Obstet Gynecol Sci.  2013 May;56(3):182-189.

Clinical outcomes of vitrified-thawed embryo transfer using a pull and cut straw method

• Lim JG
• Heo YT
• Min SG
• Min BY
• Uhm SJ
• Kim NH

Abstract

OBJECTIVE
To compare the clinical outcomes of patients with vitrified-thawed embryos transferred using either the 0.25 mL straw method and the pull and cut straw (PNC) method. To evaluate the clinical outcomes of patients with transferred embryos that underwent assisted hatching at the cleaved embryo (day 3) or the blastocyst (day 5) stage.
METHODS
The study population consisted of women who underwent vitrified-warmed embryo transfer between May 2000 and December 2011 and assisted hatching was performed after warming of embryos. Cycles of thawing between assisted hatching treated and non treated groups were compared for survival and pregnancy rates.
RESULTS
The PNC vitrification method improved survival and pregnancy rates in partial lysed embryos. While assisted hatching did not affect the developmental and clinical pregnancy rates of the vitrified-warmed blastocyst group, it did increase the pregnancy rate of poor quality vitrified-warmed cleaved embryos.
CONCLUSION
These results suggest that PNC may increase the number of clinical pregnancies via the vitrification of both cleaved embryos and blastocysts. In addition, selective assisted hatching treatment of embryos that show a poor prognosis after warming may increase the rate of clinical pregnancy.

Keyword

Assisted hatching; Pull and cut straw; Vitrified-thawed embryo

MeSH Terms

Blastocyst
Embryo Transfer
Embryonic Structures
Female
Humans
Pregnancy
Pregnancy Rate
Prognosis
Vitrification

Figure

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  Fig. 1 Vitrification-warming of embryos using the modified cut standard straw (PNC) method and structure of conventional straw. (A) Day 3 human cleaved embryos (×40). (B) Shape of the PNC (×40). (C) Loaded embryos on the tip of the PNC with a minimum volume of vitrification solution (×40). (D) Warming of embryos in the PNC by holding the PNC with bare hands (×40). (E) Cultured embryos for 42 hours after warming (arrows indicate partial lysed cell) (×40). (F) Hatching embryos cultured for 66 hours after warming and assisted hatching (arrows indicate partially lysed cells) (×40). (G) Structure of conventional straw for embryo vitrification (VS, vitrification solution; S, sucrose) (×40).

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