More than 90% of birthmarks are diagnosed by a careful medical history and physical exam.¹ Sometimes a health professional will monitor changes in a birthmark by taking photos of the birthmark over a period of time. All birthmarks need to be checked by a health professional.

If a health professional suspects that your child has other problems, he or she may do a blood test or do other tests to check your child's internal organs (liver, lungs, stomach, or intestines). Additional tests might include MRI or ultrasound. In rare cases, a health professional cuts out a piece of the birthmark (biopsy) to make a diagnosis.