***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: PGD ( preimplantation genetic diagnosis ) of aneuploidy for chromosomes X , Y , 13 , 18 and 21 was carried out on 196 embryos from 36 infertile patients classified with a poor prognosis due to ( i ) maternal age , ( ii ) repeated in-vitro fertilization ( IVF ) failures and ( iii ) mosaic karyotype . The percentage of abnormal embryos was comparable in the three groups of patients : maternal age 63 % , repeated IVF failure 57 % , and mosaic karyotype 62 % . The analysis of the overall data revealed an increased incidence of abnormal embryos in the older age categories ( predominantly due to aneuploidy ) , even in embryos at the 7- to 8-cell stage . In addition , the percentage of chromosomally abnormal embryos was directly proportional to the number of IVF failures , where the increase in chromosomal abnormalities was not correlated to aneuploidy but to other aberrations such as mosaicism and polyploidy . Following PGD , 28 patients had at least one embryo transferred that appeared normal by fluorescent in-situ hybridization ( FISH ) . Four clinical pregnancies result ed , with an implantation rate of 10 % per normal embryo . In conclusion , the high rate of chromosomally abnormal embryos in poor prognosis patients may have been the cause of implantation failure in their previous IVF cycles . Therefore , the possibility of transferring embryos with a normal FISH complement could improve the chance of pregnancy in this category of patients OBJECTIVE To assess the potential benefit of preimplantation aneuploidy testing on the outcome of  in vitro fertilization ( IVF ) for women of advanced maternal age ( AMA ) . DESIGN Prospect i ve r and omized clinical trial . SETTING Private IVF clinic . PATIENT(S ) Sixty-two infertile AMA couples undergoing fertility treatment . INTERVENTION(S ) Fluorescent in situ hybridization ( FISH ) for chromosomes X , Y , 13 , 15 , 16 , 17 , 18 , 21 , and 22 . MAIN OUTCOME MEASURE(S )  Preimplantation aneuploidy testing of biopsied blastomeres on day 3 of development . RESULT ( S ) Fertilization and blastocyst developmental rates were similar for the test and control groups : 80 % versus 77.4 % and 49 % versus 48.2 % , respectively . The average number of embryos transferred was comparable at 2.2 for the test group and 2.7 for the control group . Implantation rates were also equivalent across the two groups : 37.3 % in the control group versus 36.5 % in the test group . Nevertheless , the spontaneous abortion rate was observed to be lower for the test group : 25.9 % versus 32.26 % in the control group . This result ed in an observed increase in delivery rates for the test group : 78 % versus 67.74 % in the control group . CONCLUSION ( S ) Preimplantation aneuploidy testing does not appear to statistically significantly improve outcome parameters in infertile AMA patients ; however , a trend toward a decrease in the spontaneous abortion rate with a subsequent higher delivery rate was observed BACKGROUND Single-embryo transfer is a well-accepted strategy to avoid multiple pregnancies in an assisted reproductive technology ( ART ) programme . Besides the morphological quality and embryo kinetics up to the blastocyst stage , preimplantation genetic screening ( PGS ) of aneuploidy has been advocated as an adjuvant approach to select the embryo . METHODS Couples with a female partner younger than 36 were r and omly assigned to undergo transfer of a single blastocyst in a cycle with or without PGS using FISH for the chromosomes X , Y , 13 , 16 , 18 , 21 , 22 . RESULTS After the enrolment of 120 of the projected 447 patients in each group , study recruitment was terminated prematurely on the basis of futility . The observed live birth delivery rates after ART were 30.8 versus 30.8 % per r and omized patient , 34.6 versus 34.6 % per cycle initiated , 37.8 versus 37.0 % per aspirated cycle and 41.6 versus 43.5 % per embryo transfer for the control versus the PGS group , respectively , with absolute between-group differences ( 95 % CI ; P value ) of 0 % ( -11.7 to 11.7 ; P = 1.00 ) , 0 % ( -12.7 to 12.7 ; P = 1.00 ) , -0.8 % ( -14.2 to 12.7 ; P = 0.91 ) and 2.1 % ( -12.7 to 16.7 ; P = 0.79 ) , respectively . Even in this younger age group , only 61 % of the embryos had a normal diploid status . CONCLUSIONS The absence of a beneficial treatment effect in this r and omized clinical trial provides no arguments in favour of PGS to improve live birth delivery rate following single-embryo transfer in women under the age 36 . Clinical Trials.gov : NCT00670059 BACKGROUND The data are compiled from two multicentre , prospect ively r and omized studies on the effect of follicular fluid meiosis-activating sterol ( FF-MAS ) on human oocytes . The donated oocytes were exposed either to test doses of FF-MAS or to control solutions . The data from the control groups are presented with chromosomal status of the embryos correlated to embryo morphology . METHODS The study includes 144 r and omly selected donated human oocytes . The nucleus from each blastomere was fixed separately and fluorescence in-situ hybridization ( FISH ) using seven probes ( 13 , 16 , 18 , 21 , 22 , X and Y ) was performed . RESULTS Analysis of 103 pre-embryos containing 479 blastomeres result ed in 424 blastomeres with clear FISH signals . Of these blastomeres , 55 % were normal diploid and 45 % were abnormal . At a pre-embryonic level , 53 % were classified as normal containing > or=50 % normal blastomeres while 31 % of the pre-embryos were classified as uniformly normal . Abnormality rate was significantly increased in the pre-embryos with unevenly sized blastomeres and with increasing degree of fragmentation at 68 h after fertilization . Applying criteria for good embryo quality significantly increased the rate of chromosomally normal pre-embryos from 53 to 75 % . CONCLUSIONS The data demonstrate the high degree of genetic heterogeneity in a r and omly selected pool of donated pre-embryos from an IVF programme . Further , we found that uniformity of blastomere size , degree of fragmentation and cleavage kinetics reflect the cytogenetic status of the pre-embryo and are therefore important in the selection of pre-embryos OBJECTIVE To select chromosomally euploid embryos for transfer by analyzing single biopsied blastomeres using either fluorescence in situ hybridization ( FISH ) for chromosomes 13 , 16 , 18 , 21 , and 22 or comparative genomic hybridization ( CGH ) , which provides a full karyotype . DESIGN Prospect i ve observational study . SETTING A large IVF unit and the research laboratory of a hospital clinical genetics unit . PATIENT(S ) Twenty patients with recurrent implantation failure . INTERVENTION(S ) Ovarian stimulation and IVF by intracytoplasmic sperm injection ( ICSI ) , embryo biopsy , and embryo transfer . MAIN OUTCOME MEASURE(S ) Chromosome normality of biopsied blastomeres and implantation and clinical pregnancy rates . RESULT ( S ) Comparative genomic hybridization was able to identify many chromosomal abnormalities that would have been missed if those cells had been analyzed by FISH . The clinical pregnancy rate per transfer and implantation rate was 11 % and 7 % for embryos analyzed by FISH and 21 % and 15 % for embryos analyzed by CGH . CONCLUSION ( S ) Comparative genomic hybridization is more effective than FISH for identifying chromosomally normal embryos , which may result in a higher clinical pregnancy rate and implantation rate after embryo transfer BACKGROUND It is generally accepted that the age-related increased aneuploidy rate is correlated with reduced implantation and a higher abortion rate . Therefore , advanced maternal age ( AMA ) couples are a good target group to assess the possible benefit of preimplantation genetic diagnosis for aneuploidy screening ( PGD-AS ) on the outcome after assisted reproductive technology ( ART ) . METHODS A prospect i ve r and omized controlled clinical trial ( RCT ) was carried out comparing the outcome after blastocyst transfer combined with PGD-AS using fluorescence in situ hybridization ( FISH ) for the chromosomes X , Y , 13 , 16 , 18 , 21 and 22 in AMA couples ( aged > or = 37 years ) with a control group without PGD-AS .  From the 400 ( 200 for PGD-AS and 200 controls ) couples that were allocated to the trial , an oocyte pick-up was performed effectively in 289 cycles ( 148 PGD-AS cycles and 141 control cycles ) . RESULTS Positive serum HCG rates per transfer and per cycle were the same for PGD-AS and controls : 35.8 % ( 19.6 % ) [ % /per embryo transfer ( per cycle ) ] and 32.2 % ( 27.7 % ) , respectively ( NS ) . Significantly fewer embryos were transferred in the PGD-AS group than in the control group ( P<0.001 ) . The implantation rate ( with fetal heart beat ) was 17.1 % in the PGD-AS group versus 11.5 % in the control group ( not significant ; P=0.09 ) . We observed a normal diploid status in 36.8 % of the embryos . CONCLUSIONS This RCT provides no arguments in favour of PGD-AS for improving clinical outcome per initiated cycle in patients with AMA when there are no restrictions in the number of embryos to be transferred Blastocysts more commonly have a normal karyotype than cleavage-stage embryos do . Moreover , blastocysts have also made a metabolic transition from catabolism and recycling of the oocyte 's reserves and re sources , processes that fuel the first 3 days of cleavage . Although not all blastocysts are karyotypically equal , it is still to be determined to what extent a mosaic karyotype might be a normal feature among embryos , both at the cleavage stage and the blastocyst stage-- and when looking for karyotypic abnormalities by embryo biopsy might help the chance of implantation rather than harm it . It is also still impractical to look at all the chromosomes that can , through their aneuploidy , st and in the way of successful embryonic and fetal development . We report a r and omized clinical trial of blastocyst biopsy followed by preimplantation genetic screening ( PGS ) for aneuploidy using 5-colour FISH . The trial was suspended and then terminated early when we were unable to show an advantage for PGS . If we are correct in assuming that mitotic non-disjunction is common by the stage of the blastocyst ( and that it is much less ominous than meiotic non-disjunction ) , then further studies of effective  PGS  of blastocysts for aneuploidy require methods of analysis that cover all the chromosomes and can differentiate the triallelic and monoallelic states of meiotically derived aneuploidies from the biallelic state of mitotic aneuploidies OBJECTIVE The purpose of this study was to determine the positive predictive value ( PPV ) and negative predictive value ( NPV ) of FISH analysis and to determine which chromosomal abnormalities are most frequently confirmed . DESIGN Prospect i ve observational . SETTING IVF laboratory . PATIENT(S ) Two hundred forty-one embryos were analyzed from 98 patients . INTERVENTION(S ) FISH re analysis . MAIN OUTCOME MEASURE(S ) Embryos that would have been discarded in patients undergoing preimplantation genetic diagnosis ( PGD ) were fixed and FISH re analysis  was performed . Results of re analysis were compared with the day 3 diagnosis while PPV and NPV were calculated . RESULT ( S ) Among the 241 embryos , 198 embryos were abnormal and 43 were normal by day 3 FISH analysis . The PPV was 83 % and the NPV was 81 % . PPV was also determined for specific categories of aneuploidy , and certain abnormalities such as monosomies , trisomies , tetrasomies , and polyploidies were frequently confirmed on re analysis ( PPV > 80 % ) , whereas Turner syndrome diagnosis was not ( PPV = 17 % ) . CONCLUSION ( S ) FISH analysis offers a PPV of 83 % and NPV of 81 % when evaluating a single blastomere in conjunction with PGD . FISH errors and mosaicism are primarily responsible for 
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Discussion With currently available technology , and taking into account the number of embryos to be transferred , the clinical validity of PGS-FISH , although superior to that of morphological criteria , does not appear to be clinical ly relevant