Impact of Endometrial Injury on IVF Outcomes Insights from the 2021 Cochrane Review
- OBGYN Library Team
- Aug 21
- 4 min read
Updated: Aug 22
In vitro fertilization (IVF) offers hope to many couples facing infertility, but success rates remain a challenge. One intervention that has attracted attention is endometrial injury, sometimes called "endometrial scratching," which involves intentionally causing a small injury to the uterine lining before embryo transfer. The idea is that this injury might improve the chances of embryo implantation and pregnancy. The 2021 Cochrane review by Lensen et al. provides a comprehensive analysis of the evidence on this topic. This post summarizes their key findings, explores the impact of endometrial injury on IVF outcomes, and discusses what this means for clinical practice and future research.
What Is Endometrial Injury and Why Is It Used in IVF?
Endometrial injury involves creating a small, controlled wound in the lining of the uterus, typically using a thin catheter or biopsy tool. This procedure is usually done in the cycle before embryo transfer or sometimes during the IVF cycle itself. The rationale is that the injury may trigger a local inflammatory response, releasing growth factors and cytokines that could enhance the receptivity of the endometrium to the embryo.
Clinicians have debated whether this intervention improves IVF success rates, especially for women who have experienced repeated implantation failure. The 2021 Cochrane review aimed to clarify the benefits and risks by analyzing randomized controlled trials (RCTs) on this practice.
Key Findings from the 2021 Cochrane Review
Lensen et al. reviewed 40 RCTs involving over 7,000 women undergoing IVF or intracytoplasmic sperm injection (ICSI). The trials compared outcomes between women who had endometrial injury and those who did not. Here are the main findings:
No Clear Benefit for General IVF Population
The review found no significant increase in live birth rates for women undergoing endometrial injury compared to controls.
The pooled live birth rate was 32% in the injury group versus 30% in the control group, a difference that was not statistically significant.
Clinical pregnancy rates and ongoing pregnancy rates also showed no meaningful improvement.
Possible Benefit in Women with Repeated Implantation Failure
Some subgroup analyses suggested a small benefit for women with a history of repeated implantation failure (defined as failure after at least two or three embryo transfers).
In this subgroup, live birth rates were modestly higher with endometrial injury, but the evidence was limited and inconsistent.
The review emphasized the need for more high-quality trials focused on this group.
Timing and Method of Injury Varied Widely
Studies differed in when the injury was performed: during the cycle before IVF, during ovarian stimulation, or at the time of egg retrieval.
The review found no clear evidence that timing influenced outcomes.
Methods of injury also varied, including pipelle biopsy and scratching with other instruments.
Safety and Side Effects
Endometrial injury was generally safe with few reported adverse effects.
Some women experienced mild discomfort or spotting after the procedure.
No serious complications were reported in the included trials.
Implications for Clinical Practice
The 2021 Cochrane review provides important guidance for fertility specialists and patients considering endometrial injury as part of IVF treatment.
Routine use of endometrial injury for all IVF patients is not supported by current evidence. The lack of clear benefit means it should not be standard practice.
Consideration may be given to women with repeated implantation failure, but only after discussing the limited and uncertain evidence.
Clinicians should inform patients about the potential risks, benefits, and the current state of research to support shared decision-making.
Given the variability in timing and technique, if endometrial injury is performed, it should follow protocols used in clinical trials to ensure safety and consistency.
Directions for Future Research
The review highlights several areas where further research is needed:
Focused trials on women with repeated implantation failure to clarify whether endometrial injury improves outcomes in this subgroup.
Standardization of timing and method of injury to identify the most effective approach if any benefit exists.
Long-term follow-up studies to assess any impact on maternal or neonatal health.
Investigation of biological mechanisms to better understand how endometrial injury might influence implantation.
Summary of Statistical Data
Outcome | Endometrial Injury Group | Control Group | Difference |
Live birth rate | 32% | 30% | Not statistically significant |
Clinical pregnancy rate | 38% | 36% | No significant difference |
Ongoing pregnancy rate | 30% | 29% | No significant difference |
Adverse events | Mild discomfort in 5-10% | Similar | No serious complications |
These numbers reflect pooled data from multiple trials and show that the overall impact of endometrial injury on IVF success is minimal.
Endometrial injury remains a debated intervention in IVF treatment. The 2021 Cochrane review by Lensen et al. provides strong evidence that it does not improve live birth rates for most women undergoing IVF. While there may be a small benefit for those with repeated implantation failure, this is not yet conclusive. Patients and clinicians should weigh the current evidence carefully before choosing this procedure. Future research will help clarify its role and potentially improve IVF outcomes for specific groups.
For those considering IVF, focusing on proven strategies and individualized care remains the best approach to maximize chances of success.
REFERENCE:
Lensen SF, Armstrong S, Gibreel A, Nastri CO, Raine-Fenning N, Martins WP. Endometrial injury in women undergoing in vitro fertilisation (IVF). Cochrane Database Syst Rev. 2021 Jun 10;6(6):CD009517. doi: 10.1002/14651858.CD009517.pub4. Update in: Cochrane Database Syst Rev. 2026 May 15;5:CD009517. doi: 10.1002/14651858.CD009517.pub5. PMID: 34110001; PMCID: PMC8190981.
FOR FURTHER RECOMMENDATIONS & GUIDELINES:
Comments