Good embryos, no pregnancy: what to check before the next transfer.

Recurrent implantation failure is when good-quality embryos have been transferred often enough, without a pregnancy, that it is worth looking for a reason.

There is no single agreed number. Many clinics used to say three failed transfers of good embryos. The European society (ESHRE, 2023) now judges it for each couple, by the woman's age and the number and quality of embryos transferred. It is different from recurrent miscarriage, where pregnancies start and are then lost.

The most common reason a good-looking embryo does not implant is a chromosome error in the embryo, which cannot be seen under the microscope and becomes more common with age.

Less often the cause is in the womb: a polyp, a fibroid, scarring, or a fluid-filled tube leaking back into the cavity. Sometimes it is the cycle itself: the stimulation, the lab or the transfer. For many couples no single cause is found. That is why we review all three, not only the lining.

The tests with evidence are a detailed scan of the womb, hysteroscopy if the scan suggests a problem, a karyotype of both partners, and a review of lifestyle for both of you.

We also read the reports from each earlier cycle: how many eggs, how the embryos grew, how they were frozen and transferred. He has a semen analysis. Smoking, alcohol and weight are checked for both partners, because they affect embryo quality too. Where a scan shows a hydrosalpinx, it is treated before the next transfer.

Jananam no longer recommends the ERA test, after using it in more than 750 patients.

ERA takes a biopsy of the lining to time the transfer. It adds a cycle, a procedure and a bill. Both ESHRE and ASRM now advise against its routine use, including after repeated implantation failure. Our full reasoning is in the journal.

We use a small number of extra tests only for selected couples, and we decline routine immune treatments and receptivity tests.

Immune testing is reserved for a specific subgroup, not applied to everyone. For selected women, EMMA/ALICE testing looks for harmful bacteria in the lining. PGT-A is considered from 38, or after repeated failure. Steroids, IVIG and intralipid drips are not given routinely.

Once the review is done and anything found is corrected, there is usually no reason to wait long before the next transfer.

The next transfer is planned with a reason for every change: often a frozen transfer, one embryo where suitable, and the cavity checked first. Time matters, especially for the woman's eggs. If you have frozen embryos from before, they may be the next step.