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Biomedical subjects

Basak Balaban

Publications and source records attributed to Basak Balaban.

At least 19 recordsLinked to original sources
PubMed2006

Utilization of high-security straws for embryo freezing in an in vitro fertilization program: a prospective, randomized study.

OBJECTIVE: To compare the outcome of frozen-thawed ET cycles where embryos had been stored in conventional versus ionomeric resin-based, high-security straws (HSSs). DESIGN: Prospective, randomized study. SETTING: Private assisted-reproduction unit. PATIENT(S): Three hundred and six freeze cycles, and 197 thaw cycles. INTERVENTION(S): Day 3 embryos (n = 1,268) were frozen, and 517 were thawed using HSSs. Alternately, day 3 embryos (n = 1,228) were frozen, and 505 were thawed using conventional straws. MAIN OUTCOME MEASURE(S): Cryosurvival, cleavage and morulae formation rates, and clinical pregnancy, implantation, and multiple pregnancy rates. RESULT(S): Although cycle characteristics did not show any differences, the cryosurvival rate was higher in the HSS group (94.7%) than in the conventional straw group (86%), as was the morulae formation rate (58.7% versus 42.7%). Despite a similar number of embryos being transferred, the clinical pregnancy rate (PR) was higher in the HSS group, but the difference lacked statistical significance (42.5% versus 31.2). Implantation rates (19.4% versus 11.4%) and multiple PRs (41.8% versus 16.6%) were significantly higher in the HSS group than in the conventional straw group. CONCLUSION(S): High-security straws are high effective in human embryo cryopreservation, because they provide higher cryosurvival and implantation rates, as well as a lower risk of cross-contamination compared to conventional straws.

Adult↗
PubMed2006

Impact of fresh-cycle variables on the implantation potential of cryopreserved-thawed human embryos.

OBJECTIVE: To compare the clinical outcomes of cryopreservation according to the indications for freezing and the outcomes of the fresh cycle from which the embryos were derived. DESIGN: Retrospective study. SETTING: Private assisted-reproduction unit. PATIENT(S): Three thousand, three hundred and sixty-eight embryos in 702 frozen-thawed embryo transfer (ET) cycles. INTERVENTION(S): Clinical outcomes of frozen-thawed ET cycles in which embryos were derived from fresh conception cycles (n = 436), from fresh nonconception cycles (n = 180), or where the fresh cycle was cancelled due to impending ovarian hyperstimulation syndrome (OHSS) (n = 86). MAIN OUTCOME MEASURE(S): Cryosurvival, clinical pregnancy, and implantation rates. RESULT(S): Despite similar cryosurvival rates and the transfer of a similar number of embryos, significantly higher clinical pregnancy and implantation rates were obtained in the fresh-conception and OHSS groups. The implantation potential of frozen-thawed embryos that were not selected in a prior fresh cycle was comparable to that of embryos selected for fresh transfer. CONCLUSION(S): The success of frozen-thawed ET depends on the outcome of fresh ET and the indications for cryopreservation. Success is similar to that of fresh ET cycles in patients who had all their embryos frozen due to impending OHSS.

Adult↗
PubMed2006

Laser-assisted hatching increases pregnancy and implantation rates in cryopreserved embryos that were allowed to cleave in vitro after thawing: a prospective randomized study.

BACKGROUND: Cryopreservation of embryos may lead to zona hardening that may compromise in vivo hatching and implantation following thawing and transfer. Assisted hatching (AH) has been advocated as a means of assisting the natural hatching process and enhancing implantation. METHODS: The aim of this study was to assess in a prospective randomized manner the effect of laser-assisted hatching (LAH) on implantation as well as clinical and multiple pregnancy rates (the primary outcome) after the transfer of frozen-thawed embryos. All embryos were thawed the day before transfer, and LAH was performed the next day on embryos that cleaved. Control group consisted of embryos that were transferred without AH. RESULTS: The performance of LAH significantly increased implantation (9.9 versus 20.1%, P < 0.01), clinical pregnancy (27.3 versus 40.9, P < 0.05) and multiple pregnancy rates (16 versus 40.3%, P < 0.07). In the LAH group, significantly more excess embryos that were left in culture hatched in vitro. CONCLUSIONS: LAH improves the outcome of frozen-thawed embryo transfer when performed before transfer on embryos that were allowed to cleave.

Cryopreservation↗
PubMed2006

Randomized comparison of two different blastocyst grading systems.

A more detailed blastocyst grading system provides a better selection of blastocysts with the highest implantation potential. Grading systems will help to decrease the number of blastocysts to be transferred without compromising high implantation and pregnancy rates.

Adult↗
PubMed2006

Effect of oocyte morphology on embryo development and implantation.

Assessment of oocyte morphology is a difficult task, since underlying mechanisms that change the appearance of the oocyte are multifactorial and complex. Significant morphological variations are known to exist among oocytes that may affect the developmental competence and implantation potential of the derived embryo. Morphological variations of the oocyte may result from intrinsic factors such as age and genetic defects or extrinsic factors such as stimulation protocols, culture conditions, and nutrition. The effect of these morphological variations of the oocyte on embryo development and implantation, however, is not conclusively defined because of methodological flaws inherent to most of the studies in the literature. This review will mainly discuss morphological markers of oocyte quality/viability in relation to the oocyte morphology and attempt to clarify whether morphological evaluation of the oocyte can be utilized for predicting the implantation potential of the derived embryo.

Cytoplasm↗
PubMed2005

Impact of the presence of one or more multinucleated blastomeres on the developmental potential of the embryo to the blastocyst stage.

A retrospective study of 5,982 embryos in 619 blastocyst-stage embryo transfer cycles revealed that detection of multinucleated blastomeres either on day 2 or 3 signifies a poor prognosis for blastocyst formation and that no good-quality blastocyst can be expected from an embryo with more than one multinucleated blastomere. Patients should be counseled regarding a poor prognosis when multiple embryos with multinucleated blastomeres are present.

Adult↗
PubMed2005

Comparison of two sequential media for culturing cleavage-stage embryos and blastocysts: embryo characteristics and clinical outcome.

This study was undertaken to compare the outcome of day 3, day 5, and frozen-thawed embryo transfer cycles where embryo culture was undertaken using the G1.2-G2.2 versus GIII series sequential media. A total of 400 day 3, 73 day 5 and 126 frozen-thawed embryo transfer cycles were analysed. Treatment cycles were quasi-randomized on the day of oocyte retrieval to embryo culture in G1.2-G2.2 versus GIII series sequential media. Randomization was undertaken according to alternating weekdays. Significantly more embryos were of grade 1 or 2 quality on day 3 in the GIII group (P < 0.05). Likewise, more embryos in the GIII group had eight blastomeres on day 3 (P < 0.05) and were able to hatch spontaneously (P < 0.05). For day 3 embryo transfer cycles, implantation and clinical pregnancy rates were 14.4 and 25.7% versus 37.8 and 50.3% in G1.2-G2.2 and GIII groups respectively (P < 0.05). For day 5 embryo transfer cycles, implantation rates were significantly higher (29 versus 45%; P < 0.05) in the GIII group. There was a trend towards higher pregnancy rates; however, this did not reach statistical significance due to fewer cycles analysed in this group. In-vitro culture in GIII series sequential media yields better quality embryos that implant more efficiently, compared with culture in G1.2-G2.2 media.

Blastocyst↗
PubMed2005

Is there still a place for co-cultures in the era of sequential media?

Co-cultures have been advocated in assisted reproduction owing to the inadequacy of simple media to support embryo development beyond the cleavage stage. Different human and non-human cells and cell lines have been used for co-cultures. High rates of blastocyst formation have been reported with the use of co-cultures, and they have been proposed as a salvage treatment option in couples with repeated implantation failures. Since the advent of complex sequential media, which yield very high blastocyst formation and blastocyst implantation rates, the need for co-cultures has been questioned. Upon review of the literature, it is evident that well-designed randomized studies that compare co-cultures with simple or sequential media do not exist. Progression to the blastocyst stage for cleavage stage embryos appears to be similar, if not better, for embryos that are cultured in modern sequential media, rendering the use of co-cultures obsolete. Furthermore, there is no consensus regarding the necessity of sequential media, as similar results have been obtained with a single medium formulation that supports all stages of the preimplantation period. Whether co-cultures are beneficial in patients with repeated implantation failures, however, should be investigated in randomized trials. Co-cultures still serve as powerful tools for understanding embryo metabolism. Furthermore, co-cultures may be instrumental in studying expression of implantation-related genes and embryo-endometrium interaction.

Blastocyst↗
PubMed2005

Recurrent implantation failure in assisted reproduction: how to counsel and manage. A. General considerations and treatment options that may benefit the couple.

Recurrent implantation failure is a distressing phenomenon, both for the infertile couple and for the physician responsible for their treatment. Aetiology is often not clear and treatment options are vague. Particularly when transferred embryos are of good quality, recurrent implantation failure may be attributed to less than optimal embryo transfer technique, pathological lesions of the uterine cavity, the presence of hydrosalpinges, fibroids and endometriosis. Poor embryo quality, especially when repetitive, is a major impediment to successful implantation and cannot be corrected at the present time. Molecular abnormalities at the endometrial level and abnormal embryo-endometrium dialogue may be responsible for some cases of recurrent implantation failure. Furthermore, there may be over- or under-expressed genes that may be related to successful implantation. At the present time, the physician confronted with a couple presenting with recurrent implantation failure should discuss openly the potential causes of this phenomenon, with special emphasis on correctable causes, and offer remedies that are evidence based.

Counseling↗
PubMed2005

Recurrent implantation failure in assisted reproduction: how to counsel and manage. B. Treatment options that have not been proven to benefit the couple.

The success of assisted reproduction, although gradually increasing over the years, is still less than satisfactory. Many couples have benefited from this treatment; however, many have also been left frustrated following multiple failed attempts. Couples who fail to conceive after multiple IVF/intracytoplasmic sperm injection (ICSI) treatments often seek treatment options that are new and that have not been offered before. Some of these include immunological testing and treatment, allogenic lymphocyte therapy, intratubal transfer of zygotes and embryos, blastocyst transfer, sequential embryo transfer, assisted hatching, co-cultures, and preimplantation genetic screening for aneuploidy. Although the evidence behind some of these is more robust, most suffer from lack of well designed randomized trials comparing them with other treatment options. Randomized studies are extremely difficult to conduct, as couples will resist being randomized into a treatment group where previously failed procedures will be repeated. In the mean time, assisted reproduction programmes should resist offering treatment options that are not evidence based, or at least they should share with the couple the information that is available and should stress that none of these is a panacea for their problem.

Aneuploidy↗
PubMed2005

Is there a possible correlation between chromosomal variants and spermatogenesis?

AIM: Heterochromatin polymorphism is considered a variant of a normal karyotype but is more frequent in infertile men. The aim of this study was to evaluate the correlation between heterochromatic variants and male infertility and to discuss the possible mechanisms of how heterochromatic polymorphism might affect spermatogenesis. METHODS: Cytogenetic analysis was undertaken in 210 infertile males who had been taken into assisted reproductive techniques and in 183 men with proven fertility. Additionally, C-banding was performed in men with heterochromatin polymorphism. Sperm fluorescence in situ hybridization (FISH) was applied in 54 men with normal karyotype presenting either normal or abnormal sperm parameters as well as in 8 men with heterochromatin polymorphism. The outcomes of assisted reproductive techniques were compared between infertile men with normal karyotype and men with heterochromatin polymorphism. RESULTS: The incidence of heterochromatin polymorphism was higher in infertile men. The most frequent chromosome involved in heterochromatin polymorphism was chromosome 9. Sperm FISH analysis revealed an increased rate of aneuploidy in men with heterochromatin polymorphism. Laboratory and clinical outcomes in assisted reproductive techniques were compromised in men with heterochromatin polymorphism. CONCLUSIONS: An increased rate of heterochromatin polymorphism in infertile males seems to be more than an incidental finding, and must not be considered as a normal variant. Polymorphic heterochromatin may have deleterious effects on the genetic constitution of spermatozoa. More attention must be directed to infertile men with heterochromatin polymorphism.

Adult↗
PubMed2004

Impact of oocyte pre-incubation time on fertilization, embryo quality and pregnancy rate after intracytoplasmic sperm injection.

Although, it is well known that pre-incubation of oocytes prior to conventional IVF improves fertilization and pregnancy rates, there are conflicting results regarding the effect of pre-incubation time in ICSI. This study evaluated the role of pre-incubation of oocytes on outcome in intracytoplasmic sperm injection (ICSI) cycles. A total of 1260 patients undergoing their first ICSI cycles were evaluated retrospectively. In patients undergoing ICSI during the year 2000 (Group I, n = 670), oocytes were injected immediately after retrieval, whereas in patients undergoing ICSI during 2001 (Group II, n = 590), oocytes were incubated for 2-4 h prior to injection. The mean age of patients was 33.9 +/- 5.04 years and 34.1 +/- 5.06 years in groups I and II, respectively. The number of oocytes with a first polar body (MII) and fertilization and cleavage rates were higher, and embryo quality was significantly better in group II. In contrast, the total numbers of oocytes without a first polar body (MI), those where germinal vesicle breakdown had not occurred (GV), and empty zona oocytes were higher in group I. No difference was found in the number of embryos transferred or implantation or clinical pregnancy rates. This study demonstrated that pre-incubation of oocytes prior to ICSI is associated with improved maturation of oocytes, fertilization and embryo quality.

Adult↗
PubMed2004

Pronuclear morphology predicts embryo development and chromosome constitution.

The relationship between pronuclear morphology on the one hand, and embryo development and chromosomal status on the other, was evaluated in 68 couples scheduled to undergo preimplantation genetic diagnosis because of advanced maternal age or recurrent implantation failure. Zygotes were grouped according to their pronuclear (PN) morphology. During the period from fertilization to embryo transfer, cleavage rate, embryo quality, blastocyst formation and results of the chromosomal analysis of 240 embryos were recorded. Both embryo cleavage characteristics and chromosome constitution were related to PN morphology. Embryos developing from zygotes with the normal PN pattern (pattern 0) cleaved faster and formed embryos with better morphology as compared with zygotes with abnormal PN patterns. Aneuploidy rate of embryos derived from zygotes with the normal PN pattern, with a single PN anomaly and with a double PN anomaly was 25.6, 73 and 83% respectively. Chromosomally normal embryos with the normal PN pattern progressed to the blastocyst stage at a higher rate (90%) than chromosomally normal embryos with a single (61%) or a double (40%) PN anomaly. The same relationship applied to chromosomally abnormal embryos. It is concluded that PN morphology predicts both the risk of embryo developmental arrest and that of chromosomal abnormalities.

Blastocyst↗
PubMed2003

Outcome of blastocyst transfer according to availability of excess blastocysts suitable for cryopreservation.

The purpose of this study was to assess the outcome of blastocyst transfer in relation to the presence or absence of excess blastocysts available for cryopreservation. The study was designed as a retrospective case series in a tertiary care private hospital. The study group consisted of 450 blastocyst stage embryo transfer cycles. In 139 cycles there were excess freezeable blastocysts (group 1), in 78 cycles there were excess but unfreezeable blastocysts (group 2), and in 233 cycles there were no excess blastocysts (group 3). A mean of three blastocysts was replaced in all groups. Treatment cycle characteristics, implantation and pregnancy rates following fresh and cryopreserved blastocyst transfer were assessed in each group. More embryos reached the blastocyst stage in group 1 and more blastocysts were of good quality. In group 1, clinical pregnancy and implantation rates (71 and 41%) were significantly higher compared with groups 2 (56 and 27%) and 3 (43 and 19%). Embryos that were selected for transfer among a cohort of good quality blastocysts yielded the highest implantation and pregnancy rates. Given a clinical pregnancy rate of 71%, an implantation rate per embryo of 41%, and a multiple pregnancy rate of 58%, serious consideration should be given to a single blastocyst transfer in these patients.

Abortion, Spontaneous↗
PubMed2003

Embryo culture as a diagnostic tool.

Embryo culture can serve as a strong diagnostic tool, yielding useful information regarding the implantation potential of the human embryo. The information thus gained is useful for quality control of the embryology laboratory, success rates of the IVF/intracytoplasmic sperm injection (ICSI) programme, and counselling of the couple following failed cycles. Zygotes can be scored and zygote quality has been associated with further embryonic development and cleavage stage embryo quality. Early cleavage, cleavage rate, cleavage stage embryo grade and subsequent progression of these embryos to the blastocyst stage have all been shown to be individual and collective markers for the implantation-competent human embryo. This manuscript discusses embryonic markers of normality/quality throughout in-vitro culture starting with the zygote and ending with the blastocyst.

Animals↗
PubMed2002

Zona-intact versus zona-free blastocyst transfer: a prospective, randomized study.

OBJECTIVE: To compare the outcome of zona-intact versus zona-free blastocyst transfer. DESIGN: Prospective, randomized study. SETTING: Tertiary care private hospital IVF center. PATIENT(S): A total of 240 patients undergoing blastocyst stage ET (119 zona intact and 121 zona free). INTERVENTION(S): In vitro culture of embryos to the blastocyst stage was followed by random allocation to zona-intact or zona-free transfer. MAIN OUTCOME MEASURE(S): Treatment cycle characteristics, implantation, and pregnancy rates. RESULT(S): Transfer of zona-free blastocysts was associated with a higher implantation rate. Subgroup analysis, however, indicated that better outcome was achieved only in the group that received poor-quality blastocysts. Patients undergoing blastocyst transfer for the first time did not seem to benefit from zona-free blastocyst transfer. CONCLUSION(S): Zona-free blastocyst transfer increases the success of blastocyst-stage transfer in patients with poor-quality blastocysts.

Adult↗