At a twin ultrasound 5 weeks scan you may have a hunch that you are pregnant with twins. Maybe you know that your chances are higher due to your family history or use of fertility treatment. In either case you’re probably curious to know how early you can detect twins. It depends on the chorionicity of your twins. Chorionicity relates to the number of placentas and has to do with whether your twins are monochorionic or dichorionic twins.
- Dichorionic twins have their own placentas. They don’t share the inner sac (amnion) or the outer sac (chorion). They can be fraternal or identical.
- Monochorionic twins share a placenta. They share the outer sac (chorion) and in very rare cases the inner sac as well (amnion). They are always identical.
Twin ultrasound 5 weeks – What can you detect?
If you get a vaginal scan at 5 weeks, the sonographer should be able to able to detect two separate gestational sacs if you’re expecting dichorionic twins. Monochorionic twins are detected by heart beat after 6 full weeks have passed. That’s when you’re 6+0 weeks pregnant. This means that all twins can be detected after week 6+0, regardless of what type of twin they are. You can’t be sure that your twin pregnancy is progressing as it should, before you’ve detected their hearts and seen them beat.