Optimal embryo transfer strategy in poor response may include freeze-all.
OBJECTIVE
In this retrospective cohort study, we investigated the best embryo transfer strategy in ICSI cycles with ≤4 oocytes collected at oocyte retrieval.


METHODS
Women who underwent antagonist co-treatment COS for ICSI treatment between January 2010 and December 2015 at a private ART clinic (N = 2263). Eight hundred seventy-nine women (group 1) had ≤4 oocytes collected at oocyte retrieval, of whom 645 (group A) had cleavage stage embryo transfer (ET), and 234 (group B) had blastocyst ET. One thousand three hundred eighty-four women (group 2) had 10-15 oocytes collected at oocyte retrieval, of whom 676 (group C) had cleavage stage ET, and 708 women (group D) had blastocyst ET. Blastocyst vitrification was performed using the Cryotop method and FET using artificial cycles.


RESULTS
In group 1, the cancellation rate was significantly lower in group A (25.2 vs 38 %). The pregnancy rate (PR), clinical PR, implantation rate (IR), and live birth rate (LBR) per ET and per oocyte retrieval were all lower in group A. The clinical PR, IR, and LBR per ET of vitrified-warmed blastocyst ET were significantly the highest. In group 2, the cycle cancellation rate was significantly lower in group C (3.5 vs 13.4 %). The PR, clinical PR, and IR per ET and per oocyte retrieval were all lower in group C. The LBR per ET was significantly lower, but the LBR per oocyte retrieval was not significantly lower in group C. Again, the PR, clinical PR, and IR per ET of vitrified-warmed blastocyst ET were significantly the highest.


CONCLUSIONS
Day 5 ET strategy has been reserved for normal or high responders. The improved pregnancy outcomes from blastocyst culture and cryopreservation may challenge ART to extend this benefit to poor responders.
Antalya IVF, Halide Edip Cd. No: 7, Kanal Mh, Antalya, 07080, Turkey. mberkkan@hotmail.com.
Murat
M
Berkkanoglu
Antalya IVF, Halide Edip Cd. No: 7, Kanal Mh, Antalya, 07080, Turkey.
Kevin
K
Coetzee
Antalya IVF, Halide Edip Cd. No: 7, Kanal Mh, Antalya, 07080, Turkey.
Hasan
H
Bulut
Antalya IVF, Halide Edip Cd. No: 7, Kanal Mh, Antalya, 07080, Turkey.
Kemal
K
Ozgur
D000328:Adult; D001755:Blastocyst / Q000166:cytology*; D015925:Cryopreservation; D010064:Embryo Implantation / Q000235:genetics; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D054315:Oocyte Retrieval / Q000379:methods; D009865:Oocytes / Q000254:growth & development*; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods; D058989:Vitrification
Blastocyst culture; Diminished ovarian reserve; Freeze-all; Poor response