For many families in the UK a callosal abnormality is picked up on routine ultrasound scanning during pregnancy at around 20 weeks. It can be difficult to know how to handle such an unexpected result like this and it is important to get as much information as you feel is necessary to make decisions about your family’s future. Your obstetrician will be able to give you more information about what the scan shows. In some cases they may suggest having a MRI scan during the pregnancy to look at the baby’s brain in more detail.
The corpus callosum is most reliably seen on ultrasound scan from 20 weeks of pregnancy onwards. At this point the brain has not fully developed and it can be very difficult to assess whether there are any changes in the corpus callosum or other brain structures. As the pregnancy progresses the brain develops further and more detail can be seen. A MRI scan may be useful in some circumstances but how much information this, or an ultrasound, can provide will depend on at what stage of pregnancy it is performed.
For a small number of families in whom a diagnosis has been made in an affected individual with a genetic test there may be the option of having a test during a pregnancy to see if the foetus is affected. If this is the case then it is useful to discuss the issues surrounding prenatal testing and its risks if possible before embarking on a pregnancy. For many families diagnosis in pregnancy relies on ultrasound and/or MRI scanning. In either case your local obstetrician or clinical genetics department will be able to discuss this with you in more detail.