Objective: To determine whether day 3 embryos exhibiting early compaction have an improved implantation potential compared to embryos without compaction.
Design: A retrospective cohort study.
Setting: Hospital-based academic medical center.
Patient(s): Women <38 years of age undergoing IVF cycles between November 2001 and December 2004 having a day 3 transfer of one or two embryos with >8 cells.
Intervention(s): Standard IVF protocol.
Main outcome measure(s): Compaction grading and implantation rates of 1,047 embryos as related to fragmentation of >or= 8-cell embryos in patients with either 0% or 100% implantation.
Result(s): Compaction grading was strongly associated with implantation potential; however, the direction of this effect depended on the degree of fragmentation. In embryos with <10% fragmentation, implantation rates increased with the degree of compaction (grade 1, 25%; grade 2, 33%; and grade 3, 47%); in embryos with >or=10% fragmentation, the effect was reversed (grade 1, 38%; grade 2, 20%; and grade 3, 9%).
Conclusion(s): Assessing the degree of compaction can be a valuable addition to traditional morphologic assessment in identifying optimal embryos for transfer on day 3.