Techniques for preparation prior to embryo transfer

Area of Science:

• Reproductive Medicine
• In Vitro Fertilisation (IVF)
• Embryo Transfer (ET) Techniques

Background:

• Embryo transfer (ET) is a critical step in in vitro fertilisation (IVF), with success rates potentially influenced by preparation techniques.
• Existing research on interventions like straightening the utero-cervical angle, cervical preparation, and cervix traversal methods is limited.
• This review aims to clarify the effectiveness and safety of these pre-ET preparation techniques.

Purpose of the Study:

• To systematically assess the benefits and harms of different preparation techniques employed before embryo transfer (ET).
• To evaluate interventions such as achieving a full bladder, removing cervical mucus, and using afterloading techniques for cervix traversal.
• To synthesize evidence from randomized controlled trials (RCTs) on their impact on IVF outcomes.

Main Methods:

• A comprehensive search of multiple databases (Cochrane Gynaecology and Fertility Group Register, CENTRAL, MEDLINE, Embase, PsycINFO) was conducted.
• Included were RCTs comparing specific ET preparation techniques: full bladder vs. empty bladder, mucus removal vs. no removal, and afterloading vs. direct ET.
• Data were critically appraised, extracted independently, and meta-analysis was performed where appropriate; results were presented narratively otherwise.

Main Results:

• Evidence for most preparation techniques is of low or very low certainty, requiring cautious interpretation.
• Straightening the utero-cervical angle (full bladder) showed uncertain effects on pregnancy and adverse events.
• Cervical mucus removal and embryo afterloading techniques demonstrated potential, but with limited or uncertain evidence regarding pregnancy rates and transfer difficulty.

Conclusions:

• The current evidence base is insufficient to recommend specific embryo transfer preparation techniques.
• No definitive implications for clinical practice can be drawn due to the low certainty of the evidence.
• There is a significant need for larger, well-designed studies with clear methodologies to evaluate these interventions.