How embryo retention affects assisted reproductive technology outcomes: a systematic review and meta-analysis

Area of Science:

• Reproductive Medicine
• Assisted Reproductive Technology (ART)
• Embryo Transfer (ET)

Background:

• Embryo retention (ER) during embryo transfer (ET) raises concerns regarding assisted reproductive technology (ART) outcomes.
• Technical difficulties in ET can compromise implantation and increase complications.

Purpose of the Study:

• To systematically review and meta-analyze the impact of retransferring retained embryos on ART outcomes.
• Key outcomes evaluated include clinical pregnancy rate (CPR), biochemical pregnancy rate (BPR), ectopic pregnancy rate (EP), miscarriage rate (MR), and live birth rate (LBR).

Main Methods:

• Systematic literature search of PubMed, Scopus, and Cochrane databases.
• Pooled Mantel-Haenszel odds ratios (OR) with 95% confidence intervals (CI) were calculated.
• Subgroup and sensitivity analyses were performed based on study design, ET technique, and risk of bias.

Main Results:

• Retransferring retained embryos significantly reduced CPR (OR ≈ 0.75) and LBR.
• A substantial increase in EP risk was observed (OR ≈ 2.36).
• Matched study designs and afterload ET techniques showed more pronounced negative effects.

Conclusions:

• Embryo retention negatively impacts ART success, decreasing pregnancy and live birth rates.
• ER elevates the risk of ectopic pregnancy, necessitating protocol refinement.
• Further research into ER mechanisms and prospective studies are needed to optimize management.