Blastocyst culture using single versus sequential media in clinical IVF: a systematic review and meta-analysis of randomized controlled trials.
PURPOSE
The purpose of this study was to undertake a review of the available evidence comparing the use of a single medium versus sequential media for embryo culture to the blastocyst stage in clinical IVF.


METHODS
We searched the Cochrane Central, PubMed, Scopus, ClinicalTrials.gov, Current Controlled Trials and WHO International Clinical Trials Registry Platform to identify randomized controlled trials comparing single versus sequential media for blastocyst culture and ongoing pregnancy rate. Included studies randomized either oocytes/zygotes or women. Eligible oocyte/zygote studies were analyzed to assess the risk difference (RD) and 95 % confidence intervals (CI) between the two media systems; eligible woman-based studies were analyzed to assess the risk ratio (RR) and 95 % CI for clinical pregnancy rate.


RESULTS
No differences were observed between single and sequential media for either ongoing pregnancy per randomized woman (relative risk (RR) = 0.9, 95 % CI = 0.7 to 1.3, two studies including 246 women, I 2 = 0 %) or clinical pregnancy per randomized woman (RR = 1.0, 95 % CI = 0.7 to 1.4, one study including 100 women); or miscarriage per clinical pregnancy: RR = 1.3, 95 % CI = 0.4 to 4.3, two studies including 246 participants, I 2 = 0 %). Single media use was associated with an increase blastocyst formation per randomized oocyte/zygote (relative distribution (RD) = +0.06, 95 % CI = +0.01 to +0.12, ten studies including 7455 oocytes/zygotes, I 2 = 83 %) but not top/high blastocyst formation (RD = +0.05, 95 % CI = -0.01 to +0.11, five studies including 3879 oocytes/zygotes, I 2 = 93 %). The overall quality of the evidence was very low for all these four outcomes.


CONCLUSIONS
Although using a single medium for extended culture has some practical advantages and blastocyst formation rates appear to be higher, there is insufficient evidence to recommend either sequential or single-step media as being superior for the culture of embryos to days 5/6. Future studies comparing these two media systems in well-designed trials should be performed.
['Sfontouris|Ioannis A|IA|', 'Martins|Wellington P|WP|', 'Nastri|Carolina O|CO|', 'Viana|Iara G R|IG|', 'Navarro|Paula A|PA|', 'Raine-Fenning|Nick|N|', 'van der Poel|Sheryl|S|', 'Rienzi|Laura|L|', 'Racowsky|Catherine|C|http://orcid.org/0000-0002-8961-7896']
D000328:Adult D001755:Blastocyst D002970:Cleavage Stage, Ovum D046149:Embryo Culture Techniques D004624:Embryo Transfer D047108:Embryonic Development D005260:Female D005307:Fertilization in Vitro D006801:Humans D050498:Live Birth D009865:Oocytes D011247:Pregnancy D018873:Pregnancy Rate D016032:Randomized Controlled Trials as Topic
Blastocyst Culture Single Sequential Medium Extended