Utility of zona pellucida drilling in cases of severe semen alterations in man

Micromanipulation

Micromanipulation technology entered the forum of human conceptionin vitroin the late 1980s. It was erroneously perceived as a new technology – a purely mechanical approach to bypass failures of conceptionin vitro, the aetiology of which were unknown. In fact, it is the modification of technology developed since the beginning of this century, and its logical utilization for conceptionin vitro, preconception (polar body) biopsy and preimplantation (blastomere and trophectoderm) biopsy in the realm of human infertility and genetic disorders.

Prenatal diagnosis of ring chromosome 14 after intracytoplasmic sperm injection

OBJECTIVE

To collect extensively abnormal cytogenetic results in pregnancies obtained after intracytoplasmic sperm injection (ICSI).

DESIGN

Case report.

SETTING

University Hospital of Nantes, France.

PATIENT(S)

A couple with 5 years of primary infertility and severe male factor undergoing ICSI procedure.

INTERVENTION(S)

Ultrasound-guided transvaginal follicular aspiration, amniocentesis, and medical abortion.

MAIN OUTCOME MEASURE(S)

Serum levels of E2, beta-hCG, and fetal chromosomal karyotype.

RESULT(S)

Ultrasonic observation at 12 weeks revealed an 8-mm thick cystic hygroma in the nuchal area. Because the karyotypic analysis was [46,XX,r(14)/45,XX,-14], medical abortion was performed at 14 weeks, after the patients gave their informed consent.

CONCLUSION(S)

According to the prevalence of this unusual chromosomal abnormality in humans, such abnormal cytogenetic results have to be collected extensively to assess the feasibility of using ICSI procedure.

Abnormal sperm morphology is highly predictive of pregnancy outcome during controlled ovarian hyperstimulation and intrauterine insemination

PURPOSE

The purpose of this study was to assess the predictive value of a modified form of Kruger's strict criteria for sperm morphology for pregnancy outcomes after intrauterine insemination (IUI) and controlled ovarian hyperstimulation (COH) in the presence of normal sperm concentration and motility.

MATERIALS AND METHODS

A retrospective review of 42 couples undergoing COH/IUI was stratified by favorable or unfavorable sperm morphology. End points were pregnancy or failure of treatment as defined by four or more cycles of COH/ IUI without pregnancy.

RESULTS

An unfavorable morphology (< 4%) was highly predictive of failure during COH-IUI (94.45%; 17/18). A normal PIF was a sensitive indicator of those patients who became pregnant (93.8%; 15/16) and had a fair specificity for failure to achieve pregnancy after four cycles of treatment (65.4%; 17/26). Couples with a favorable sperm morphology were 28.3 times as likely to achieve a pregnancy within four cycles of treatment as those with unfavorable sperm morphology [95% confidence limits, 3.2 to 250.5; P < 0.001].

CONCLUSIONS

Abnormal strict morphologic assessment is both sensitive and specific for pregnancy outcomes in couples undergoing COH/IUI. Couples with persistently unfavorable sperm morphology should be counseled appropriately and would be better served by more aggressive treatment with in vitro fertilization and embryo transfer.

Gamete microsurgery for assisted fertilization

Several methods of gamete microsurgery have been proposed to facilitate the union of the spermatozoon and oocyte in infertile couples. Partial zona dissection, subzonal sperm insertion, and intracytoplasmic sperm insertion are the three techniques currently being used for assisted fertilization in human in vitro fertilization laboratories. Fertilization and pregnancy rates after partial zona dissection and subzonal insertion have been variable and rather low. Recent reports of relatively high fertilization and pregnancy rates achieved after intracytoplasmic sperm insertion have rejuvenated interest in gamete microsurgery. Methods for each procedure are described. Studies which have attempted patient selection for gamete microsurgery are discussed.

Embryo viability associated with microassisted fertilization

Embryo morphology and cleavage rates represent useful, but not absolute, measures of embryo viability. Oocyte and embryo chromosomal abnormalities affect embryo viability and are reflected to some degree in the morphology of oocytes and embryos. Microassisted fertilization techniques have been successfully used to treat severe male-factor infertility. Zona drilling using acidified Tyrode's solution is detrimental to oocyte and embryo viability and should not be used. Partial zona dissection (PZD) produces viable embryos that have developmental competence no different from that of routine IVF embryos, but the oocytes should be shrunken in hypertonic sucrose prior to PZD to avoid distortion and mechanical damage. The size of the cut in the zona pellucida is also critical and should be kept to a minimum to avoid loss of blastomeres during transfer. It appears from data on embryo quality, pregnancy rates and implantation rates that SUZI embryos have viability comparable to that of routine IVF embryos. Astonishingly, the passage of an injection needle directly into the ooplasm during ICSI has no effect on fertilization or developmental competence, as demonstrated by the excellent clinical pregnancy rates.

Subzonal insemination and zona breaching techniques for assisting conception in vitro

The following comments can be made with regard to zona breaching procedures (PZD) and SUZI. First and foremost, it is important to establish that fertilization cannot occur with microdrop IVF or conventional IVF before proceeding with microassisted fertilization technology. PZD increases the rate of polyspermy, and this is significantly higher than when utilizing SUZI. SUZI increases the incidence of implantation in cases exhibiting severe teratozoospermia. SUZI increases the fertilization rate per patient and per oocyte in cases where IVF has previously failed on more than one occasion. SUZI increases the incidence of fertilization when very few motile sperm are available, and there is an increase in the incidence of cytoplasmic fragmentation with SUZI, which might be alleviated by improving methods of penetrating the zona pellucida, for example by using the Sonic Sword or utilizing a thinner, sharper injection needle alone or in addition to increasing the perivitelline space by dehydrating the oocyte (Yang et al, 1988). Morphology is an important parameter in predicting the outcome of IVF and therefore in guiding patients on the relevance of microinjection technology.

Medical abortion after in vitro assisted fertilization

Subzonal sperm insertion is an assisted insemination procedure to enhance IVF in patients with severe male factor. We report a lethal fetal abnormality that occurred in a SUZI-obtained pregnancy. It is essential that such cases be extensively collected to assess the feasibility of using this method in patients with severe semen defects.

Subzonal insemination: a prospective randomized study in patients with abnormal sperm morphology

OBJECTIVE

To evaluate in a prospective randomized study the outcome of subzonal insemination (SUZI) in patients with male subfertility.

DESIGN

In a period of 7 months, 48 patients underwent IVF treatment for male subfertility reasons. Normal insemination and SUZI were performed on sibling oocytes. Patients were divided into three groups depending on the sperm morphology (strict criteria): group 1, 10% to 14%; group 2, 5% to 10%; group 3, 0% to 5%.

SETTING

Private fertility center in Leuven, Belgium.

MAIN OUTCOME MEASURES

The fertilization rates, cleavage rates, implantation rates, and pregnancy rates between the normally inseminated and the SUZI-treated group were compared.

RESULTS

The fertilization rate with SUZI was significantly higher (32%) than after normal insemination (7%). The difference was striking in groups 2 and 3 (35% and 33% versus 11% and 4%).

CONCLUSION

This study indicates that SUZI increases the fertility outcome in patients with male subfertility and that there is a marked difference in fertilization rate when morphology, using strict criteria, is < 10%.

Interaction between human sperm cells and hamster oocytes after argon fluoride excimer laser drilling of the zona pellucida

OBJECTIVES

To provide conclusive evidence that sperm cells gain access to the perivitelline space exclusively through a laser-drilled opening. To assess the optimal size of the hole and to evaluate the efficacy of laser drilling in comparison with that of mechanical zona dissection.

DESIGN

An interspecies model of human sperm cell that interacts with a laser-drilled or partially zona-dissected hamster oocytes.

MAIN OUTCOME MEASURES

Penetration rate into the perivitelline space as related to the size of the opening (group A [5 microns], group B [10 microns], and group C [15 microns]) and to the sperm cell concentrations (1 x 10(6), 5 x 10(6), and 10 x 10(6) cells/mL) used for insemination.

RESULTS

For each sperm cell concentration, the penetration rate into the perivitelline space was lowest for group A followed by group C and highest for group B. When penetration was compared for each hole size, it was found that sperm concentration had no effect on the rate of penetration in groups A and C but significantly affected this rate in group B. The highest penetration rate of 73% was observed with a concentration of 10 x 10(6) cell/mL and declined to 58% and 23% at 5 x 10(6) cell/mL and 1 x 10(6) cell/mL, respectively. Oocytes drilled by laser (10-microns hole) demonstrated a significantly higher penetration rate when compared with those treated by partial zona dissection (73% versus 20% and 58% versus 21% for sperm densities of 10 x 10(6) cells/mL and 5 x 10(6) cells/mL, respectively).

CONCLUSION

Human sperm cells gain access into the perivitelline space of hamster oocytes exclusively through a hole drilled by an argon fluoride excimer laser. An opening of 10 microns was found to yield optimal results. Laser drilling of the zona pellucida seems to be superior to that of mechanical slitting in terms of sperm oolema interaction.

Analysis of factors contributing to success in a program of micromanipulation-assisted fertilization

OBJECTIVE

To determine factors important to clinical success in micromanipulation-assisted in vitro fertilization (IVF).

DESIGN

Procedures invoked in two separate series of micromanipulation-assisted IVF cycles, one unsuccessful (series I) and the other successful (series II), were compared in an effort to identify changes that led to clinical success.

SETTING

University-based IVF clinic.

PATIENTS

In both IVF series involving micromanipulation, patients consisted of infertile couples who fit any of five categories of male-factor related infertility. The female patients underwent controlled hyperstimulation for oocyte retrieval and the oocytes were inseminated normally or were subjected either to partial zona dissection or subzonal sperm insertion to assist fertilization. Results in all groups were compared between the two patient series.

RESULTS

In the successful series II, a noticeable improvement in fertilization rate and embryo quality was observed compared with series I. A significant increase in the percentage of patients reaching embryo transfer, the pregnancy rate per transfer, and the pregnancy rate per retrieval were noted in series II; a 25% ongoing pregnancy rate per retrieval was observed overall in this successful group, with "ongoing" defined as manifestation of at least a fetal sac on ultrasound with no detectable problems. Patients with a mixed transfer of embryos derived from manipulated and normally inseminated oocytes had a 75% rate of pregnancy per transfer in series II. Differences between the two series could not be attributed to patient selection or biases in selection of oocytes relegated to micromanipulation. However, oocyte handling, micromanipulation, and culture protocols differed significantly between the two series in that temperature and pH of oocytes was better controlled, and micromanipulation time was minimized in series II.

CONCLUSION

Success in micromanipulation depends on maintenance of the oocyte in a stable and supportive environment throughout the micromanipulation procedure. It is also important to minimize trauma to the eggs by performing micromanipulation rapidly and with minimal distortion of the egg. Patients with a poor fertilization rate in standard IVF may experience a substantial increase in the likelihood of pregnancy when micromanipulation-assisted fertilization is performed on some eggs.