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Congenital anomalies are typically organized by organ system. This is an excellent organization in that similar disorders are grouped together. However, the multisystem syndromes do not fit neatly in the organ category organization. Usually the most striking finding or the most unusual finding is the one that leads to the inclusion in one or another group. Yet with the more precise information that one can now acquire it is time to organize syndromes as a separate subject.
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In the following pages we will review several syndromes that should be familiar to sonographers and sonologists either because they are fairly characteristic or common, or because their recognition will impact the management of the pregnancy. The selection of the syndromes included is somewhat artificial, but all can be detected prenatally or will affect the pregnancy.
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Clearly this review cannot be an exhaustive. The Birth Defects Encyclopedia contains about 2000 syndromes. The OMIM (Online Mendelian Inheritance in Man) was created in December 1995 as of today passed the 18,000-syndrome landmark.1 Even for physicians dedicated to the subject this is an unmanageable amount of information to grasp. Rather than attempt to read it, it is more important to learn how to investigate unusual cases. That is what we try to show here in this chapter. What are the critical findings? Compare them with some images and try to find the specific diagnosis. If you need more information, go to the Web and search the OMIM.1
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Another aspect of the prenatal diagnosis of a syndrome that must be kept in mind is the fabulous progress of molecular genetics. Since the recognition of the disorders of the fibroblast growth factor receptor (FGFR), the classification of the skeletal dysplasia (see Achondroplasia below) has been completely reorganized. These sources should be consulted because it is likely that a genetic or biochemical test can be made for these disorders that will establish the diagnosis with certainty.
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Finally, an important aspect of the prenatal diagnosis is assisting the parents in making management decisions. This is best done by providing them with contacts for support groups, and here again the Internet has revolutionized the communication between parents formerly isolated in small pockets all around the world. A good resource is NORD (National Organization for Rare Disorders), a Web site dedicated to helping people with rare diseases. In this Web site, there are more than 2000 patient organizations and other sources of help.2
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Over the last 10 years the function of the sonologist has changed significantly from simply identifying some findings to being much more proactive in the making of the differential diagnosis and the establishment of management plans. Often the sonologist will be the first one to identify the disorder, and will be the one to establish contacts with the genetics department, dysmorphology specialists, and the various cardiologists and ...