Limb-body wall defect. Is there a defensible hypothesis and can it explain all the associated anomalies?

Aside from gastroschisis and omphalocele, major defects of the ventral body (thoracoabdominal) wall are relatively uncommon and almost universally lethal. They are most often associated with other anomalies including those of the limbs that may range from amelia to mild positional deformations, unusual craniofacial malformations, and a variety of visceral abnormalities that include the heart, lungs, genitourinary system, and gut. This complex of ventral wall anomalies has been discussed under a broad and changing nomenclature that has included amniotic band disruption complex, amnion rupture sequence, limb-body wall defect (or complex), and simply body wall complex. Three major theories have been suggested to explain this complex: early amnion rupture (operating through uterine pressure and/or disruption by amniotic bands), vascular compromise (primarily hypoperfusion), and an early intrinsic defect of the developing embryo. We present four patients that illustrate the spectrum of ventral body wall defects, and from there critique the current hypotheses of pathogenesis. We conclude that this association of malformations originates as early as the embryonic disc stage, and that some of the observed associated anomalies are secondary complications of the primary disturbance in embryogenesis. We propose a new explanation for the atypical facial clefts and cranial malformations that are often observed.