Can Genetic Testing Be Done Before a Miscarriage Completes?

First, the miscarriage itself has to be confirmed. Under NICE guidance, if an internal scan shows an embryo of 7 mm or more with no heartbeat, or a sac of 25 mm or more with no embryo, a second opinion, a repeat scan at least 7 days later, or both, are needed; below those sizes, a repeat scan at least 7 days later, and sometimes more than one, is always needed. See no heartbeat on a scan.

A scan shortly before the sample then checks that the pregnancy is in the womb and that tissue is still there. This mirrors the research: the largest study only included pregnancies seen in the womb on ultrasound, including an empty sac, and left out pregnancies of unknown location, where an ectopic pregnancy has not been ruled out, and molar pregnancies.

The scan can also show a twin pregnancy or a vanished twin, whose DNA can confuse the result. No guideline sets an exact limit on the gap between scan and sample; the shorter it is, the more confident everyone can be that the tissue is still in place.

It should not need to. The sample is an ordinary blood draw, so you can choose waiting, tablets or a procedure for the reasons that matter to you. Tell your early pregnancy unit you are planning a test so the timing fits. If your unit advises treatment soon, for example because of a higher risk of bleeding or infection, your safety comes first.

Being asked to think about genetic testing within days of hearing that a pregnancy has ended can feel like too much. Some people want every possible answer; others want to focus on the next few days. Both are understandable, and there is no right choice.

It may help to ask what you would do with a result. For some people, learning that a chromosome change was the likely cause can ease the feeling that they did something wrong, and a chromosomal cause is linked with a better outlook in the next pregnancy than a miscarriage with normal chromosomes.

Support is available whatever you decide: Miscarriage UK's helpline is 0303 003 6464, and Tommy's midwives can be reached on 0800 0147 800.

Your NHS early pregnancy unit diagnoses and manages miscarriage free of charge and should stay at the centre of your care. In the UK, testing of pregnancy tissue is usually offered from the third miscarriage onwards and after a miscarriage from 14 weeks, or sooner when there are signs pointing to a chromosome condition. Blood-based testing is not part of standard NHS care.

Our genetic counsellors can explain, by video, whether a blood-based test might suit your situation and how it compares with tissue testing. If you are unsure about the diagnosis itself, our fetal medicine team offers a second-opinion scan in London. Because the window is short, call 020 3687 2939 as early as you can.