Endometrial Scratch: Why This Popular Add-On Fell Out of Favor

Endometrial scratch (also called endometrial injury or endometrial biopsy in the IVF context) was one of the biggest IVF add-on trends of the 2010s. The pitch: a small deliberate injury to the endometrium in the cycle before transfer, done as an office procedure with a thin catheter, would stimulate a healing response that would somehow improve implantation in the next cycle.

Early observational studies and small trials showed dramatic apparent improvements in pregnancy rates — sometimes 20–30% absolute increases. The procedure was cheap, quick, and low-risk. Clinics adopted it widely. Patients requested it by name.

Then better trials happened.

The Big Trial That Changed Things

The PIP trial (Pipelle for Pregnancy) was a 1,364-patient multi-center randomized controlled trial published in the New England Journal of Medicine in 2019. It compared endometrial biopsy versus no biopsy in the cycle before frozen embryo transfer.

Result: no significant difference in live birth rates. The scratch group and the no-scratch group had essentially identical outcomes.

Subsequent Cochrane reviews (updated periodically) have found that when studies of higher methodological quality are analyzed together, endometrial scratch shows little to no benefit for live birth rate in most patient groups.

Why Did Early Studies Show Benefit?

The pattern is familiar in medical research: small studies with less rigorous controls often show effects that disappear in larger, better- designed trials. Several factors likely contributed to the early positive results:

• Selection bias: patients enrolled in early observational studies weren't randomly assigned
• Publication bias: positive results got published; null results often didn't
• Small sample sizes: random variation looked like real effects
• Regression to the mean: patients recruited after prior implantation failure were regressing toward their baseline pregnancy probability regardless

Where Scratch Might Still Have a Role

A small subset of the evidence suggests possible benefit in specific subgroups, though even here the picture is uneven:

Recurrent implantation failure (RIF)

Patients with 2+ failed prior IVF transfers of good-quality embryos. Some meta-analyses show modest benefit in this group. But the definition of RIF is inconsistent across studies, and the effect size is smaller than early studies suggested.

Poor endometrial receptivity by imaging

Some evidence suggests possible role when hysteroscopy or ultrasound suggests endometrial issues that scratch might address. This is speculative and not well-supported.

What Modern Guidelines Say

Major fertility societies (ASRM, ESHRE, HFEA) have updated their positions. Rough summary:

• ASRM: does not recommend routine endometrial injury for improving IVF outcomes
• ESHRE: notes lack of consistent evidence; not recommended routinely
• HFEA (UK): amber-yellow rating in add-on traffic light system — "limited evidence"

Some individual reproductive endocrinologists still offer it for recurrent implantation failure. That's a defensible clinical judgment, not a broken practice. But the routine offering that was standard in 2015 is no longer supported.

The Consumer Perspective

If your clinic offers endometrial scratch as a paid add-on for a standard IVF cycle with no history of prior failure, that's worth questioning. Reasonable questions to ask:

1. "What large trials support this in my patient population?"
2. "What's the expected effect size?"
3. "Given the current evidence, why are you recommending it for me specifically?"

A clinic that dodges these questions or falls back on "we've had good results" is falling short of modern evidence-based practice.

Cost Framing

Endometrial scratch typically runs US$300–$800 in the US and US$80–$250 in Colombia. Even at the low end, it's a real cost that should be justified by real expected benefit.