To dream of a baby sonogram (whether it was yours or someone else’s) may be a metaphor for a new stage you are beginning in your life (such as a new relationship, job or friendship). You may feel that you are being put to the test as to whether you are prepared or ready for these changes.
If you are nervous that you might be pregnant, this dream is a literal reflection of your anxieties about getting pregnant.
If you have been less than truthful with someone in your real life, this dream could also mean you are worried they will find out about your deception.
If there was something wrong with the baby in the sonogram, you are having trouble reconciling some emotions you have been feeling, with your picture of what kind of person you are.