It seemed appropriate to use the talents of Dr. Garel and colleagues, pediatric radiologists who perform" a large number of obstretrical sonographic studies at Hopital Sainte Justine in Montreal.The following invited presentation is a clear and pragmatic discussion of a large series in one Institution and hopefully it will be followed later by similar results of pre-natal bone dysptasia sonographic studies, gastrointestinal and genitourinary diagnoses as well.