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Dive into the research topics where Kayhan Yakin is active.

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Featured researches published by Kayhan Yakin.


Reproductive Biomedicine Online | 2011

Clinical outcome of intracytoplasmic injection of spermatozoa morphologically selected under high magnification: a prospective randomized study

Basak Balaban; Kayhan Yakin; Cengiz Alatas; Ozgur Oktem; Aycan Isiklar; Bulent Urman

Recent evidence shows that the selection of spermatozoa based on the analysis of morphology under high magnification (×6000) may have a positive impact on embryo development in cases with severe male factor infertility and/or previous implantation failures. The objective of this prospective randomized study was to compare the clinical outcome of 87 intracytoplasmic morphologically selected sperm injection (IMSI) cycles with 81 conventional intracytoplasmic sperm injection (ICSI) cycles in an unselected infertile population. IMSI did not provide a significant improvement in the clinical outcome compared with ICSI although there were trends for higher implantation (28.9% versus 19.5%), clinical pregnancy (54.0% versus 44.4%) and live birth rates (43.7% versus 38.3%) in the IMSI group. However, severe male factor patients benefited from the IMSI procedure as shown by significantly higher implantation rates compared with their counterparts in the ICSI group (29.6% versus 15.2%, P=0.01). These results suggest that IMSI may improve IVF success rates in a selected group of patients with male factor infertility. New technological developments enable the real time examination of motile spermatozoa with an inverted light microscope equipped with high-power differential interference contrast optics, enhanced by digital imaging. High magnification (over ×6000) provides the identification of spermatozoa with a normal nucleus and nuclear content. Intracytoplasmic injection of spermatozoa selected according to fine nuclear morphology under high magnification may improve the clinical outcome in cases with severe male factor infertility.


Reproductive Biomedicine Online | 2005

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

Bulent Urman; Kayhan Yakin; Basak Balaban

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.


Human Reproduction | 2009

Luteal phase empirical low molecular weight heparin administration in patients with failed ICSI embryo transfer cycles: a randomized open-labeled pilot trial

Bulent Urman; Baris Ata; Kayhan Yakin; Cengiz Alatas; Senai Aksoy; Ramazan Mercan; Basak Balaban

BACKGROUND The pathology underlying recurrent implantation failures (RIF) is not clear and treatment options proposed are generally not evidence based. Although the effect of heparin on trophoblast biology has not been studied extensively, given the available data suggesting a possible beneficial effect of heparin on embryo implantation, we decided to undertake this pilot study. METHODS One hundred and fifty women with > or =2 failed assisted reproduction treatment cycles were included in this randomized open-label pilot trial. Participants underwent controlled ovarian stimulation with the long protocol and were randomly allocated to receive 1 mg/kg/day low molecular weight heparin (LMWH) or no treatment in addition to routine luteal phase support (LPS) on the day after oocyte retrieval. LPS and LMWH was continued up to the 12th gestational week in pregnant participants. RESULTS There were 26 (34.7%) live births in the LMWH group, and 20 (26.7%) in the control group (absolute difference 8.0%, 95% CI -4.2 to 24.9%, P = 0.29). There were 34 (45.3%) and 29 (38.7%) clinical pregnancies in the LMWH and control groups, respectively (absolute difference 6.6%, 95% CI -9.0 to 21.8%, P = 0.41). Implantation rates were 24.5 and 19.8% in the LMWH and control groups, respectively (absolute difference 4.7%, 95% CI -4.7 to 14.1%, P = 0.33). CONCLUSION Despite lack of statistical significance, observed relative increase by 30% in live birth rates with LMWH may be regarded as a clinically significant trend necessitating further research on the use of empirical LMWH in women with RIF and possibly in all women undergoing assisted reproduction treatment. Failure to demonstrate statistical significance of the observed treatment difference may be due to limited sample size of this pilot study.


Reproductive Biomedicine Online | 2005

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

Bulent Urman; Kayhan Yakin; Basak Balaban

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.


Reproductive Biomedicine Online | 2004

Pronuclear morphology predicts embryo development and chromosome constitution

Basak Balaban; Kayhan Yakin; Bulent Urman; Aycan Isiklar; Jan Tesarik

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.


Reproductive Biomedicine Online | 2013

Removal of unilateral endometriomas is associated with immediate and sustained reduction in ovarian reserve.

Bulent Urman; Ebru Alper; Kayhan Yakin; Ozgur Oktem; Senai Aksoy; Cengiz Alatas; Ramazan Mercan; Baris Ata

Endometrioma surgery by stripping the cyst capsule has been associated with a reduction in ovarian reserve. It is still not clear whether the inflicted damage is immediate, sustained over time or associated with the use of electrocautery, nor which marker is more accurately reflects the post-operative reduction in ovarian reserve. This observational study assessed the damage inflicted by endometrioma removal with anti-Müllerian hormone (AMH) concentration and antral follicle count (AFC) pre and post-operatively. Twenty-five women with unilateral endometrioma underwent laparoscopic stripping of the endometrioma cyst capsule. There was a significant decrease both in AMH concentration (24%) and in AFC (11%) 1 month following surgery (P<0.01). At 6months post-operatively, the respective values were 24% and 15% less than preoperatively. AMH concentration and AFC showed no correlation with the use of bipolar electrocautery during surgery. Primordial follicles embedded adjacent to the cyst capsule were found in 61.5% of the specimens. Endometrioma surgery by stripping of the cyst capsule is associated with a significant reduction in ovarian reserve. The reduction is immediate and sustained over time. AMH appears to be a better indicator for post-operative quantification of the ovarian reserve.


Human Reproduction | 2008

GnRH agonist protocol administration in the luteal phase in ICSI - ET cycles stimulated with the long GnRH agonist protocol: a randomized, controlled double blind study

Baris Ata; Kayhan Yakin; Basak Balaban; Bulent Urman

BACKGROUND GnRH agonist administration in the luteal phase was reported to beneficially affect the clinical outcome of intracytoplasmic sperm injection (ICSI) and embryo transfer (ET) cycles. This double blind, randomized, placebo controlled trial evaluates whether a single dose GnRH agonist administered 6 days after ICSI increases ongoing pregnancy rates following ET in cycles stimulated with the long GnRH agonist protocol. METHODS Five hundred and seventy women undergoing ET following controlled ovarian stimulation with a long GnRH agonist protocol were included. In addition to routine luteal phase support with progesterone, women were randomized to receive a single 0.1 mg dose of triptorelin or placebo 6 days after ICSI. Randomization was done on the day of ET according to a computer generated randomization table. Ongoing pregnancy rate beyond 20th week of gestation was the primary outcome measure. The trial was powered to detect a 12% absolute increase from an assumed 38% ongoing pregnancy rate in the placebo group, with an alpha error level of 0.05 and a beta error level of 0.2. RESULTS There were 89 (31.2%) ongoing pregnancies in the GnRH agonist group, and 84 (29.5%) in the control group (absolute difference +1.7%, 95% confidence interval -5.8% to +9.2%). Implantation, clinical pregnancy and multiple pregnancy rates were likewise similar in the GnRH agonist and placebo groups. CONCLUSIONS Single 0.1 mg triptorelin administration 6 days after ICSI following ovarian stimulation with the long GnRH agonist protocol does not seem to result in an increase >or=12% in ongoing pregnancy rates.


International Journal of Urology | 2005

Is there a possible correlation between chromosomal variants and spermatogenesis

Kayhan Yakin; Basak Balaban; Bulent Urman

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.


Human Reproduction | 2008

Severe cytoplasmic abnormalities of the oocyte decrease cryosurvival and subsequent embryonic development of cryopreserved embryos

Basak Balaban; Baris Ata; Aycan Isiklar; Kayhan Yakin; Bulent Urman

BACKGROUND Abnormalities of oocyte morphology affect embryo quality and viability. Whether morphological abnormalities of the oocyte influence cryosurvival and further development of derived embryos is not known. The aim of this study was to compare cryosurvival and progression to the blastocyst stage of frozen-thawed embryos derived from normal and abnormal oocytes. METHODS A total of 5292 Grade 1 and 2 embryos from 964 women were frozen, thawed and subsequently cultured up to the blastocyst stage. The study was performed on excess embryos from patients who did not opt for cryopreservation. Cryosurvival, progression to the blastocyst stage and hatching were correlated with morphological characteristics of the oocytes that embryos were derived from. RESULTS Presence of a cytoplasmic abnormality of the oocyte significantly decreased cryosurvival. This detrimental effect was more pronounced in embryos derived from oocytes with vacuolar cytoplasm or with central granulation. Furthermore, these embryos did not have the potential to develop into good quality blastocysts or reach the hatching stage. On the other hand, presence of a single extracytoplasmic abnormality of the oocyte did not affect cryosurvival and the potential to develop into good quality blastocysts. Grade 2 embryos derived from oocytes with irregular shape or a large perivitelline space had decreased cryosurvival. However when these embryos survived cryopreservation, their potential to develop good quality blastocysts or to reach hatching stage was unaffected. CONCLUSIONS Embryos derived from oocytes with vacuolar cytoplasm or central granulation do not seem to bear the potential to develop good quality blastocysts or to reach hatching stage after cryopreservation. The presence of extracytoplasmic abnormalities alone does not affect blastocyst development despite decreasing cryosurvival.


Human Reproduction | 2011

DHEA as a miracle drug in the treatment of poor responders; hype or hope?

Kayhan Yakin; Bulent Urman

Dehydroepiandrosterone (DHEA) is being presented as a miracle-drug for the treatment of women responding poorly to gonadotrophin stimulation, while the debate on its actual effectiveness is still ongoing. We would like to present how insufficient the current evidence of acceptable quality is to warrant a conclusion that DHEA supplementation is an effective treatment for women with diminished ovarian reserve. We believe that large-scale, well-designed confirmatory studies are necessary to prove the efficacy of DHEA before it can be recommended for routine use.

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Ramazan Mercan

Eastern Virginia Medical School

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Yilmaz Guzel

Istanbul Aydın University

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