P-213 The effects of vitrified embryos transported on IVF clinical outcomes: one center experience
Authors: Pellegrini L , De Angelis F , Tartaglia S , Toschi M , Galliano D , Pellicer A , Cozzolino M 
Published: June 2023

Abstract

Study question
Does the transportation of vitrified embryos affect the survival rate and in vitro fertilization (IVF) outcomes compared to those produced on-site?

Summary answer
The regulated transport of cryopreserved embryos has shown no detrimental effects on embryo survival rate or pregnancy outcomes.

What is known already
Reproductive medicine has substantially evolved in the last decades. A growing number of patients have stored gametes or embryos following IVF treatments; contemporary innovations in cryopreserving techniques revolutionized the IVF laboratory. However, the IVF industry is changing; clinics worldwide are merging with larger international companies, and patients choose to travel abroad for fertility treatments, which requires the movement of cryopreserved embryos over long distances. So far, no exhaustive evidence has been provided regarding the possible detrimental effects on cryopreserved embryos due to their transportation.

Study design, size, duration
This retrospective observational study assessed the outcomes of 608 single frozen embryo transfers at Instituto Valenciano de Infertilidad (IVI) Rome (Italy) between February 2021 and March 2022, assessing survival and IVF outcomes.

Participants/materials, setting, methods
Data from N = 608 patients undergoing frozen embryo transfer (FET) from autologous or donated oocytes were analysed. Single blastocysts transferred at IVI Rome (Group A, n = 440), were compared to those generated and vitrified at IVI Spain clinics, and subsequently transported to IVI Rome (Group B, n = 168). The transport system was managed by the same truck company. Frozen embryos from abroad were rigorously checked and later thawed by a team of expert embryologists.

Main results and the role of chance
Analysis of baseline population characteristics showed a significant difference in female patients’ age between Group A and Group B (39.78 ± 5.16 vs 42.47 ± 4.70; p &lt; 0.01). The highest incidence of heterologous cycles was in Group B (45.4% vs 82.14%; p &lt; 0.01). No significant differences were found between the age of the oocyte donors, male partners, or the patients’ BMI. Considering IVF outcomes, we found no statistically significant difference comparing Group A and B respectively for embryo survival rates after thawing (N = 430/440, 97.7% vs. N = 165/168, 98.21%, p = 0.71), pregnancy rate (N = 221/440, 50.23% vs. N = 77/168, 45.83%, p = 0.33), clinical pregnancy rate (N = 200/440, 45.45% vs. N = 62/168, 36.90%, p = 0.06), and cumulative miscarriage rate (N = 42/221, 19,00% vs. 22/77, 28.57%, p = 0.07). The sub-analysis considering embryos screened for aneuploidies using preimplantation genetic testing for aneuploidies (PGT-A) showed no statistical differences across the different groups. The logistic regression analysis showed that PGT, semen parameters, endometrial thickness, type of endometrial preparation and age, do not affect embryo survival and IVF outcomes.

Limitations, reasons for caution
The retrospective nature was the principal limitation. One single fertility Company (IVI-RMA) and its network have been considered, which could bias the results, although we employed different clinics in two different countries.

Wider implications of the findings
Regulated transport of vitrified human embryos between clinics in different countries are safe and reliable, with no adverse effects on embryo survival after thawing and IVF outcomes following FET. Embryo transportation did not affect embryo implantation potential, offering opportunities for patients to transfer biological samples within different laboratories.

Trial registration number
not applicable