the quality of the eggs, and the embryo transfer skills of the infertility specialist physician performing the procedure.

Sometimes IVF with ICSI is done for "egg factor" cases - low ovarian reserve situations. This is when there is either a low number of eggs, or lower "quality" eggs (or often both). In such cases, ICSI fertilization and pregnancy success rates are somewhat lower (as a group) since the main determinant of IVF success is the quality of the transferred embryos - and the quality of the eggs is the most crucial factor determining the quality and viability of the resulting embryo.

In some cases, assisted hatching might be done on the embryos prior to transfer, in order to maximize chances for pregnancy.

IVF success depends on a certain number of spermatozoa present in the ejaculated, having good motility and morphology. Riedel et al. the minimum andrological requirements for a conventional IVF; 5 x 106/ml concentration, 30% progressive motility and 30% normal morphology. Men having parameters lower than the appointed values had bad prognostics. Nowadays, however, the best approach to this kind of male infertility is ICSI: only one living spermatozoon is needed for each M II oocyte (oocyte in the metaphase II cell stage – that means – mature).

Before the ICSI era, various attempts were made to modify and refine conventional IVF in order to enhance pregnancy rates in cases of male infertility. The use of high sperm concentration showed good results in oligospermy and oligoasthenospermy. However, sperm morphology plays an important role in the success of this type of IVF.

More recently, when ICSI was already available, comparative studies have been made between high sperm concentration IVF and ICSI, in the cases of severe teratozoospermia. Higher fertilization rates and better embryo quality were obtained through ICSI when compared to high sperm concentration IVF. A clear tendency for better pregnancy and implantation rates was observed in the ICSI group. Nowadays ICSI clearly surpassed of modified conventional IVF techniques, including high sperm concentration insemination, for the treatment of severe male factor infertility.

ICSI is not strictly indicated for morphological alterations of spermatozoa, but also for low sperm motility and concentration. A summary of four years of ICSI practice indicated that similar results are obtained by ICSI using abnormal semen and conventional IVF using normal semen.

ICSI with ejaculated sperm can be successfully used in patients with fertilization failure after conventional IVF and also in patients who cannot be accepted for these procedures due to an ejaculated having less than 500.000 progressive mobile spermatozoa. High fertilization and pregnancy rates can be obtained when a mobile spermatozoon is injected. The injection of an immobile or dead spermatozoon results in low fertilization rates. Absolute asthenospermia is a sporadic condition except for sperm ultra-structural defects. Therefore, if immobile sperm injection in an initial cycle leads to bad results, subsequent ICSI cycles are justified.

In case we find only immobile spermatozoa for microinjection, it is important to select the living ones, and this can be achieved by using the hypo-osmotic swelling test (to look for a swelling in the spermatozoon tail): living spermatozoa having an intact cell membrane show a typical swelling when placed inside a hypo-osmotic saline solution. Only these spermatozoa must be selected for the ICSI procedure. Of course the hypo-osmotic test must be preceded by the eosine Y coloration, to exclude complete necrozoospermia. When only dead spermatic cells are present in the ejaculated, using testicular sperm is indicated. Other seminal parameters, like concentration, morphology (except for globozoospermia) and high anti-sperm antibody rates do not influence ICSI success rates. Success with ICSI has been described for patients with acrosome absence.

Any infertility form associated to excretion duct obstruction can be treated by ICSI, by microsurgically removing sperm from the epidydim or testicle. Obstructive azoopsermia can result from congenital bilateral absence of vas deferens (CBAVD), vasectomy or vasoepidydimostomia reversion failure. Epidydim sperm is obtained mainly by microsurgery of epidydim and sperm aspiration (MESA), under general anesthesia. Other used method is percutaneous epididym sperm aspiration (PESA) preceded by local anesthesia. When immobile sperm is removed from the epidydim, due to an epididymary fibrosis, we can try to remove sperm from the testicles through a biopsy. Two techniques are used to obtain testicular tissue: A biopsy or a thin needle aspiration. Testicular biopsy has also been used in some non obstructive azoopsermia cases. In patients having severe testicular deteriorization and germ cell aplasia (Sertoly cell syndrome only), hypospermatogenesis or incomplete maturation, sometimes sperm can be found after multiple biopsies. Sperm removal may not always be successful in all azoospermic patients. However, there is no precise indicator for testicular sperm removal except testicular histopathology. Optimal spermatozoa removed by testicular biopsy can be obtained by a delicate tissue wash. Very frequently can we find living spermatozoa after enzymatic treatment of testicular samples, for red cell removal.

Cryopreservation of supranumerary spermatozoa removed from the epidydim or testicle has na important function, because frozen or unfrozen sperm microinjection may be used, avoiding surgery in future ICSI cycles. Successful ICSI using frozen epididymal sperm has been described. This also holds true for pregnancy resulting therefrom. Testicular sperm cryopreservation is less frequently used and more difficult, because only a limited number of spermatozoa is present for good results. Cohen et al. have recently described a cryopreservation method with reduced spermatozoon number inside the empty oocyte zona pellucida; although adapting this method for testicular biopsy may take excessive time.

It must be added that ICSI method may not be used in approximately 3% of the cycles. This may result from the fact that the cumulus-corona complex or Metaphase II oocytes are not available, or there couldn’t be found any sperm in testicular biopsies in patients with non obstructive azoospermia.

Due to excellent fertilization rates and good embryo development, ICSI has been indicated for practically all infertility cases, even in the absence of a male infertility factor.

How can ICSI be used to treat men with a zero sperm count (azoospermia)?

For patients with obstructive azoopsermia in whom sperm cannot be found in the epididymis, it is always possible to find sperm in the testis. The easiest way to retrieve this is through TESA or testicular sperm aspiration, in which the testicular tissue is sucked out through a fine needle, under local anaesthesia. The testicular tissue is placed in culture media and sent to the lab, where it is processed. The sperm are liberated from within the seminiferous tubules (where they are produced) and are then dissected free from the surrounding testicular tissue.

Using sperm from the epididymis and testis for ICSI in order to treat patients with obstructive azoospermia is logical, and thus conceptually easy to understand. However, surprisingly, it is possible to find sperm even in patients who have testicular failure (nonobstructive azoospermia) - even in those men with very small testes. The reason for this is that defects in sperm production are "patchy"- they do not affect the entire testis uniformly.

This means that even if sperm production is absent in a certain area, there may be other areas in the testis where sperm production would be normal (this could be because the genetic defect that causes abnormal spermatogenesis may be "leaky"). Since such few sperm are needed for ICSI, we can find enough sperm in over 50 per cent of patients with testicular failure, even if their testes are as small as a peanut!