The effect of intracytoplasmic sperm injection and semen parameters on blastocyst development in vitro

Paternal effect on genomic activation, clinical pregnancy and live birth rate after ICSI with cryopreserved epididymal versus testicular spermatozoa

BACKGROUND

This study takes an in depth look at embryonic development, implantation, pregnancy and live birth rates with frozen epididymal and testicular sperm from obstructed (OA) and non-obstructed (NOA) patients.

METHODS

Paternal effect of sperm source on zygote formation, embryonic cleavage, and genomic activation were examined. Additional outcome parameters monitored were clinical pregnancy rate (CPR), implantation rate (IR) and live birth rate.

RESULTS

In this report, we retrospectively analyzed 156 ICSI cycles using cryopreserved epididymal sperm (ES; n = 77) or testicular sperm (TESE; n = 79). The developmental potential of embryos did not appear to be influenced by the type of surgically retrieved sperm. The average number of blastomeres observed on Day 3 was not different among different groups; 7.5 +/- 1.7 (ES), 7.6 +/- 2.1 (TESE-OA) and 6.5 +/- 2.3 (TESE-NOA). Compaction and blastulation rates, both indicators of paternal genomic activation, were similar in embryos derived from ICSI with ES or TESE from OA as well as NOA men. The only parameter significantly affected in NOA-TESE cases was the fertilization rate. CPR and IR with cryopreserved TESE (TESE-OA 59%, 34%, and TESE-NOA 37%, 20%) were also not statistically different, from that achieved with cryopreserved ES (61% and 39%). Live birth rates also appeared to be independent of sperm type. The 87 clinical pregnancies established using cryopreserved TESE and ES, resulted in the birth of 115 healthy infants. No congenital anomalies were noted.

CONCLUSION

Zygotic activation seems to be independent of sperm origin and type of azoospermia.

A new real-time morphology classification for human spermatozoa: a link for fertilization and improved embryo quality

OBJECTIVE

To understand the correlation between normalcy of the sperm, fertilization, and early embryo development, and to establish a detailed classification scoring scale for the individual spermatozoon with the highest predictive fertilizing potential in real time during intracytoplasmic sperm injection (ICSI).

DESIGN

A retrospective and analysis.

SETTING

Laboratory Drouot.

PATIENT(S)

27 couples with male factor infertility referred for ICSI treatment.

INTERVENTION(S)

Before ICSI, motile spermatozoa were scored after aspiration.

MAIN OUTCOME MEASURE(S)

Oocyte fertilization, embryo development and morphology, outcome of scored motile injected spermatozoa.

RESULT(S)

Our suggested formula is (Normal head score = 2) + (Lack of vacuole score = 3) + (Normal base score = 1) = (Total score = 6) for a morphologic "normal top" spermatozoon, calculated with the major criteria affecting the outcome of ICSI. We take into account the normalcy of head size and shape, the base of the head, and the lack of vacuoles. Our scoring of three classes of injected spermatozoa revealed a statistically significant difference in fertilization rate: 39 out of 46 (84%), 94 out of 128 (73%), and 27 out of 44 (61%), respectively. Our examination of the contribution of maternal age in correlation to sperm score revealed a distinction between oocytes originating from women younger than 30 years and oocytes from women aged 30 years and older.

CONCLUSION(S)

Our suggested classification provides allows the best spermatozoon to be chosen for ICSI, particularly for oocytes from women aged 30 years and older.

Clinical predictors of human blastocyst formation and pregnancy after extended embryo culture and transfer

OBJECTIVE

To determine the clinical factors associated with blastocyst development and pregnancy.

DESIGN

Evaluation of a prospectively collected IVF database.

SETTING

An academic IVF practice.

PATIENT(S)

Couples (n = 529) undergoing their first IVF cycle who qualified for extended embryo culture (more than six zygotes) over the past 5 years.

INTERVENTION(S)

Seven or eight zygotes were cultured for 5 days, assessed for quality, and then transferred with excess zygotes cryopreserved at the pronuclear stage.

MAIN OUTCOME MEASURE(S)

Clinical predictors of blastocyst development and pregnancy.

RESULT(S)

The mean blastocyst development rate was 49.8%, with a median number of total and good-quality blastocysts of 4 and 2, respectively. Clinical factors that were significantly associated with good-quality blastocyst formation were younger female age, increased parity, standard insemination, and lower doses of gonadotropins. Clinical factors that were significantly associated with successful pregnancy were younger female age, higher antral follicle counts, greater numbers of total and good-/excellent-quality blastocysts, and absence of male factor infertility.

CONCLUSION(S)

Several clinical factors are associated with the development of good-quality blastocysts after extended embryo culture and successful pregnancy outcome. These patient and cycle characteristics may be very useful in selecting the best candidates for extended embryo culture and single blastocyst transfers, thus optimizing outcomes while reducing the risks associated with multiple pregnancies.

Embryo development after intracytoplasmic sperm injection can be predicted by assessment of sperm nuclear chromatin

Purpose

To assess the influence of structural differences in sperm nuclei on embryo development in intracytoplasmic sperm injection (ICSI).

Methods

Semen obtained from forty-four infertile patients who underwent ICSI was examined. In assessing blastocyst development, only those patients who had successfully obtained over five fertilized eggs were included to exclude any oocyte factors (n = 22). Spermatozoa were assessed using excitation fluorescence flow cytometry with acridine orange and the sperm chromatin dispersion (SCD) test.

Results

There was a significant positive correlation between the COMP values obtained from flow cytometry and blastocyst formation. (r = 0.477, p = 0.025). There was a significant negative correlation between the SCD values representing DNA fragmentation and blastocyst formation. (r = 0.796, p < 0.001). COMP values and SCD values were independent parameters to assess sperm nuclear quality regarding embryo development in vitro (r = 0.224, p = 0.080).

Conclusion

Results suggest that injection of spermatozoa with fewer disulfide bonds and less nuclear DNA fragmentation could achieve better blastocyst formation in human ICSI. Assessment of sperm chromatin should help to predict embryo development after ICSI.

Does severe teratozoospermia affect blastocyst formation, live birth rate, and other clinical outcome parameters in ICSI cycles?

OBJECTIVE

To determine if strict morphology correlates with outcome parameters in couples undergoing intracytoplasmic sperm injection (ICSI).

DESIGN

Retrospective review.

SETTING

Academic nonprofit IVF center.

PATIENT(S)

Couples undergoing IVF/ICSI.

INTERVENTION(S)

In vitro fertilization and ICSI.

MAIN OUTCOME MEASURE(S)

Samples were evaluated for total sperm count, motlity, progression, and morphology using Kruger's strict criteria. The ICSI cycle outcome parameters included fertilization, clinical pregnancy, implantation, live birth, and blastulation rates and blastocyst quality.

RESULT(S)

Fertilization rates were high (74%-77%), and clinical pregnancy rates ranged from 60% (subgroup with 0% normal sperm) to 56% (subgroup with >/=7% normal forms). The highest pregnancy and live birth rates were observed in eggs fertilized with sperm from specimens with the most severe teratozoospermia. The blastulation rate was similar among subgroups. The percentage of high-quality blastocysts was significantly greater in the severely teratozoospermic patients compared with patients with >/=5% normal sperm (37% vs. 28%). This is likely because in the lower morphology subgroups, female factors are less prevalent and the primary infertility problem is male factor.

CONCLUSION(S)

These data suggest that we reconsider the diagnostic value of strict morphology in assisted reproductive technology cycles involving ICSI. Sperm morphology assessed by Kruger's strict criteria had little prognostic value in ICSI cycle outcomes. Sperm morphology did not appear to influence blastocyst development or blastocyst morphology. Microscopic selection of sperm with "normal" morphology during the ICSI procedure allowed excellent outcomes even in samples with severe teratozoospermia.

Effect of glutathione on the development of rat embryos following microinsemination

Purpose

The present study was carried out to evaluate the role of glutathione on rat embryo developmental potential after ICSI. We observed the effects of glutathione on the development of non-treated rat embryos, ICSI embryos and embryos with sham injection treatment. The development of glutathione-microinjected embryos was also observed.

Methods

Oocytes and fertilized embryos were obtained from superovulated Wistar-Imamichi rats and cultured in mR1ECM medium. Oocytes and embryos were then allowed to develop to assess the effect of glutathione on the development rate in intact embryos, micro-injected embryos and ICSI embryos.

Results

(1) In the intact embryo, the proportion of blastocyst stage development increased when 0.01 mM GSH was added to the medium compared to the control. (2) Microinjection of glutathione (GSSG, GSH) into the embryo increased development at each stage, and the addition of 0.2 nM GSSG or GSH significantly increased blastocyst development, in comparison to that of the control (P < 0.05). (3) Compared to the control, all the GSSG and GSH concentrations improved damaged blastocyst development, where 0.01 mM GSH improved significantly (P < 0.05). (4) The addition of glutathione in the medium increased the rate of blastocyst development after ICSI. A significantly higher number of TE and total cells were obtained in the micro-injected embryo with both of the 0.02 mM GSSG and GSH treatments (P < 0.05).

Conclusions

The addition of glutathione into the culture media can improve early embryo development and is capable of repairing the damage of ICSI rat embryos.

Murine pre-embryo oxygen consumption and developmental competence

PURPOSE

In search for a new marker of preimplantation embryo viability the present study investigated oxygen consumption of individual cleavage stage murine embryos, and evaluated the predictive value regarding subsequent development to expanded blastocysts.

METHODS

In all, 248 embryos were investigated from 2 cell stage until blastocyst stage with individual measurement of oxygen consumption and recording of developmental stage. Cleavage stage embryos and morula were divided in groups according to their oxygen consumption, and odds ratios (OR) for subsequent development to expanded blastocyst were calculated.

RESULTS

Cleavage stage (2-8 cell) individual oxygen consumption was 0.16-0.20 nl O(2) h(-1), with a significant increase to 0.21-0.23 nl O(2) h(-1) at the morula stage followed by a more than twofold increase for the expanded blastocyst 0.47 nl O(2) h(-1). A significantly higher chance of reaching the expanded blastocyst stage was found in 4-cell embryos with high oxygen consumption, than embryos with low consumption (OR 2.25, 95% CI 1.04-4.90). Among 2-cell embryos the chance of low and high consumers was not significantly different. The method used in the present study somewhat compromised embryo development (51% blastocyst rate) compared to controls (80% blastocystrate) which could make our results less robust.

CONCLUSION

Preliminary data from the present study suggest that oxygen consumption in cleavage stage embryos may be an indicator, but a not a strong predictor, of subsequent development to expanded blastocysts.

Comparing intracytoplasmic sperm injection and in vitro fertilization in patients with single oocyte retrieval

OBJECTIVE

To compare the efficacy of intracytoplasmic sperm injection (ICSI) and conventional IVF in patients with favorable and poor sperm parameters in which only a single oocyte was available for insemination.

DESIGN

Retrospective analysis.

SETTING

University-affiliated IVF center.

PATIENT(S)

A total of 311 patients (425 cycles) who underwent either stimulated or spontaneous IVF cycles that resulted in single oocyte retrieval.

INTERVENTION(S)

The ICSI was indicated when fertilization failure was anticipated because of sperm quality or other confounding female factors.

MAIN OUTCOME MEASURE(S)

Fertilization rates and pregnancy rates (PRs) were analyzed according to the woman's age (< or =39 or >39 years), sperm quality, and mode of insemination.

RESULT(S)

In patients <39 years old with favorable semen quality, ICSI and standard insemination produced similar fertilization rates (67.1% vs. 75.0%) and PRs (0.0 vs. 8.2%). Conversely, in cases with apparent lower semen quality, ICSI gave a significantly higher fertilization rate (85.4% vs. 44.2%) but no significant difference in PRs (14.6% vs. 4.7%). In patients >39 years old and with favorable semen quality, ICSI and standard insemination produced similar fertilization rates (82.4% vs. 68.4%) and PRs (0.0 vs. 1.1%). The ICSI for lower semen quality, however, produced both higher fertilization rates (84.0% vs. 52%) and higher PRs (8.0% vs. 0).

CONCLUSION(S)

Our results suggest that in poorly responding patients, semen quality should remain the most important determinant when considering whether to perform ICSI. We have found that the values of 20 x 10(6)/mL and 35% motility are good predictors of success in such patients.

Single blastocyst transfer after ICSI from ejaculate spermatozoa, percutaneous epididymal sperm aspiration (PESA) or testicular sperm extraction (TESE)

PURPOSE

To investigate the outcome of IVF following intracytoplasmic sperm injection (ICSI) from ejaculate, percutaneous epididymal sperm aspiration (PESA) and testicular sperm extraction (TESE), with subsequent blastocyst culture and single blastocyst transfer.

METHODS

Single blastocyst transfer was performed after ejaculate ICSI (oligozoospermia) in 587 patients, TESE/PESA (azoospermia) in 31 patients, and standard IVF in 680 women.

RESULTS

There were only minor differences in IVF characteristics between the standard IVF and the PESA-TESE couples. Couples where ejaculate ICSI were performed seemed to represent a slightly poorer prognostic group. A viable fetus after the 12th gestational week, i.e. ongoing pregnancy, was present in 41.4% after ICSI/ET, 51.6% after PESA-TESE/ET and in 40.4% after standard IVF/ET (no significant differences).

CONCLUSION

Single blastocyst transfer after ejaculate ICSI or after PESA/TESE appears to give similar results as conventional IVF blastocyst culture.

Effect of apoptosis and reactive oxygen species production in human granulosa cells on oocyte fertilization and blastocyst development

PURPOSE

The aim was to establish the impact of human granulosa cell apoptosis and reactive oxygen species (ROS) production on fertilization competence of the oocyte, embryo developmental stage and implantation rate.

METHODS

Thirty women undergoing IVF-ET for tubal factor infertility were included; GnRH antagonists and gonadotrophins were used for ovarian stimulation. Granulosa cells were isolated from each aspirated follicle using gradient centrifugation. Apoptosis was studied by flow cytometry using annexin V and propidium iodide. ROS production was studied with hydroethidine staining and analyzed by flow cytometry.

RESULTS

There were no differences in characteristics of granulosa cells between the follicles with fertilized and non-fertilized oocytes. The analyzed characteristics of granulosa cells in corresponding follicles had no effect on embryo developmental stage on day 5. The percentage of ROS producing granulosa cells was lower in the follicles giving rise to blastocysts that resulted in implantation compared to those that did not (39.9% versus 69.9%, P = 0.031).

CONCLUSIONS

Apoptosis and ROS production in granulosa cells have no significant impact on fertilization and do not correlate with the development of blastocysts. An increased percentage of ROS producing granulosa cells results in fewer oocytes retrieved and diminishes implantation rate.

The role of paternal chromosomes and sperm morphology on the outcome of intracytoplasmic sperm injection

The study investigated the possible relationship between the X/Y chromosomes bearing spermatozoa and the outcome of intracytoplasmic sperm injection (ICSI) therapy and morphological appearance/shape (Tygerberg criteria) of the sperm cell injected into the oocyte during ICSI therapy and fertilisation. Thirty-nine patients were recruited for the study from an assisted reproductive programme. Semen samples were prepared by using gradient centrifugation techniques. Prior to injection sperm images were captured using high-quality video graphic equipment. Sperm selection was based on the concept of 'best-looking' spermatozoa i.e. spermatozoa lacking gross and obvious malformations such as broken necks, cytoplasmic droplets, amorphous or elongated heads. Photomicrographs of each sperm cell were produced from video footage. The photographical material was used to determine the basic shape and the actual length-to-width ratio of the injected sperm heads. Embryo biopsies and fluorescent in situ hybridisation (FISH) was performed on 12 randomly selected couples from a set of 39. Embryos were evaluated on day 3 for development and embryo transfer. Embryo biopsies and FISH analyses were performed on those embryos that showed no developmental potential following injection. It was found that 70% of the embryos that showed no developmental potential were Y chromosome-bearing embryos. The sperm selection process for ICSI based on the approach of choosing the 'best-looking' spermatozoon in the ejaculate seems to provide cells that can be classified as normal based on the length-to-width ratio set by the World Health Organization for normal cells.

Incomplete denudation of oocytes prior to ICSI enhances embryo quality and blastocyst development

BACKGROUND

Granulosa cells are essential mediators of oocyte maturation and fertilization. Because of the denudation of oocytes in preparation for ICSI, any potential positive effect of surplus cumulus cells (CCs) on further development would be unable to exert further effect. In order to evaluate the actual influence of adhering cumulus cells on further preimplantation development, this prospective study was carried out.

METHODS

Sibling cumulus-oocyte complexes for 57 ICSI patients were split into a study group (incomplete denudation, n = 314) and a control group (complete denudation, n = 336). According to the cumulus cell pattern after partial denudation, mature gametes from the study group were further subdivided into type A oocytes, which showed several prominent CC clusters (n = 202), and type B (n = 75), which showed a more homogeneous pattern with CC covering the whole surface of the gamete.

RESULTS

In immature oocytes, presence of adhered CCs led to a significant increase in resumption of meiosis (P < 0.01). Fertilization rate (P < 0.05) and ability to cleave (P < 0.01) was impaired in the study group, because of difficulties in ICSI of type B oocytes. By contrast, embryo morphology on days 2 (P < 0.01) and 3 (P < 0.05), as well as blastocyst formation, was better (P < 0.05) in the study group (55 blastocysts out of 88 zygotes) as compared to that in the control group (49/105).

CONCLUSION

These data indicate that co-culture of oocytes with attached CCs may enhance preimplantation development.

Does the presence of nuclear vacuoles in human sperm selected for ICSI affect pregnancy outcome?

BACKGROUND

To verify whether or not microinjection of sperm with a normal nuclear shape but large vacuoles affects IVF-ICSI pregnancy outcome.

METHODS

A comparative study testing IVF outcome parameters of IVF-ICSI, based on morphological selection of spermatozoa with normal nuclei against those based on microinjection of sperm with a normal nuclear shape but large vacuoles. An experimental group, including 28 IVF-ICSI cycles, where only embryos obtained from microinjection of spermatozoa with a normal nuclear shape but large vacuoles were transferred, was matched with a control group, including 28 IVF-ICSI cycles, where only embryos obtained from microinjection of spermatozoa with a strictly defined morphologically normal nuclear shape and content were transferred. The main outcome was IVF-ICSI pregnancy rate.

RESULTS

The experimental group exhibited a significantly lower pregnancy rate per cycle and significantly higher abortion rate per pregnancy compared to the control group (18 versus 50%, and 80 versus 7%, respectively, P=0.01).

CONCLUSION

Microinjection of vacuolated sperm appears to reduce the pregnancy rate and appears to be associated with early abortion.

Increased ammonium in culture medium reduces the development of human embryos to the blastocyst stage

The objective of this prospective study was to evaluate the effect of ammonium accumulated in sequential media and determined by enzymatic spectrophotometric method on the blastocyst development in 281 human embryos from 100 stimulated and natural in vitro fertilization (IVF) cycles. Ammonium concentration was increased in 62% of cycles and was correlated negatively with the blastocyst development after classical IVF, but not after intracytoplasmic sperm injection (ICSI).

Blastocyst formation in in vitro fertilization versus intracytoplasmic sperm injection cycles: influence of the fertilization procedure

OBJECTIVE

To compare the quality of early cleaving embryos and blastocysts obtained by IVF or intracytoplasmic sperm injection (ICSI).

DESIGN

Retrospective study.

SETTING

Tertiary infertility center.

PATIENT(S)

Sibling oocytes of 104 patients in 104 IVF vs. ICSI cycles.

INTERVENTION(S)

Cumulus oocyte complexes (n = 1,358) were randomly subjected to ICSI or IVF.

MAIN OUTCOME MEASURE(S)

Embryo development and blastocyst formation rate. The blastocyst quality and cycle efficiency were also evaluated.

RESULT(S)

Early embryo cleavage was higher after ICSI (37.1%) compared to IVF (14.1%). The percentage of > or =4-cell embryos on day 2 and > or =8-cell embryos on day 3 was similar for both procedures. The overall blastocyst formation was not different between ICSI (50.2%) and IVF (54.8%), neither was the percentage of good-quality blastocysts (31.3% for ICSI and 36.0% for IVF). The total cycle efficiency (percentage of embryos transferred and frozen per two pronuclei [2PN]) was comparable for the two techniques (51.7% for ICSI and 57.4% for IVF).

CONCLUSION(S)

No differences were found on sibling oocytes in the embryo development and blastocyst formation, irrespective of the fertilization procedure. Earlier suggestions that the ICSI technique may result in impaired blastocyst development were not confirmed in this study.

Clinical experiences of ICSI-ET thawing cycles with embryos cryopreserved at different developmental stages

PURPOSE

The aim of our study was to analyze factors including survival, implantation and pregnancy rate, patients' age and BMI, abortions and extra uterine pregnancies that might influence the outcome of ICSI-ET thawing cycles.

METHODS

A total of 147 cycles with embryos cryopreserved at different developmental stages were retrospectively evaluated.

RESULTS

No difference was found in the survival, implantation and pregnancy rates of embryos cryopreserved on Day 2-3 and 5. However, in the pregnant group significantly higher implantation rate was observed with Day 5 blastocysts then with Day 2 or 3 early embryos. We found no difference in the number of abortions and extra uterine pregnancies between fresh and frozen ICSI-ET cycles. Higher BMI was found in the pregnant than in the nonpregnant group. However, the age of patient had no effect on the results.

CONCLUSIONS

Developmental stage of embryo and patients' BMI influences the success of ICSI-ET thawing cycles.

World Health Organization grade 'a' motility and zona-binding test accurately predict IVF outcome for mild male factor and unexplained infertilities

BACKGROUND

The aim of this study was to determine the pronostic value of a sperm-zona pellucida (ZP) binding assay, combined with World Health Organization (WHO) grade 'a' sperm motility on the day of the IVF attempt, to predict sperm fertilizing ability in unexplained and moderate male factor infertilities.

METHODS

In total, 84 couples (64 unexplained infertility; 20 male factor) underwent both a sperm-ZP binding assay and an IVF attempt, irrespective of the test's result. The test was negative when grade 'a' motility was #5% and/or the ZP binding index was <0.7. Fertilization and pregnancy rates were related to the test's results.

RESULTS

Thirty-one patients had a negative test (group N) and 53 a positive test (group P). A difference was observed concerning the fertilization rate [median (range): 0 (0-75%) versus 50 (0-100%); P = 0.0001] and the number of cycles with fertilization rate <20% (65 versus 23%; P = 0.0002) between groups N and P respectively. In the group of unexplained and male factor infertilities, the test showed a sensitivity of 83 and 60%, specificity of 50 and 90%, positive predictive value of 76 and 86%, and negative predictive value of 61 and 69% respectively.

CONCLUSION

Sperm-ZP binding test, combined with WHO grade 'a' motility assessment, is relevant to prevent IVF fertilization failures in unexplained infertility and, most particularly, in moderate male factor infertility.

Growth rate of human preimplantation embryos is sex dependent after ICSI but not after IVF

BACKGROUND

There is concern that IVF and/or ICSI might have an adverse effect on embryonic development via epigenetic alterations. Such alterations might also be involved in the sex-related growth differences in preimplantation embryos found in some animal species. In the present study we analysed cell numbers of human male and female surplus embryos that developed to the blastocyst stage after either IVF or ICSI in order to investigate possible sex-dependent differential growth rates.

METHODS

Blastocysts resulting from surplus embryos obtained after either IVF or ICSI during a 5 year study period were analysed using fluorescence in situ hybridization (FISH).

RESULTS

The number of cells and sex could be determined in 330 blastocysts collected from 92 IVF cycles and in 322 blastocysts collected from 121 ICSI cycles. Whereas female and male embryos originating from IVF showed comparable mean log cell numbers per embryo +/- SEM (3.76+/-0.05 in 147 female and 3.72+/-0.04 in 183 male embryos), significant differences were observed in embryos originating from ICSI (3.57+/-0.05 in 162 female and 3.90+/-0.03 in 160 male embryos). The sex-related growth difference was significantly greater in ICSI than in IVF embryos. In a subset of 84 embryos, inner cell mass (ICM) and trophectoderm (TE) were analysed separately. A significantly higher mean log cell number of TE cells in ICSI male embryos was found as compared to their female counterparts (3.44+/-0.12 in 16 female and 3.90+/-0.11 in 29 male embryos), whereas this difference was not found in IVF embryos.

CONCLUSION

A clear sex-related growth difference was found in human blastocysts originating from ICSI, but not in blastocysts originating from IVF. It is as yet unknown which mechanism is responsible for our findings. We hypothesize that the ICSI procedure might interfere with the process of imprinted X-inactivation.

Role of reactive oxygen species in gynecologic diseases

Free radicals derived from molecular oxygen and nitrogen are highly reactive metabolites called reactive oxygen species (ROS). Cells continuously produce free radicals and ROS as part of the metabolic process. They are involved in the various functions of the reproductive system. Antioxidants are enzymes or compounds that scavenge and reduce the presence of free radicals. Normally, a balance exists between concentrations of reactive oxygen species and antioxidant scavenging systems. The disruption of the delicate balance between pro- and antioxidants results in oxidative stress. Oxidative stress has been implicated in embryo fragmentation, DNA damage, apoptosis and poor pregnancy outcome. It has also been implicated in a large number of gynecologic diseases, such as endometriosis, pre-eclampsia and maternal diabetes. The use of antioxidants may be beneficial in combating the harmful effects of oxidative stress in many of these diseases. The present review outlines the importance of these species in the pathology of various gynecologic diseases. (Reprod Med Biol 2004; 3: 177 - 199).

Use of surgical sperm retrieval in azoospermic men: A meta-analysis

OBJECTIVE

To compare the outcome of intracytoplasmic sperm injection (ICSI) cycles [1] using epididymal and testicular sperm in patients with obstructive azoospermia (OA); [2] using surgically retrieved sperm in patients with OA and nonobstructive azoospermia (NOA); and [3] using fresh and frozen-thawed sperm.

DESIGN

Meta-analysis of published data.

SETTING

Assisted conception unit.

PATIENT(S)

Ten reports (734 cycles: 677 transfers) were identified as suitable to assess source of sperm; 9 reports (1,103 cycles: 998 transfers) to assess etiology; and 17 reports (1,476 cycles: 1,377 transfers) to assess the effect of cryopreservation.

INTERVENTION(S)

Surgical sperm retrieval/ICSI.

MAIN OUTCOME MEASURE(S)

Fertilization rate (FR), implantation rate (IR), clinical pregnancy rate (CPR), and ongoing pregnancy rate (OPR) per embryo transfer.

RESULT(S)

Meta-analysis demonstrated no significant difference in any outcome measure between the use of epididymal or testicular sperm in men with OA. Meta-analysis showed a significantly improved FR (relative risk [RR] 1.18; 95% confidence interval [CI]: 1.13-1.23) and CPR (RR 1.36; 95% CI: 1.10-1.69) in men with OA as compared to NOA with a nonsignificant increase in OPR. There was no difference in either IR or miscarriage rate between the two groups. Comparing fresh with frozen-thawed epididymal sperm there was no difference in FR or IR, a significantly higher CPR (RR 1.20; 95% CI: 1.0-1.42), and no difference in OPR. No difference in fertilization or pregnancy outcome was noted when the testicular cycles were analyzed separately, but IR was significantly impaired using frozen-thawed sperm (RR 1.75; 95% CI: 1.10-2.80).

CONCLUSION(S)

Meta-analysis of published data confirms that etiology of azoospermia and cryopreservation of surgically retrieved sperm impacts on ICSI outcome, and allows us to make several recommendations for clinical practice. Origin of sperm, in men with similar etiology, does not affect outcome.

Sperm chromatin structure assay (SCSA) parameters are related to fertilization, blastocyst development, and ongoing pregnancy in in vitro fertilization and intracytoplasmic sperm injection cycles

OBJECTIVE

To determine the relationship between sperm chromatin structure assay (SCSA) parameters (DNA fragmentation index [DFI] and high DNA stainability [HDS]), and conventional IVF and IVF/intracytoplasmic sperm injection (ICSI) outcomes.

DESIGN

Retrospective review and prospective study.

SETTING

Private IVF clinic.

PATIENT(S)

Two hundred forty-nine couples undergoing first IVF and/or ICSI cycle.

INTERVENTION(S)

IVF, ICSI, blastocyst culture.

MAIN OUTCOME MEASURE(S)

DFI, HDS, conventional semen parameters, IVF, ICSI.

RESULT(S)

IVF and ICSI fertilization rates were not statistically different between high- and low-DFI groups. More men with > or =15% HDS had lower (<25% and <50%) IVF fertilization rates. High DNA stainability was not related to ICSI fertilization rates. High DNA stainability did not affect blastocyst rates or pregnancy outcomes. Men with > or =30% DFI were at risk for low blastocyst rates (<30%) and no ongoing pregnancies. Men with > or =30% DFI had more male factors. World Health Organization thresholds were not predictive of ongoing pregnancy.

CONCLUSION(S)

The relationship between HDS and poor IVF fertilization rates provides preliminary evidence that ICSI may be indicated in men with > or =15% HDS. Men with high levels of DNA fragmentation (> or =30% DFI) were at greater risk for low blastocyst rates and failure to initiate an ongoing pregnancy. The SCSA provides valuable prognostic information to physicians counseling couples before IVF and/or ICSI cycles.

Assessment of embryo viability: the ability to select a single embryo for transfer--a review

By being able to select the most viable embryo(s) within a given cohort it will be possible to reduce the number of embryos transferred in a given IVF procedure. Several morphological scoring systems have been proposed for the successive stages of human embryo development. Other indicators of embryo viability include rate of cleavage. Finally, non-invasive methods of assessing nutrient uptake and utilization have been developed that can be used to measure the health of individual embryos. A sequential scoring system has therefore been proposed that uses the above parameters in order to create a history for each embryo during the preimplantation period. Such systems will help lead to single embryo transfers for the majority of IVF patients.

Predictive value of the number of oocytes retrieved at ultrasound-directed follicular aspiration with regard to fertilization rates and pregnancy outcome in intracytoplasmic sperm injection treatment cycles

OBJECTIVE

To determine the number of oocytes sufficient for satisfactory fertilization and pregnancy rates in intracytoplasmic sperm injection cycles.

DESIGN

A retrospective analysis.

SETTING

A private assisted conception unit.

PATIENT(S)

Women in whom at least one oocyte was retrieved in consecutive ultrasound-directed follicular aspirations between June 1999 and June 2001.

INTERVENTION(S)

Standard protocol for pituitary down-regulation and ovarian stimulation.

MAIN OUTCOME MEASURE(S)

Number of oocytes retrieved, embryos transferred, fertilization, and pregnancy rates.

RESULT(S)

The numbers of oocytes obtained per cycle were classified into groups A, B, C, and D, consisting of 110, 124, 96, and 122 cycles, with 1-5, 6-10, 11-15, >15 oocytes retrieved from each patient in each group, respectively. The chance of not obtaining a viable oocyte for injection was highest in group A (5.5%). Most fertilization failures occurred in group A (11.8%). Total cleavage failure occurred in the greatest percentage of cycles in group A (3.6%) with a significantly lower mean number of embryos (1.9 +/- 1.7) being transferred. The clinical pregnancy rate was also lowest in group A (7.1%) compared with groups B (25.8%), C (20.8%), and D (23.8%).

CONCLUSION(S)

Retrieval of between 6 and 10 oocytes per patient and transfer of a maximum of three cleavage-stage embryos results in high pregnancy rates.

Overnight incubation improves selection of frozen–thawed blastocysts for transfer: preliminary study using supernumerary embryos

A study was undertaken to determine whether the interval between thawing and transfer influences both biological and clinical outcomes of cryopreserved blastocysts, using supernumerary embryos cultured in sequential media. One hundred and seventy-two patients who underwent blastocyst thawing without any exclusion criteria were included in this single center prospective study of blastocyst thawing cycles. Outcome of 338 blastocysts originating from culture of supernumerary embryos in sequential media was analyzed after 4 or 20 h of culture between thawing and transfer. Survival rate, re-expansion and hatching rates for surviving blastocysts, implantation rates (IRs), pregnancy and miscarriage rates were studied. Blastocyst survival was not influenced by the incubation time after thawing; however both re-expansion and hatching rates were increased after 20-h incubation. Moreover, the IR per thawed or transferred blastocyst was increased three-fold after 20-h incubation compared to 4-h incubation. Increasing the interval between thawing and transfer appears to be beneficial in order to better select for transfer frozen-thawed blastocysts.

Seminal reactive oxygen species as predictors of fertilization, embryo quality and pregnancy rates after conventional in vitro fertilization and intracytoplasmic sperm injection

High seminal reactive oxygen species (ROS) are related to poor semen quality and impaired fertilization. We aimed at finding whether there is an association between ROS and fertilization, embryo quality and pregnancy rates after conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). In prepared semen of 147 male partners of infertile couples, ROS were assessed with luminol chemiluminescence. Spermiogram was assessed in native semen. ROS were negatively correlated with standard sperm characteristics and testicular volume, and positively with abnormal sperm head morphology. Fertilization rate and embryo morphology on day 2 and on day 4 were assessed in 41 IVF and 106 ICSI cycles. The influence of maternal (female age and number of oocytes) and paternal (sperm motility, morphology and ROS) factors on fertilization and embryo quality were assessed by means of regression analyses. After IVF, fertilization and pregnancy rates were negatively associated with ROS level (p = 0.031 and 0.041, respectively). In case of higher ROS, significantly fewer ICSI-derived embryos (p = 0.036) reached the morula-blastocyst stage on day 4. High seminal ROS levels are associated with impaired sperm fertilizing ability and lower pregnancy rates after IVF. In ICSI, a negative association of ROS with embryo development to the blastocyst stage has been observed.

Day 3 versus day 5 embryo transfer: a prospective randomized study

Transfer of embryos at the blastocyst stage has been associated with exceptionally high implantation rates. There are, however, only a few prospective randomized studies comparing day 3 versus day 5 embryo transfer. Furthermore, the number of embryos replaced in the day 3 group transfer is often higher than the number of blastocysts replaced, thereby affecting implantation rates. A total of 118 patients undergoing standard IVF/intracytoplasmic sperm injection who had developed at least three 8-cell embryos showing <20% extracellular fragmentation on day 3 were randomized for day 3 or day 5 transfer. A maximum of two embryos were replaced. In this prospective, randomized study the implantation and pregnancy potential of embryos transferred on day 3 or day 5 were compared. Equal numbers of embryos were replaced in the two groups. There was no statistically significant difference between day 3 and day 5 transfer regarding positive human chorionic gonadotrophin rates (70 versus 67%), clinical pregnancy rates (61 versus 51%), implantation rates (44 versus 37%), twinning rates (42 versus 41%) and rates of early pregnancy loss (15 versus 29%). Transfer of embryos on day 3 or 5 showed similar implantation rates when equal numbers of embryos were transferred. Embryo transfer at the blastocyst stage seems to have no advantage over day 3 transfer in patients with more than two 8-cell embryos showing less than 20% fragmentation on day 3.

Effect of ICSI on subsequent blastocyst development and pregnancy rates

PURPOSE

To investigate whether ICSI (intracytoplasmic sperm injection) results in decreased blastocyst formation and pregnancy compared to IVF (in vitro fertilization).

METHODS

We performed a retrospective analysis of blastocyst transfer (BT) offered routinely to patients under age 40 with > or = three 8-cell embryos on day 3 and compared IVF to ICSI cycles. Sequential media were used with P1 until day 3, then Blastocyst Medium until day 5/6.

RESULTS

There were 131 IVF and 75 ICSI cycles. There was no difference in age, number of oocytes, zygotes, 8-cell embryos, blastocysts on days 5 and 6, or embryos transferred. Progression to blastocyst was similar (78% for IVF and 73% for ICSI) as was the viable pregnancy rate (51.4% for IVF and 55% for ICSI). No cycles failed to form blastocysts.

CONCLUSIONS

The progression to blastocyst and the likelihood of conceiving a viable pregnancy were unaltered by ICSI. Thus it seems appropriate for programs to offer BT to patients undergoing ICSI using the same inclusion criteria applied to their IVF patients.

Blastocyst culture: facts and fiction

The use of sequential media has made extended culture and transfer of blastocysts feasible for human IVF. Embryo transfer on day 5 has been claimed to result in higher implantation rates than transfer on day 3, on the basis of retrospective comparative studies. This is not supported convincingly, however, in randomized controlled trials published to date. Blastocyst culture imposes additional requirements in terms of personnel, equipment, education and cost and is associated with a greater incidence of monozygotic twinning and cycle cancellation rate than in the case of day 3 culture. In order for day 5 transfer to replace day 3 transfer, a convincing comparison between the two methods should therefore demonstrate the superiority of blastocyst transfer. There is still a need for properly designed randomized controlled trials to compare day 3 with day 5 transfer which will also address the effectiveness of a single blastocyst replacement in reducing the incidence of multiple pregnancies as well as the value of blastocyst cryopreservation.

Sperm single-stranded DNA, detected by acridine orange staining, reduces fertilization and quality of ICSI-derived embryos

PURPOSE

The aim of this study was to evaluate the effect of sperm single-stranded DNA, detected by acridine orange (AO), and classical sperm parameters on embryonic quality after ICSI.

METHODS

Before ICSI, the spermatozoa of 183 infertile patients with oligo-, astheno-, teratozoospermia (n = 147), or more than one previous unsuccessful conventional IVF attempt (n = 36) were stained by AO to assess the presence of single-stranded DNA. Two days after ICSI, the embryos of 135 patients were scored for morphology, fragmentation included. Embryos of 48 couples were cultured for 4 days to develop to the morula or blastocyst stage. At most 2 embryos were transferred on Day 2 or 4.

RESULTS

When the level of spermatozoa with single-stranded DNA was increased, there was a significantly lower fertilization rate after ICSI. Besides, increased sperm single-stranded DNA resulted in a higher proportion of heavily fragmented embryos on Day 2 (P < 0.05). In patients with an increased level of spermatozoa with single-stranded DNA, a significantly higher number of embryos were arrested in spite of prolonged culturing (P < 0.05). Classical sperm parameters did not affect the quality and developmental potential of ICSI-derived embryos. No correlation was found between the level of spermatozoa with single-stranded DNA, pregnancy rate, and live-birth rate achieved by ICSI, except in patients with 0% of spermatozoa with single-stranded DNA, in whom the pregnancy rate was significantly higher.

CONCLUSIONS

Sperm single-stranded DNA provides additional data on sperm functional capacity in terms of fertilization and embryonic quality after ICSI.

Blastocyst culture in human IVF: the final destination or a stop along the way?

In the field of human IVF, culturing embryos to the blastocyst stage has gained popularity within the past few years. The impetus to transfer blastocysts has been spurred by several factors: 1) the desire to improve implantation rates in infertility patients, 2) a desire to reduce the multiple pregnancy rate by transferring fewer embryos, 3) the desire to perform pre-implantation genetic diagnosis, and 4) the advent of sequential media. Although culturing human embryos to the Hastocyst stage has improved implantation rates and reduced the incidence of multiple pregnancies in some patient populations, it has not worked for all populations of infertility patients. Factors that may affect the ability of a human embryo to reach the blastocyst stage include the patient's age, cohort of ova retrieved, the use of intracytoplasmic sperm injection of blastomere biopsy, culture conditions, or intrinsic factors within the embryo itself. Culture of human embryos to the blastocyst stage can be an effective method for improving implantation rates and reducing the high order multiple pregnancy rates seen in human IVF clinics when more than three embryos are transferred.