Michael Dahan

Dr. Michael Dahan

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Research Focus & Metrics

Academic Career Length

27Years (2000-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 April 2013 in Human Reproduction
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Journal Article
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ASAyse Seyhan
Ayse Seyhan
BABaris Ata
Baris Ata
MPMehtap Polat
Mehtap Polat
WSWeon-Young Son
Weon-Young Son
HYHakan Yarali
Hakan Yarali
Michael DahanMichael Dahan
Michael Dahan
Is severe early ovarian hyperstimulation syndrome (OHSS) completely prevented with the GnRH agonist trigger and 1500 IU hCG luteal rescue protocol? Severe early OHSS can occur even after the GnRH agonist trigger and 1500 IU hCG luteal rescue protocol. Prior studies including over 200 women who received the GnRH agonist trigger and 1500 hCG luteal rescue protocol have reported complete prevention of severe early OHSS. Only a few late OHSS cases have been reported and it has been suggested that this protocol can be safely applied to any women under risk. This retrospective cohort study included all women who were at high risk of OHSS and were given the GnRH agonist trigger plus hCG luteal rescue protocol between December 2008 and August 2012 in the two participating centers. There were 23 women with a mean estradiol level of 4891 ± 2214 pg/ml and a mean number of >12 mm follicles of 20 ± 6 on the day of ovulation triggering. OHSS was categorized according to the Golan criteria. Overall 6 of the 23 (26%) women developed severe OHSS. Five women had severe early OHSS requiring ascites drainage and hospitalization and three of these women did not undergo embryo transfer. The number of follicles measuring 10–14 mm on the day of triggering was significantly different between women who developed severe early OHSS and those who did not. The small number of women with severe early OHSS may have prevented identification of other significant risk factors. Although the GnRH agonist plus 1500 IU hCG luteal rescue protocol significantly decreases the risk of severe OHSS, this life threatening complication can still occur in high-risk patients. It would be prudent to avoid hCG luteal rescue and freeze all embryos for future transfer in such women particularly when there are ≥18 follicles with 10–14 mm diameters even with few larger follicles. No funding was sought for this report. The authors have no conflict of interest to declare.

16 November 2016 in Human Reproduction
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Journal Article
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STSamer Tannus
Samer Tannus
WSWeon-Young Son
Weon-Young Son
AGAshley Gilman
Ashley Gilman
GYGrace Younes
Grace Younes
TSTal Shavit
Tal Shavit
Michael DahanMichael Dahan
Michael Dahan
Does ICSI improve reproductive outcomes compared with conventional IVF when used for non-male factor infertility in women aged 40 years and over? There is no advantage of ICSI over conventional IVF in women aged 40 years and over when used for non-male factor infertility. The use of ICSI has increased dramatically in recent years and is being applied for indications other than male factor infertility. Currently, ICSI is used in 65% of IVF cycles in Europe and in 76% of cycles in the USA. Despite its increase use, there is no clear evidence of a benefit in using ICSI over conventional IVF. Older women undergoing infertility treatments are at an increased risk of having diminished ovarian reserve and lower oocyte quality, which could make ICSI the preferred insemination method in this group. However, studies that have examined the benefits of ICSI in this age group are lacking. A retrospective, single center study included women, aged 40–43 years, who underwent IVF treatments for non-male factor infertility between January 2012 until June 2015. A total of 745 women were included in the study. Of these, 490 women underwent ICSI and 255 women underwent conventional IVF. In order to be included in the study, women had to be at least 40 years of age at the beginning of ovarian stimulation and their male partner had to have normal sperm parameters according to World Health Organisation (WHO) fifth edition. Exclusion criteria included: more than three previous IVF cycles, a history of fertilization failure or low fertilization (<50%), the use of donor or frozen oocytes and the use of donor or frozen sperm samples. The primary outcome was the live birth rate. Secondary outcomes included fertilization rates, fertilization failure and embryo quality. Baseline characteristics were similar between the two groups, except for the number of previous IVF cycles, which was higher in the ICSI group (1.0 vs. 0.6, P = 0.0001). Despite similar numbers of oocytes retrieved (7.2 vs. 6.5), when examining oocytes maturity (performed 2 h after oocyte retrieval in the ICSI group and after 18 h in the conventional IVF group), the conventional IVF group had a higher number of Metaphase II (MII) oocytes (6.1 vs. 4.7, P < 0.0001). The conventional IVF group also had higher numbers of zygotes formed (4.48 vs. 3.66, P = 0.001), more cycles with embryos transferred at the blastocyst stage (36 vs. 26%, P = 0.005) and more cycles where embryos were available for cryopreservation (26.4 vs. 19.7%, P = 0.048), compared with the ICSI group. The fertilization rates (64 vs. 67%) and fertilization failure (9.0 vs. 9.7%) were similar. After logistic regression analysis controlling for confounders, the live birth rates were similar between the groups (11.9 vs. 9.6%). Subgroup analyses of women undergoing their first IVF cycle and women with ≤3 oocytes retrieved did not show an advantage of ICSI over conventional IVF. The retrospective nature of this study was a major limitation. The ICSI group had a higher number of previous IVF cycles, which could mean that ICSI was performed in poorer prognosis patients. Moreover, although this study is one of the largest studies to examine the question of whether ICSI is of value for older women with non-male factor infertility, based on a post hoc power analysis, it was still underpowered to detect differences in live birth rates, which can limit the conclusions of the study. Prospective studies are needed to confirm our findings. The decision regarding performing ICSI should be based on sperm parameters and previous history. The use of ICSI for the sole indication of advanced maternal age shows no benefit over conventional IVF. None. N/A.

13 May 2020 in Reproductive Biology and Endocrinology
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OGon behalf of the POSEIDON (Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number) group
on behalf of the POSEIDON (Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number) group
CACarlo Alviggi
Carlo Alviggi
Sandro EstevesSandro Esteves
Sandro Esteves
Raoul OrvietoRaoul Orvieto
Raoul Orvieto
ACAlessandro Conforti
Alessandro Conforti
FUFilippo M. Ubaldi
Filippo M. Ubaldi
The prolonged lockdown of health services providing high-complexity fertility treatments –as currently recommended by many reproductive medicine entities– is detrimental for society as a whole, and infertility patients in particular. Globally, approximately 0.3% of all infants born every year are conceived using assisted reproductive technology (ART) treatments. By contrast, the total number of COVID-19 deaths reported so far represents approximately 1.0% of the total deaths expected to occur worldwide over the first three months of the current year. It seems, therefore, that the number of infants expected to be conceived and born –but who will not be so due to the lockdown of infertility services– might be as significant as the total number of deaths attributed to the COVID-19 pandemic. We herein propose remedies that include a prognostic-stratification of more vulnerable infertility cases in order to plan a progressive restart of worldwide fertility treatments. At a time when preventing complications and limiting burdens for national health systems represent relevant issues, our viewpoint might help competent authorities and health care providers to identify patients who should be prioritized for the continuation of fertility care in a safe environment.

21 June 2018 in Journal of Turkish Society of Obstetric and Gynecology
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Journal Article
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ŞHŞafak Hatırnaz
Şafak Hatırnaz
BABarış Ata
Barış Ata
EHEbru Saynur Hatırnaz
Ebru Saynur Hatırnaz
Michael DahanMichael Dahan
Michael Dahan
STSamer Tannus
Samer Tannus
STSeang Lin Tan
Seang Lin Tan
In vitro maturation (IVM) is one of the most controversial aspects of assisted reproductive technology. Although it has been studied extensively, it is still not a conventional treatment option and is accepted as an alternative treatment. However, studies have shown that IVM can be used in almost all areas where in vitro fertilization (IVF) is used and it has a strong place in fertility protection and Ovarian Hyperstimulation syndrome management. The aim of this systematic review was to address all aspects of the current knowledge of IVM treatment together with the evolution of IVM and IVF.

9 May 2016 in Human Reproduction
Verified
Journal Article
Open access
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Michael DahanMichael Dahan
Michael Dahan
STSeang Lin Tan
Seang Lin Tan
JCJintae Chung
Jintae Chung
WSWeon-Young Son
Weon-Young Son
In vitro maturation (IVM) of human oocytes is a reproductive technique which has been practiced for 25 years and is gaining popularity. However, the techniques used for IVM differ substantially across clinics and they result in extremely variable pregnancy rates, partially due to some of these differences in protocols. Such differences include the use in some cycles of hCG triggering prior to oocyte retrieval and the use of a few days of gonadotrophin treatment to support moderate follicle growth. Other important factors are patient selection (including those with polycystic ovaries or decreased ovarian reserve), the number of embryos transferred and cleavage-stage embryo or blastocyst transfer. There are also substantial differences of opinion among clinicians regarding IVM and what it implies. Due to the large variation in protocols, a decision was made to write this paper in an attempt to introduce uniformity when comparing treatments and outcomes of IVM. A clinical definition of IVM was developed: The retrieval of oocytes from small and intermediate sized follicles in an ovary before the largest follicle has surpassed 13 mm in mean diameter. The use of short gonadotrophin stimulation should be acknowledged. However, it should be stated that metaphase II oocytes also have the potential to be collected at that time in the cycles associated with either hCG or GnRH agonist priming. Many feel this is not IVM because some mature oocytes are retrieved, therefore, we recommend renaming this procedure either natural cycle IVF or modified natural cycle IVF (if gonadotrophin stimulation is given) with early triggering, combined with IVM. The percentage as well as the absolute number of mature oocytes at retrieval should be indicated. The use of these titles will allow transparency when comparing results of IVM cycles.

17 July 2019 in Frontiers in Endocrinology
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Journal Article
Open access
WSWeon-Young Son
Weon-Young Son
SHSara Henderson
Sara Henderson
YCYoni Cohen
Yoni Cohen
Michael DahanMichael Dahan
Michael Dahan
WBWilliam Buckett
William Buckett
In vitro maturation (IVM) of human immature oocytes has been offered to women who are at risk of developing ovarian hyperstimulation syndrome (OHSS) caused by gonadotropin stimulation, such as PCO(S) patients or who have poor ovarian reserve. Cryopreservation of oocytes matured in vivo obtained in IVF cycles has improved after implementing the vitrification method and many successful results have been reported. Now, this procedure can be successfully offered to fertility preservation programs for patients who are in danger of losing their ovarian function due to medical or social reasons, and to oocyte donation programs. This vitrification technique has also been applied to cryopreserve oocytes obtained from IVM program. Some advantages of oocytes vitrification related with IVM are: (1) eliminating costly drugs and frequent monitoring; (2) completing treatment within 2 to 10 days (3) avoiding the use of hormones in cancer patients with hormone-sensitive tumors; and (4) retrieving oocytes at any point in menstrual cycle, even in the luteal phase. In addition, immature oocytes can also be collected from extracorporeal ovarian biopsy specimens or ovaries during caesarian section. Theoretically, there are two possible approaches for preserving immature oocytes: oocyte cryopreservation at the mature stage (after IVM) and oocyte cryopreservation at the Germinal Vesicle (GV)-stage (before IVM). Both vitrification of immature oocyte before/after IVM is not currently satisfactory. Nevertheless, many IVF centers worldwide are doing IVM oocyte cryopreservation as one of the options to preserve fertility for female cancer. Therefore, more studies are urgently required to improve IVM- and vitrification method to successfully preserve oocytes collected from cancer patients. In this review, present oocyte maturation mechanisms and recent progress of human IVM cycles will be discussed first, followed by some studies of the vitrification of human IVM oocyte.