Microsurgical fertilization and teratozoospermia

Intracytoplasmic sperm injection — ICSI

For more than a decade in vitro fertilization (IVF) has been successful in the treatment of couples with long-standing infertility due to various aetiologies such as tubal disease, male-factor infertility, unexplained infertility and endometriosis. The usual fertilization rate in IVF for nonmale infertility cases is 60–70% of the inseminated cumulus-oocyte complexes and in andrological infertility it is only 20–30%. The lower the number of normally fertilized oocytes, the less chance there is of available embryos, so that patients may have no embryos to transfer. It has been the experience of all centres for reproductive medicine, including our own, that a certain number of couples with male-factor infertility cannot be helped by standard IVF treatment. After insemination with progressively motile spermatozoa the number of two-pronuclear oocytes was either zero or less than 5%. Furthermore, a sizeable number of couples cannot be accepted for IVF if the number of progressively motile spermatozoa in the ejaculate is below a certain threshold number such as 500 000. In the past five years, assisted fertilization procedures have been developed to circumvent the barriers that prevent sperm access to the ooplasma, namely the zona pellucida and the ooplasmic membrane. Pregnancies and births have been reported after partial zona dissection (PZD) and subzonal insemination (SUZI). The success rate of PZD and SUZI has remained moderate: the normal fertilization rate (two-pronuclear oocytes) has never exceeded 20–25% of the micromanipulated oocytes; only two-thirds of the patients have had embryo transfers of, usually, a low number of embryos, resulting in a reduced pregnancy and take-home baby rate.

Intracytoplasmic sperm injection increases embryo fragmentation without affecting clinical outcome

PURPOSE

To examine the effect of intracytoplasmic sperm injection (ICSI) on embryo fragmentation and implantation rates in those embryos chosen for transfer compared to conventional in vitro fertilization (IVF).

METHODS

We compared 253 infertility patients (71 ICSI and 182 IVF) with respect to age, semen analysis, number of embryos transferred, embryo fragmentation, implantation rate, and pregnancy rate. Embryo fragmentation was determined by one observer at the same laboratory over the entire study period.

RESULTS

A statistically significant difference was observed in mean embryo grade between IVF (2.2 +/- 0.84) and ICSI (2.5 +/- 0.77), P = 0.01. Additionally, the IVF patients had significantly more nonfragmented (grade I) embryos compared to the ICSI group, P < 0.01.

CONCLUSIONS

These data suggest that ICSI, irrespective of semen parameters, may increase embryo fragmentation and produce fewer nonfragmented grade I embryos while maintaining implantation and pregnancy rates similar to conventional IVF.

Fertilization after standard in vitro fertilization versus intracytoplasmic sperm injection in subfertile males using sibling oocytes

OBJECTIVE

To compare conventional IVF with ICSI in the subfertile male population using sibling oocytes. Results from males with isolated severe teratozoospermia also are analyzed.

DESIGN

Prospective experimental study.

SETTING

University based IVF clinic.

PATIENT(S)

Group A: 18 patients with one or more abnormalities in count, motility, or morphology. Group B: 20 patients with isolated severe teratozoospermia (< or = 4% Kruger Strict Criteria).

INTERVENTION(S)

Ovulation induction, random allocation of sibling oocytes, and IVF or ICSI.

MAIN OUTCOME MEASURE(S)

Fertilization rates (fertilization per cycle, fertilization per oocytes, and fertilization per couple) and embryo quality.

RESULT(S)

In group A, fertilization occurred in 13 of 18 (72%) of IVF cycles and 17 of 18 (94%) of ICSI cycles. Overall, 69 of 120 (58%) oocytes fertilized after IVF, whereas 80 of 131 (61%) fertilized after ICSI. The mean (+/-SEM) percent of oocytes fertilized per couple was 44.6%+/-9.0% with IVF and 62.7%+/-5.6% with ICSI (not statistically significant). In group B, fertilization occurred in 18 of 20 (90%) cycles after IVF and 20 of 20 (100%) cycles with ICSI. Overall, 54 of 113 (48%) of the oocytes fertilized after IVF, whereas 82 of 124 (66%) fertilized with ICSI. The mean (+/-SEM) percent of oocytes fertilized per couple was 50.9%+/-7.1 % with IVF and 66.6%+/-4.7% with ICSI. No statistically significant difference in embryo quality after IVF versus ICSI was demonstrated.

CONCLUSION(S)

With severe teratozoospermia, ICSI results in higher fertilization rates than conventional IVF, without altering embryo quality. In our subfertile male population, there is a trend toward improved fertilization with ICSI, with less failed fertilization.

Testicular sperm extraction and intracytoplasmic sperm injection: a simplified method for treatment of obstructive azoospermia

OBJECTIVE

To assess the effectiveness of a simple method of testicular sperm extraction for the treatment of obstructive azoospermia.

DESIGN

Retrospective study.

SETTING

Teaching tertiary medical center.

PATIENT(S)

Seventeen men with obstructive azoospermia.

INTERVENTION(S)

The patients underwent 19 cycles of intracytoplasmic sperm injection (ICSI) using testicular sperm. In 5 cycles, testicular sperm extraction was performed after failed microepididymal sperm aspiration. In 14 cycles, testicular sperm extraction was performed in the office under local anesthesia from the outset. The outcome was compared with ICSI cycles using ejaculated sperm (95 cycles) and epididymal sperm (12 cycles fresh and 9 cycles frozen-thawed).

MAIN OUTCOME MEASURE(S)

Clinical pregnancy and implantation rates.

RESULT(S)

There were no differences in the fertilization, cleavage, implantation, or clinical pregnancy rates among ICSI cycles using testicular, epididymal (fresh or frozen-thawed), or ejaculated sperm.

CONCLUSION(S)

When used in conjunction with ICSI, testicular sperm extraction from small excisional biopsy is a simple and cost-effective method for the treatment of obstructive azoospermia.

Fertilization and pregnancy rates after intracytoplasmic sperm injection using ejaculate semen and surgically retrieved sperm

OBJECTIVE

To compare the fertilization rates and pregnancy rates (PRs) in intracytoplasmic sperm injection (ICSI) using sperm from ejaculates of normal and abnormal semen, epididymal sperm, and testicular sperm of obstructive and nonobstructive azoospermic patients.

DESIGN

Retrospective study.

SETTING

The Egyptian IVF-ET Center.

PATIENT(S)

Three hundred fifty patients underwent 366 ICSI cycles.

INTERVENTION(S)

ICSI, epididymal sperm aspiration, and testicular biopsy.

MAIN OUTCOME MEASURE(S)

Fertilization rates and PRs.

RESULT(S)

Patients were divided into five groups according to the quality and source of sperm. Patients in group 1 underwent 102 cycles of ICSI using ejaculated abnormal semen, group 2 underwent 44 cycles using epididymal sperm, group 3 underwent 82 cycles using testicular sperm from obstructive azoospermia, group 4 underwent 80 cycles using testicular sperm from nonobstructive azoospermia, and group 5 underwent 58 cycles using normal semen. There was no significant difference in the fertilization rates and PRs among groups 1, 2, and 3. In group 4, the fertilization rate and PR were significantly lower than in all other groups. In group 5, the fertilization rate was significantly higher than in all other groups.

CONCLUSION(S)

The fertilizing ability of sperm in ICSI is highest with normal semen and lowest with sperm extracted from a testicular biopsy in nonobstructive azoospermia. There was no significant difference in fertilization rates and PRs between ejaculated sperm of different parameters and surgically retrieved sperm in obstructive azoospermia.

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.

Developmental failure in preimplantation human conceptuses

The majority of human conceptuses fertilized normally in vitro fail to establish a pregnancy following their replacement in utero. However, since conceptuses are usually transferred after only one or two cell divisions, their developmental outcome is not known. It has been found that a significant number of human oocytes which can be fertilized carry chromosomal abnormalities, even in the absence of ovarian stimulation. After fertilization, preimplantation-stage conceptuses developing in vitro display a high incidence of cellular abnormalities. Similar disruptions of cellular organization have also been noted in conceptuses fertilized in vivo. Thus, developmental abnormalities and the demise of the conceptus prior to the stage of implantation may stem from the poor quality of the oocyte. The conditions encountered in vitro have also been proposed to cause or contribute to the early demise of human conceptuses.

The effect of sperm parameters on the outcome of intracytoplasmic sperm injection

OBJECTIVE

To investigate the influence of sperm parameters on the fertilization and pregnancy rates in intracytoplasmic sperm injection (ICSI).

DESIGN

A retrospective analysis of 130 cycles of ICSI performed for the treatment of male factor infertility.

SETTING

The Egyptian IVF-ET Center.

PARTICIPANTS

One hundred thirty couples with the diagnosis of male factor infertility or with previous failed fertilization in conventional IVF or subzonal sperm injection.

INTERVENTION

Ovum pick-up and ICSI.

MAIN OUTCOME MEASURE

Fertilization and pregnancy rates in relation to different semen parameters.

RESULTS

A total of 1,433 oocytes were retrieved and 1,071 metaphase II oocytes were injected. Normal fertilization occurred in 620 oocytes (58%). Embryo transfer was done for 128 (98.5%) patients, and a total of 46 (35%) clinical pregnancies were achieved. There was no statistically significant difference in the fertilization or pregnancy rates between patients who had previously failed fertilization in conventional IVF, patients with subfertile semen, patients with semen between 1 and 10 x 10(6)/mL, and patients with semen < 1 x 10(6)/mL. There was also no significant difference in the fertilization and pregnancy rates between patients with < 95% or > 95% teratozoospermia.

CONCLUSION

In ICSI, the fertilization and pregnancy rates are not affected by different semen parameters as long as morphologically well-shaped live sperms could be used for the injection.

Comparison of the acrosome reaction-inducing ability of the outer and inner surfaces of the zona pellucida and oolemma: a study using the golden hamster

The outer surface of hamster zona pellucida has a strong ability to induce the sperm acrosome reaction, whereas neither the inner surface of the zona nor the oolemma has this ability. Therefore, the spermatozoa that fertilise oocytes after subzonal insemination of spermatozoa (SUZI) must have been either acrosome-reacted prior to injection or acrosome-reacted spontaneously while swimming within the perivitelline space. The outer surface of fresh mouse zona is not capable of inducing the acrosome reaction of hamster spermatozoa. When fixed with glutaraldehyde, however, it became capable of inducing the hamster sperm acrosome reaction rather efficiently. The reason for this is not clear.

The effective cumulative pregnancy rate of different modes of treatment of male infertility

The clinical efficacy of conventional and advanced methods of treatment was assessed in 814 couples with infertility due to a male factor. The monthly and effective cumulative rate of ongoing or term pregnancies was calculated during 4712 couple-months. Treatment of varicocele by transcatheter embolization, resulting in 3.9% pregnancies per cycle and an effective cumulative pregnancy rate of 41% after 1 year, is more effective than counselling and timed intercourse (9% pregnancies after 12 months). Intrauterine insemination (IUI) of washed spermatozoa produced 17% pregnancies in the initial 4 months, but the success rate of the subsequent cycles (1.7% per cycle) was not different from that of the controls. In vitro fertilization (IVF) resulted in 16% pregnancies per attempt, but the effective cumulative pregnancy rate was only 31% in 12 months due to the long interval between treatment attempts and the high drop-out rate. With subzonal microinjection of sperm, the fertilization rate was higher (71%) than with regular IVF (29%) but both the pregnancy rate per attempt (9%) and the effective cumulative pregnancy rate (17% after 12 months) were low. The 10th percentile of sperm characteristics (cut-off values) of successful cases showed intrauterine insemination to be advantageous in cases with a lower percentage of spermatozoa with progressive motility (9%) than in the controls (15%). The cut-off value of sperm morphology in IVF (4%) is lower than that of IUI (8%) and of the controls (9%), but higher than that of subzonal insemination (1%). Treatment strategy must be defined selecting or combining conventional and assisted reproductive technology for each individual couple with male factor infertility.

Human sperm chromosome analysis after microinjection into hamster oocytes

PURPOSE

Subzonal sperm insemination (SUZI) into hamster oocytes was performed to establish the karyotypes of the fertilizing spermatozoa.

METHODS

Spermatozoa from two males with normal semen parameters were microinjected. Of 72 (52 + 20) analyzed sperm chromosome metaphases, only 1 (1.4%) was considered abnormal, showing a structural abnormality.

RESULTS

No hyperhaploidy was observed. Rates of sperm chromosomal abnormalities after microinjection were not higher than those reported previously using zona-free egg insemination, suggesting that the SUZI procedure per se does not increase sperm chromosomal abnormalities.

CONCLUSIONS

The use of subzonal insemination into hamster oocytes for the study of human sperm chromosomes in males with low sperm counts is discussed.

A randomized study of intracytoplasmic sperm injection (ICSI) versus subzonal insemination (SUZI) for the management of severe male-factor infertility

OBJECTIVE

Our objective was to compare the fertilization rates achieved by ICSI versus SUZI in couples with severe male infertility.

DESIGN

This was a randomized, prospective study.

SETTING

The study took place at the In-Vitro Fertilization-Embryo Transfer Unit, Department of Obstetrics and Gynecology, The Chaim Sheba Medical Center.

MATERIALS AND METHODS

Oocytes of 12 patients were randomly allocated to either ICSI or SUZI procedures. Each woman thus served as her own control. All 12 patients had undergone at least two previous in vitro fertilization cycles with no fertilization or had a very low sperm count, i.e., a total motile sperm count of less than 0.5 x 10(6).

RESULTS

A total of 117 oocytes was obtained for fertilization. Of these oocytes, 16% (10/63) were successfully fertilized by SUZI, compared to 33% (18/54) treated by ICSI. This difference was statistically significant (P < 0.05). Of the 12 cycles, ICSI provided embryos in 10 cycles (83%), while SUZI was successful in only 6 cycles (50%). Four pregnancies were achieved: 33% per attempt, or 40% per transfer.

Using ejaculated, fresh, and frozen-thawed epididymal and testicular spermatozoa gives rise to comparable results after intracytoplasmic sperm injection

OBJECTIVE

To describe the preparation of fresh or frozen-thawed epididymal and testicular sperm for intracytoplasmic single sperm injection and to compare the fertilization, embryo quality, and pregnancy rates (PRs) obtained after using these spermatozoa to the results when freshly ejaculated sperm was used for microinjection.

DESIGN

Retrospective analysis of 1,034 consecutive microinjection cycles. Ejaculated (965 cycles), fresh epididymal (43 cycles), frozen-thawed epididymal (9 cycles), and testicular sperm (17 cycles) was used for intracytoplasmic sperm injection.

SETTING

Procedures were performed in a tertiary IVF center coupled with an institutional research environment.

MAIN OUTCOME MEASURES

Semen density and motility were judged by the World Health Organization criteria and sperm morphology was evaluated by the Tygerberg's strict criteria. After microinjection, oocyte intactness, fertilization, embryo cleavage, transfer, and PRs were evaluated and compared.

RESULTS

The median values of total sperm count, total motility and normal morphology were 17.85 x 10(6), 37%, 8% for freshly ejaculated sperm; 46.20 x 10(6), 12%, 9% for fresh epididymal sperm; 0.15 x 10(6), 0%, 0% for frozen-thawed epididymal sperm; and 0.54 x 10(6), 0% for testicular sperm (morphology was not determined). The percentage of intact oocytes after microinjection ranged from 84% to 90%. Normal fertilization rates were high when fresh or frozen-thawed epididymal and testicular spermatozoa were used for the injection (56%, 56%, 48%, respectively) but were significantly lower than for ejaculated sperm (70%). There was a higher proportion of transferable embryos obtained after ejaculated sperm injection than after testicular sperm injection. Forty percent, 58%, 33%, and 46% of cycles had positive serum hCG using ejaculated, fresh, or frozen-thawed epididymal and testicular sperm. Initial pregnancy loss occurred in 26.3% of the conception cycles.

CONCLUSION

Intracytoplasmic sperm injection can provide high normal fertilization, cleavage, and PRs when fresh or frozen-thawed epididymal and testicular spermatozoa are used, but normal fertilization rates are significantly lower than after microinjection with ejaculated sperm.

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.

Assisted fertilization with intracytoplasmic sperm injection

OBJECTIVE

To evaluate the significance of intracytoplasmic sperm injection in severe male factor infertility and previous failed fertilization.

DESIGN

Prospective observational study.

SETTING

Private infertility clinic, London.

SUBJECTS

Sixty-nine patients with a long-standing history of infertility of which 48 had previous failed fertilization, 15 had < 1 million progressive motile sperm per ejaculate, and the remaining 6 had obstructive azoospermia.

INTERVENTION

Assisted fertilization with primary intracytoplasmic sperm injection was carried out in 69 IVF.

OUTCOME

Normal (two pronuclei [2PN]) fertilization and pregnancy rates.

RESULTS

A total of 967, oocytes were collected and 785 were subsequently microinjected. Normal fertilization (2PN) occurred in 410 oocytes (52%) and 90.5% of those cleaved. Sixty-four patients underwent ET, with a total of 181 embryos transferred. Twenty-five patients conceived with a pregnancy rate of 39% per transfer. The implantation rate was 16% and the total pregnancy loss rate 24%. Failed fertilization after intracytoplasmic sperm injection occurred in four cases.

CONCLUSIONS

Intracytoplasmic sperm injection is increasingly becoming the treatment of choice in infertile couples where assisted fertilization is indicated. The high fertilization and pregnancy rates observed with this technique, together with a low risk of abnormalities, has revolutionized treatment of male factor infertility.

Subzonal insemination (SUZI) or in vitro fertilization (IVF) in microdroplets for the treatment of male-factor infertility

PURPOSE

The results of subzonal insemination (SUZI) and in vitro fertilization with microdroplet insemination used in couples with male-factor infertility are presented.

RESULTS

The total fertilization rate was 17.4% for SUZI (n = 89) and 49.3% for microdroplet IVF (n = 100). The fertilization rate for standard IVF (n = 510), not including any male-factor infertility and performed during the same period, was 73.2%. The "take-home baby rate" per started cycle and per embryo transfer (ET), respectively, was 10 and 17.6% for SUZI and 20 and 24.7% for microdrop IVF. For standard IVF these figures were 27 and 31.7%.

CONCLUSION

It was concluded that microdroplet IVF can be used with good results in cases of moderate male-factor infertility. The normal (2PN) fertilization rate with the SUZI technique was only 15.1%. However, despite the low fertilization rate, SUZI should be considered when dealing with severe male-factor infertility.

Subzonal insertion of multiple sperm is a treatment for male factor infertility

OBJECTIVE

To determine whether subzonal insemination of multiple sperm is an effective treatment for male factor infertility.

DESIGN

Subzonal insemination by micromanipulation of sperm and oocytes for male factor patients.

PATIENTS

Two hundred eight patients were selected on previous fertilization history and/or semen parameters. They could be assigned to one of three groups: group A had previous IVF failure, group B had a low fertilization rate with previous IVF, and group C had insufficient sperm for IVF.

INTERVENTIONS

Oocytes were inseminated by subzonal insertion of multiple sperm.

MAIN OUTCOME MEASURES

Fertilization and pregnancy rates.

RESULTS

There have been 208 patients treated through 332 treatment cycles. Of 2,789 oocytes inseminated, 784 oocytes were fertilized (28%) and 516 of these (66%) were monospermic. This represents normal fertilization in 207 cycles (62% of total patient cycles). These 207 cycles produced an average of 2.6 +/- 1.8 embryos. The resultant 487 embryos were either transferred or cryopreserved for future transfer. A total of 42 pregnancies (21% per ET) resulted from 200 ET procedures with 397 embryos. Miscarriages or elective terminations have occurred (11/42 pregnancies, 26% to date) and 21 deliveries have resulted in 26 babies. There are nine ongoing pregnancies. Three of the pregnancies have been from cryopreserved embryos. Group B patients had the highest fertilization rate (23%) but the lowest pregnancy rate (7%). No other significant relationships between patient group and outcome were found.

CONCLUSIONS

Subzonal insemination of multiple sperm is an effective treatment for some forms of male factor infertility.

Influence of sperm parameters on embryo quality

OBJECTIVE

To evaluate the influence of sperm defects on embryo quality.

DESIGN

Retrospective study.

SETTING

In vitro fertilization center.

PATIENTS

Embryo transfers (710) from IVF attempts for tubal disease (626) or male infertility (84).

MAIN OUTCOME MEASURES

Embryo morphology as a function of causes of infertility, semen, and follicular growth parameters. Embryos were classified into three groups according to their morphology.

RESULTS

Transfers of embryos with good morphology were associated to a higher pregnancy rate (34%) than those with intermediate (24%) and poor (10%) morphology. Transfers of embryos with a poor morphology were more frequent (26 of 84 versus 114 of 626) and those with a fair aspect were less frequent (24 of 84 versus 229 of 626) in male infertility than in tubal disease. Embryos with a poor morphology were associated with lower percentage of morphologically normal sperms (62% +/- 19% versus 67% +/- 18%; means +/- SD) and a higher percentage of abnormalities of the postacrosomial region (29% +/- 15% versus 18% +/- 7%). Moreover, sperms with counts < 10 x 10(6)/mL were associated with a lower percentage of embryos with good morphology (18% versus 37%) than sperms with counts > or = 10 x 10(6)/mL.

CONCLUSION

Embryo quality is influenced by the semen quality and especially by sperm head abnormalities, suggesting an important role of the male gamete on the early stages of embryogenesis.

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.

Microinjection of human sperm into perivitelline space of hamster eggs: comparison with zona-free hamster egg penetration of human sperm

Micromanipulation of human sperm and oocyte has been utilized to facilitate fertilization of those patients with male factor due to oligoasthenospermia or those patients with repeated fertilization failure in an in vitro fertilization (IVF) program. Before manipulating human gametes, one needs experience with animal models. Our objective was to perform subzonal insertion of human sperm into hamster eggs and to compare the result with that of sperm penetration assay (SPA) using zona-free hamster eggs. Semen samples were obtained from 15 fertile donors with normal semen analysis and the motile sperm were collected by swim-up procedure. Microinjection was performed by injecting a varied number of sperm into the perivitelline space of 222 hamster eggs pretreated with sucrose solution (0.1 M). The rate of damage of eggs during microinjection was 7.2% (16/222). The rates of penetration in the microinjection group were 5.1% (4/79) for 1-5 sperm injected, 10.9% (11/101) for 6-10 sperm injected, and 11.5% (3/26) for 11-15 sperm injected. The average rate of penetration per egg was 8.7% (18/206), and the polyspermic rate was 11.1% (2/18). Simultaneously SPA was performed in each sample of semen as a positive control, and the average rate of penetration of SPA was 51.4% (108/210). The rate of penetration in the microinjection group was significantly smaller (p < .05) than that in the SPA group. Whether the penetration rate and polyspermic rate in a hamster model reflect similar results in human oocyte requires further investigation. However, the hamster egg provides an ideal model to develop a micromanipulation technique for human beings.

Sperm characteristics and outcome of human assisted fertilization by subzonal insemination and intracytoplasmic sperm injection

OBJECTIVE

To investigate the influence of sperm characteristics on the treatment by subzonal insemination (SUZI) and intracytoplasmic sperm injection of couples with severe male infertility.

DESIGN

A retrospective analysis of 300 consecutive cycles of assisted fertilization concerning 202 infertile couples was performed. One hundred fifty-three couples underwent 362 unsuccessful IVF cycles, whereas on 49 couples IVF was not performed because of poor sperm characteristics.

SETTING

Procedures were performed in an institutional research environment.

PATIENTS, PARTICIPANTS

Couples in which the male partner was the presumed cause of repeated failure to achieve conception by IVF or in which seminal parameters were unacceptable for IVF.

INTERVENTIONS

Three hundred transvaginal oocyte retrievals were performed after superovulation by GnRH agonist and gonadotropins.

MAIN OUTCOME MEASURES

After SUZI and intracytoplasmic sperm injection the following parameters were evaluated: fertilization, cleavage, pregnancy, and implantation rates in relation to the sperm parameters and the proportion of acrosome-free spermatozoa after different treatments.

RESULTS

Normal fertilization occurred in 18% of the oocytes treated by SUZI and in 44% after intracytoplasmic sperm injection. Only the treatment by electroporation showed a positive correlation with the fertilization rate. Fourteen pregnancies were obtained after SUZI, 8 pregnancies after intracytoplasmic sperm injection, and 8 pregnancies after a combination of the two procedures. A score calculated from the sperm parameters after selection correlated with the fertilization obtained after SUZI, whereas a score calculated from the parameters before sperm selection correlated with the pregnancy rate. Sperm morphology influenced the implantation rate of the embryos obtained with these two procedures.

CONCLUSIONS

Intracytoplasmic sperm injection and SUZI can successfully treat couples who fail IVF or who cannot benefit from IVF. Different treatments can be applied to semen samples to increase the number of acrosome-reacted spermatozoa. The few significant relations found between sperm characteristics and the outcome of assisted fertilization cannot predict the outcome.

Presence of sperm in the perivitelline space predicts fertilization rate after partial zona dissection

OBJECTIVE

To examine the association of the number of spermatozoa present in the perivitelline space and sperm parameters with fertilization after partial zona dissection in male factor patients.

DESIGN

Partial zona dissection was applied in 62 couples (84 cycles). A total of 524 oocytes underwent partial zona dissection (1/8 of the zona circumference) (partial zona dissection group) and 171 sibling oocytes were not manipulated (control group). A total of 326 manipulated oocytes were examined for the presence of spermatozoa in the perivitelline space.

SETTING

University-based in vitro fertilization (IVF) program.

PATIENTS

Fifty-four (87%) couples had at least one complete failure of fertilization, and 8 (13%) couples had low fertilization rate (< 10%) in previous routine IVF attempts.

MAIN OUTCOME MEASURES

Fertilization rate, cleavage rate, and the number of spermatozoa present in the perivitelline space after partial zona dissection.

RESULTS

Monospermic and polyspermic fertilization rates were 22.3% and 6.7% in the partial zona dissection oocytes and 8.8% and 0.6% in the nonmanipulated oocytes, respectively. The cleavage rate was similar in the partial zona dissection and control group (69.2% and 66.6%, respectively). A total of 81 partial zona dissection embryos and 10 nonmanipulated embryos were transferred to the uterus of 34 women (39 cycles), resulting in four pregnancies. In 46% (18 of 39) of the patients who had both partial zona dissection and control oocytes, only the manipulated oocytes fertilized. In only 48.8% of partial zona dissection oocytes, spermatozoa were detected in the perivitelline space; in this group of oocytes the fertilization rate was 56.6%. Sperm count and morphology were not clearly correlated with the outcome of partial zona dissection.

CONCLUSIONS

The partial zona dissection technique enhances fertilization of subfertile sperm. However, the low efficiency of the procedure, apart from being associated with a high polyspermic rate, is related to the failure of sperm to traverse the slit in the zona pellucida in approximately one half of the manipulated oocytes.

Subzonal sperm microinjection in cases of severe male factor infertility and repeated in vitro fertilization failure

OBJECTIVE

To examine (1) fertilization rates obtained with subzonal sperm microinjection when different numbers of sperm are injected into the perivitelline space; (2) when subzonal sperm microinjection is combined with dilute insemination; and (3) the association of semen quality characteristics with fertilization.

DESIGN

Subzonal sperm microinjection and subzonal sperm microinjection combined with dilute insemination was performed in 109 and 41 cycles on patients in two clinical trials in Melbourne, Australia, and Bologna, Italy, respectively. PATIENT PARTICIPANTS: Couples who have experienced repeated in vitro fertilization failure or in whom the husband has severe male factor infertility.

PRIMARY OUTCOME MEASURES

The number of oocytes fertilized after injection of different numbers of sperm into the perivitelline space, the number of patients transferred, and pregnancy outcome.

RESULTS

The injection of multiple numbers of sperm into the perivitelline space failed to improve monospermic fertilization rates but caused an increase in polyspermic fertilization. In patients with initial semen parameters exhibiting greater than 50% motility or greater than 50% normal morphology fertilization rates were improved when subzonal sperm microinjection-treated eggs were incubated in a dilute insemination medium. Six pregnancies were obtained, two of which have progressed to term.

CONCLUSIONS

When applied to male factor patients, the subzonal sperm microinjection technique results in a 14% to 15% fertilization rate. However, of the 102 embryos transferred only three (2.9%) fetal heart beats were obtained.

Microsurgical fertilization procedures: the absence of stringent criteria for patient selection

Subzonal sperm insertion and partial zona dissection were applied in 250 in vitro fertilization cycles in couples (n = 200) with abnormal semen analyses; 61 clinical pregnancies were established (24% per egg retrieval). Patients were selected without using minimal cutoff criteria. The study included patients with 0% normal sperm forms (strict criteria), no motile sperm (but some live cells), and sperm counts which could be assessed only after centrifugation. Patients were categorized into three subsets. Group A (n = 116 cycles) failed to fertilize in a previous cycle. Group B (n = 40) was excluded from IVF due to the severity of sperm profiles, such as a maximum of 2% normal forms. Group C (n = 94) constitutes those patients for whom a standard cycle could possibly result in failure. Monospermic fertilization rates were 18% (A), 19% (B), and 24% (C). The incidences of embryo replacement were 63% (A), 53% (B), and 69% (C). Rates of clinical pregnancy were 22% (A), 23% (B), and 28% (C). The presence of one, two, or three semen abnormalities did not correlate with the outcome of microsurgical fertilization. Twenty-two percent of patients with combined oligoasthenoteratozoospermia became pregnant. Moreover, ongoing pregnancies were established in instances with 0% normal sperm forms and no progressively motile spermatozoa. It is concluded that stringent cutoff criteria may not be necessary when both partial zona dissection and subzonal sperm insertion are performed efficiently.

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

OBJECTIVE

To evaluate the utility of zona drilling for human severe sperm alterations in in vitro fertilization (IVF).

DESIGN

A prospective randomized study was conducted according to random assignment of collected oocytes to a control or zona drilling procedure.

SETTING

Reproductive Biology Laboratory, University Hospital of Nantes, France.

PATIENTS

Twenty infertile couples with severe semen defects and previous IVF failure.

INTERVENTIONS

Ultrasound-guided transvaginal follicular aspiration.

RESULTS

Fertilization rates were compared to assess the advantages of zona drilling: 93% (80/86) drilled oocytes survived and 18.75% (15) were fertilized, whereas only 3% (3/100) control oocytes were fertilized. The polyspermy rate for fertilized drilled oocytes was high (10/15; 66.6%). The normal fertilization rate after zona drilling remained very low (5/86; 5.8%) and was not statistically different from that of control oocytes (3/100; 3%). One implantation occurred after replacement of five drilled embryos in three patients but resulted in early miscarriage. Replacement of the single control embryo led to a progressive pregnancy and normal male birth.

CONCLUSIONS

This study indicates that zona drilling does not improve IVF results in cases of severe semen alterations.

Partial zona dissection or subzonal sperm insertion: microsurgical fertilization alternatives based on evaluation of sperm and embryo morphology

OBJECTIVE

To establish guidelines for application of partial zona dissection, subzonal sperm insertion, and regular in vitro fertilization (IVF) in severe male factor patients.

DESIGN

Two studies were performed: partial zona dissection and IVF was applied in 57 couples during the first period, and subzonal sperm insertion was also applied in a second group of 47 couples.

SETTING

Procedures were performed in an academic research environment.

PATIENTS, PARTICIPANTS

Couples who failed fertilization previously, others not acceptable for IVF, and a third group in whom IVF was expected to fail.

INTERVENTIONS

Oocytes were micromanipulated with either partial zona dissection or subzonal sperm insertion, or the zona pellucida was left intact. Embryos were replaced in patients prophylactically treated with methylprednisolone and antibiotics.

MAIN OUTCOME MEASURES

Because several microsurgical fertilization techniques are now available, this study was performed to compare sperm parameters, embryo morphology, fertilization, and implantation rates after application of two successful micromanipulation procedures.

RESULTS

Twenty-one pregnancies were established in 104 patients, 5 definitely from subzonal sperm insertion and 4 from partial zona dissection. Patients who failed IVF before had a similar chance of pregnancy after the use of micromanipulation, as first time patients (9/53 versus 12/51). In a subgroup of 15 patients who failed IVF with insufficient numbers of motile sperm, fertilization was significantly higher after subzonal sperm insertion. Partially zona-dissected embryos from couples with severe teratozoospermia (less than or equal to 5% normal forms; strict criteria) had significantly more morphological abnormalities than those from patients with moderate teratozoospermia (6% to 10% normal forms). In severely teratozoospermic patients, significantly fewer partially zona-dissected than subzonally inserted embryos implanted.

CONCLUSIONS

The decision of which micromanipulation method to perform can possibly be based on careful analysis of sperm morphology.