Evaluation of the fetal skeleton is part of the first trimester ultrasound exam conducted around week 12 of pregnancy. Many skeletal dysplasias, especially the lethal ones, may be diagnosed or suspected at the first ultrasound exam, but a follow up ultrasound may be necessary to evaluate whether the fetal bones are growing.  The routine 20 week anatomy ultrasound is another time the fetal skeleton is evaluated, and many of the less severe (non-lethal) dysplasias may be suspected or diagnosed at this time.  However, many skeletal dysplasias, including achondroplasia, may not become evident until later in the pregnancy.

Because there are literally hundreds of variations of skeletal dysplasia, a precise diagnosis can be made only about 65 percent of the time during pregnancy.  However, our team of Maternal-Fetal Medicine Specialists are highly experienced and usually able to diagnose the lethal skeletal dyplasias during the first half of pregnancy.  In less severe skeletal dysplasias, a more accurate diagnosis about which type of dysplasia it is may be determined after birth when our team of specialists can examine the baby’s appearance, growth pattern, X-rays, and genetic testing.

If skeletal dysplasia is suspected during pregnancy, the mother may have a more detailed ultrasound exams, which can show abnormalities such as missing or fractured bones and short limbs.  You will also meet with one of our Genetic Counselors and Maternal-Fetal Medicine physicians.  In some cases, the physician may suggest a magnetic resonance imaging (MRI) study using techniques calibrated for fetus safety. Other tests intended to identify genetic markers associated with skeletal dysplasia may be suggested, including parental testing, chorionic villus sampling or amniocentesis.