🧬 Endometrial Scratching: Does the Evidence Support It in 2026?

Endometrial scratching (also called endometrial injury or endometrial biopsy for ART) was widely offered to IVF patients in the 2010s as an add-on intended to improve implantation rates. The procedure deliberately disrupts the uterine lining with a small biopsy catheter, on the theory that the resulting wound healing response would make the endometrium more receptive at the next embryo transfer.

The theory was attractive. The early evidence looked promising. And then the well-designed randomized controlled trials (RCTs) arrived — and they told a different story.

What the Procedure Involves

A thin flexible plastic catheter (typically a Pipelle de Cornier) is passed through the cervix and a small piece of endometrial tissue is sampled. The procedure is brief (a few minutes), generally done in the cycle preceding embryo transfer (often around cycle days 21 to 26 of the prior cycle), and feels similar to an IUD insertion or hysterosalpingogram — uncomfortable cramping for most patients.

The Early Enthusiasm: Small Studies

The initial 2003 paper by Barash et al. suggested a near doubling of implantation rates in women with repeated implantation failure. A wave of follow-up small studies and meta-analyses through the late 2000s and early 2010s continued to suggest benefit, particularly in women with prior IVF failure.

The SCRaTCH Trial: 2019

The SCRaTCH trial (Endometrial Scratch to Increase Live Birth Rate), published in The Lancet in 2019 by van Hoogenhuijze et al., randomized 933 women undergoing IVF to either endometrial scratching or no scratching before their next cycle.

Results:

• Cumulative live birth rate: 38.5 percent in the scratch group vs 35.6 percent in the control group
• Difference: 2.9 percentage points (95% CI -3.2 to 9.1), not statistically significant
• No subgroup analysis (including women with prior implantation failure) showed convincing benefit

The Lensen Trial (NEJM 2019)

The same year, Lensen et al. published a larger trial in NEJM, randomizing 1,364 women across multiple centers in Australia, the UK, and the Netherlands.

Results:

• Live birth rate: 26.1 percent in the scratch group vs 26.1 percent in the control group
• Identical outcomes — no benefit detected, even in women with prior implantation failure

These two large, well-designed trials largely settled the question.

The 2024 Cochrane Update

The most recent Cochrane systematic review on endometrial injury for IVF, updated in 2024, concluded:

• Little or no effect on clinical pregnancy rate or live birth rate
• Moderate-certainty evidence
• Recommendation against routine use

What ASRM and HFEA Currently Say

The ASRM Practice Committee does not recommend routine endometrial scratching. The UK Human Fertilisation and Embryology Authority (HFEA) rates endometrial scratching as a red light add-on, meaning the evidence does not support a clinical benefit.

Why the Early Studies Looked Positive

Prospective small studies in this area suffered from:

• Selection bias: motivated patients with strong prognostic factors
• Publication bias: positive results published, negative results unpublished
• Small sample sizes: chance findings
• Methodological inconsistencies: timing of the scratch, catheter type, control conditions

The large RCTs corrected for these issues and the apparent effect disappeared.

Are There Any Patients Who Might Still Benefit?

Some clinicians argue for selective use in a narrow group:

• Women with multiple prior failed transfers of euploid (chromosomally normal) embryos
• Specific clinical situations not well-represented in the major trials

The evidence for these subgroups remains thin, and most evidence-based clinicians have moved away from endometrial scratching for any indication.

What the Procedure Costs and Risks

• Cost: typically $200 to $500 out of pocket in North America when offered
• Risks: pain, infection risk, theoretical risk of disrupting an early implantation if accidentally performed in a conception cycle
• Time cost: an additional clinic visit in the cycle before transfer

How to Have This Conversation with Your Clinic

If your clinic recommends endometrial scratching, reasonable questions are:

• What is the published evidence supporting this in my specific situation?
• How does this fit with the SCRaTCH and Lensen trial findings?
• What is your clinic's experience and outcome data with the procedure?
• What does this cost out of pocket?
• Is there a published guideline that supports this for my situation?

A clinic that recommends the procedure should be able to articulate a reason that goes beyond "we have always done it."

The Broader Lesson: IVF Add-Ons

The endometrial scratching story is a useful illustration of how IVF add-ons can become standard practice on the basis of small early studies and patient demand, only to be quietly abandoned when proper RCTs are completed. Other add-ons that have followed similar trajectories include intralipid infusions, growth hormone supplementation, time-lapse imaging (where the evidence remains debated), and some immunological treatments.

The HFEA traffic light system is a useful framework for evaluating any IVF add-on: green (evidence of benefit), amber (uncertain), red (no evidence of benefit).

Confirm with your reproductive endocrinologist before agreeing to any IVF add-on. Ask which color it would receive under HFEA criteria. To compare clinics by their use of evidence-based protocols, use the Fertility Link Navigator.