CRANIOFACIAL DAMAGE FROM AMNIOTIC BAND SYNDROME SUBSEQUENT TO PATHOLOGICAL CHORIOAMNIOTIC SEPARATION AT 10 WEEKS GESTATION

Amniotic band syndrome or amniotic disruption complex is defined as a destructive process of fetal damage in a random, nonsymmetrical distri bution, which is not attributable to aberrations in normal embryologic developmental processes. Rather, the mechanism has been considered to be initiated by rupture of the amnion, with the fetus then coming int o contact with the chorionic surface of the amniotic membrane, to whic h it adheres or becomes entwined by fibrous strands. As the fetus grow s, the tethered regions are progressively distorted, leading to constr ictions, amputations, slash defects, and body wall or cranial defects. The severity varies from a single constrictive ring of a digit to let hal thoracoabdominal evisceration or craniofacial destruction. In case s in which chorionic-amniotic separation has been diagnosed in the sec ond trimester and in which the fetal anatomic survey was initially nor mal, no instances of birth defects attributable to amniotic band syndr ome have, to our knowledge, been reported.(1) This observation has led to the theory that the rupture of the amnion must occur at a very ear ly stage of fetal development for structural defects to be produced. W e describe a case in which a sonographically normal fetus within an ab normally contracted amniotic sac at 9 weeks 6 days of gestation develo ped a huge off-axis encephalocele by the time of a scan only 3 weeks l ater.