Egg collection day: what happens, from trigger to the first phone call

Egg collection (also called oocyte pick-up, OPU, or egg retrieval) is the hinge of the cycle: the day the work moves from your body to the laboratory. Here is the whole day, including the part behind the hatch.

Before: the trigger

When your follicles reach size, you take a "trigger" injection at a precise time — often late evening. Egg collection is scheduled 34–36 hours later. Being on time to the minute matters more than for any other injection in the cycle.

The procedure

You'll be sedated. The doctor passes a thin needle, guided by ultrasound, through the top of the vagina into each follicle and draws out the fluid. Each tube of fluid is passed straight into the adjoining lab. It takes 15–30 minutes. Recovery is an hour or two; someone should take you home.

In the lab, in the first hour

An embryologist tips each tube into a dish on a warm stage and searches under a microscope. An egg surrounded by its cloud of cumulus cells looks like a small hazy dot to the naked eye. Each one found is rinsed and moved to a labelled dish in an incubator. The count they give the doctor — "we have nine" — is the number of egg-cumulus complexes found, not yet the number of mature eggs.

Meanwhile, the sperm sample is being prepared in another part of the lab.

Two to four hours later: how many are mature?

For ICSI, the cumulus cells are stripped away with an enzyme and gentle pipetting so the egg can be seen clearly. Only now can the embryologist tell which eggs are mature (MII — with a small "polar body" visible), which are nearly there (MI), and which are immature (GV). Typically 70–85% are mature; only mature eggs can be injected. For conventional IVF the eggs aren't stripped, so maturity is estimated rather than counted precisely.

Injection (ICSI) or insemination happens a few hours after collection, so that afternoon or evening.

The first phone call

Most clinics phone the same day or the next morning with: eggs collected, how many were mature, and how many were injected or inseminated. The next call — the following morning — is fertilisation. Why the numbers go down at every step →

What "no eggs" or "far fewer than expected" can mean

Rare, and always investigated: trigger taken late or missed, follicles that were empty or already ovulated, or occasionally an issue with the trigger drug itself. It is a devastating call to receive, and a good clinic will sit down with you and go through exactly what happened.