Download High implantation and pregnancy rates with transfer of human

FERTILITY AND STERILITY威
VOL. 75, NO. 4, APRIL 2001
Copyright ©0 American Society for Reproductive Medicine
Published by Elsevier Science Inc.
Printed on acid-free paper in U.S.A.
High implantation and pregnancy rates with transfer
of human hatching day 6 blastocysts
Although improved outcomes of IVF after transfer of blastocysts has been reported (1, 2), it remains
uncertain which blastocyst can develop into a viable fetus. At present, expansion of the blastocyst is the most
practical selection criterion. However, if extended culture of embryos produces many expanded-stage
blastocysts, it is not easy to decide which blastocysts to transfer (Fig. 1A). In addition, some blastocysts fail
to hatch out of the zona, despite evidence that the blastocoelic cavity had expanded and the zona pellucida had
thinned (3).
We sought to investigate the rate of blastocyst formation and hatching on day 6 after insemination and to
assess the developmental potential of hatching or hatched blastocysts after transfer.
The study was approved by the institutional review board of Maria Infertility Center. One hundred
thirty-nine patients were recruited between March and July 1999. Patients were ⱕ40 years of age (mean
[⫾SD]age, 34.4 ⫾ 3.7 years) and had more than seven zygotes or two good-quality embryos on day 2. The
zygotes were co-cultured with cumulus cells for 120 hours in 10 ␮L of YS medium (Table 1) supplemented
with 10% human follicular fluid. All droplets for co-culture were exchanged for a preequilibrated culture
medium every morning until day 6. Embryo transfer was routinely performed on day 6.
Of 2,117 oocytes retrieved, 1,387 oocytes fertilized normally (65.5%). Of these, 757 (54.6%) developed
to the early blastocyst stage, 658 (47.4%) reached the expanding blastocyst stage, and 517 (37.3%) formed
expanded blastocysts. Hatching was observed in 174 blastocysts (12.5%), and 42 blastocysts (3.0%) of zygotes
could hatch on day 6 (Fig. 1B). A total of 281 blastocysts were transferred to 139 patients on day 6. Fifty-six
percent of the patients (78 cycles) had at least 1 hatching blastocyst for transfer, and a mean of 1.9 ⫾ 0.2
blastocysts were transferred.
Received July 31, 2000;
revised and accepted
October 5, 2000.
Presented at the Conjoint
Annual Meeting of the
American Society for
Reproductive Medicine and
Canadian Fertility and
Andrology Society,
Toronto, Ontario, Canada,
September 25–30, 1999.
Reprint requests: HyeGyun Yoon, M.Sc., In Vitro
Fertilization Laboratory,
Maria Infertility Clinic, 10311, Sinseol-dong,
Dongdaemun-gu, Seoul,
Korea (FAX: 82-2-2-2342505; E-mail: yoonhg@
yahoo.com).
0015-0282/⫺1900/$20.00
PII S0015-0282(00)01797-0
832
The implantation and pregnancy rates were significantly higher in patients who received one or more
hatching blastocysts than in patients who received nonhatching blastocysts (P⬍.05). The number of multiple
gestations was the same in both groups, despite replacement of fewer embryos in patients with hatching
blastocysts. The overall clinical pregnancy rate per transfer of blastocyst on day 6 was 48.9%, and the
implantation rate was 31.0%. The multiple gestation rate was 16.7%; no triplet gestations occurred.
Our results show that the chance of success in assisted reproduction can be improved if selection of the
most viable embryos is based on hatching status. After day 6 of culture, 23% (757 of 1,387) of blastocysts
were hatching naturally; this finding is in agreement with the data of Gardner et al. (4) (25% of blastocysts).
Under our culture conditions, 54.6% of zygotes developed to the blastocyst stage by day 6, and 37.3% formed
expanded blastocysts. These rates are similar to those reported with co-culture (5) and those obtained by using
a simple medium (1). YS medium was designed to support development of the human zygote to the blastocyst
under the cumulus cell co-culture system.
In conclusion, after 6 days of culture, at least one hatching blastocyst developed in more than 50% of
patients. An increased implantation rate was observed in patients who received hatching blastocysts, and no
triplet pregnancy occurred.
Hye-Gyun Yoon, M.Sc.a,b
San-Hyun Yoon, M.Sc.a
Weon-Young Son, Ph.D.a
Kyung-Soon Im, Ph.D.b
Jin-Ho Lim, M.D.a
In Vitro Fertilization Laboratory,a Maria Infertility Clinic, Seoul, and Department of Animal Science
and Technology,b Seoul National University, Suwon, Korea
FIGURE 1
Morphology of blastocysts cultured in vitro for 5 or 6 days
(original magnification, ⫻10). (A), Expanding and expanded
blastocysts formed on day 5. It was sometimes difficult to
select viable embryos for transfer. (B), Blastocysts that
reached the hatching (solid arrow) and hatched stage (open
arrow) on day 6. These morphologic distinctions may assist
in the selection of more viable embryos for transfer.
TABLE 1
Components of YS medium used for IVF and IVC.
Chemical
EDTA.2H2O
CaCl2䡠2H2O
NaCl
KCl
MgSO4䡠7H2O
Taurine
Na-Pyruvate
KHCO3
NaHCO3
L-Glutamine
Na-Lactate
Minimum nonessential medium
RPMI 1640 AA
Minimum essential medium
FW
mM
g/L
372.2
147
58.44
74.55
246.5
125.1
110
100.1
84.01
146.1
112.1
Gibco
Sigma
Gibco
0.05
1.8
110.0
5.0
0.8
0.2
0.4
5.0
20.0
1.2
3.0
—
—
—
0.0186
0.2646
6.2484
0.3728
0.1972
0.0250
0.0440
0.5005
1.6802
0.1753
0.5 mL
10 mL
10 mL
10 mL
Note: EDTA ⫽ ethylenediamine tetraacetic acid.
References
Yoon. Transfer of human hatched/hatching blastocysts. Fertil Steril 2001.
FERTILITY & STERILITY威
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