Shannon M. Clark, MD, FACOG on Instagram: "#stitch with @dr.z_neurosurgery From UpToDate: Most cases of ABS are sporadic. The etiology is heterogeneous and controversial. In most cases, loose strands of amnion adhere to and then entangle the embryo/fetus or germ disc, resulting in mechanical or vascular disruption of developing structures. However, in some cases, amniotic bands may not be involved, and the primary etiology may be vascular disruption or a pathogenic variant in a developmental gen