Hernia Vs. Vascular Malformation

My son is 7 months old. I took him to the doctors for what I thought was a hernia, although this hernia was above his naval and it is blueish, like a bruise. The doctor's diagnosis was ventral hernia vs. A vascular malformation. It looks like a hernia and is not always visible, but it is blueish like a bruise. My son does have problems with constipation.
Can a hernia be blueish?
Has anyone heard of this? It is 1.5cm in size.

He does have an appointment with a pediatric surgeon although it is not for 6 weeks.

Any advice for a worried mother?
:?: