Can a twin pregnancy be missed at 8-weeks/12 weeks scan?
A scan at 8 weeks is unusual unless there is IVF – and then often the radiographer doesn’t tell the parent that there is a second embryo present because of vanishing twin syndrome (where early on in the pregnancy the embryo is miscarried without any symptoms and the pregnancy progresses healthily to produce one healthy baby). Until the onset of scanning, this syndrome was never picked up because by 12 weeks the incidence of it happening is vastly reduced. At the 12 week scan, particularly with current scanners becoming more and more accurate there is little chance that a second heartbeat and fetus will be missed, so unless you have consciously decided not to take that scan at all (which is quite within your rights) then there is little chance it would be missed. Do bear in mind that I am a twin who was born without detection until labour, so for hundreds of years twins were born healthily without scans.
