When there is nothing more to add

On the discomfort of not knowing.

Tomorrow, I may have to tell a patient that her embryo transfer has failed again.

It was a euploid embryo. We had looked carefully for anything we could reasonably optimise before the transfer. Everything appeared to be in place. And yet, it seems that she is not pregnant.

I know one of the questions that may come tomorrow.

Why didn't it work?

And the most honest answer may be: I don't know.

That is a difficult answer for a patient to hear. It is also a surprisingly difficult answer for a doctor to give.

Reproductive medicine gives us an extraordinary sense of precision. We precisely measure follicles, monitor hormone concentrations, grade blastocysts and can test embryos for chromosomal abnormalities. We calculate the timing of progesterone and embryo transfer down to hours.

With so much information available to us, it is easy to feel that we should be able to explain every outcome. But we cannot. Sometimes, despite everything appearing favourable, pregnancy simply does not happen. And this is where another difficulty begins. When treatment fails, both patient and doctor desperately want the next attempt to be different.

We want to find something we missed. Another test. Another explanation. Another medication. Something we can change before trying again. Doing something feels better than doing nothing.

For the patient, it can restore a sense of control: next time we will do this differently.

For the doctor, perhaps it does something similar. It is uncomfortable to sit opposite someone who is devastated and say that we do not yet understand why this happened — and that we may not have anything meaningful to add.

I wonder whether this discomfort is part of what has allowed so many fertility treatment add-ons to flourish. I think every intervention should still have a reason. We should be able to ask what evidence supports it, whether it has a realistic possibility of improving the outcome, and what risks or burdens it introduces.

The absence of an explanation is not, by itself, evidence that we need another treatment. And that can be an extraordinarily difficult thing to accept when another precious embryo is involved.

Saying “I don't know” can feel like admitting defeat. I’m trying to think the opposite. Sometimes it means acknowledging the limits of what reproductive medicine can currently explain. And sometimes it means sitting with a patient in a painful moment without immediately trying to make that moment easier by offering another test, another drug or another protocol.

Tomorrow, if the blood test confirms what today's pregnancy test suggests, I will have to have that conversation. I wish I could give her an explanation. I wish I could tell her exactly what we should change next time. Perhaps, after reviewing everything again, I will find something worth changing. But perhaps I won't.

And if I don't, my responsibility is not to invent an answer simply because both of us desperately want one. Sometimes the most honest medicine begins with acknowledging what we do not yet know.