that can be rigid or non-rigid and made of natural biomaterials such as a bovine pericardium or artificial materials. the skin is then closed over the patch and it is re-vascularised by the body's liver blood vessels post-surgery. the staged surgery is required, as rushed reduction of the exomphalos compromises venous return and ventilation, as it raises intra-abdominal pressure. in some cases, stretching of the abdominal wall to accommodate intestinal contents may be required. non-operative therapy uses escharotic ointments. this is used for infants with large omphaloceles that have been born prematurely with respiratory insufficiency and associated chromosomal defects, as they would not be able to tolerate surgery. the ointment causes the sac to granulate and epithelialize, which leaves a residual large ventral hernia, which can be repaired later with surgery when the baby is more stable. after surgery, for larger omphaloceles, mechanical ventilation and parenteral nutrition is needed to manage the baby. society and culture awareness day international omphalocele awareness day is celebrated annually in the us on january 31, as part of birth defect awareness month. several u.s. states have passed resolutions to officially recognize the date.