Omphalocele

Abstract

Omphalocele is the herniation of part of the intraabdominal contents through the umbilicus. As opposed to umbilical hernia, omphalocele is not covered by skin, and a translucent avascular membrane, consisting of peritoneum inside and amniotic membrane outside, covers the herniated viscera. The umbilical cord usually is inserted into the sac and the umbilical vessels run radially within its wall. The omphalocele sac varies in size from a slightly enlarged cord, containing only a single loop of intestine to a giantic sac, containing a major portion of the liver and the other solid and hollow viscera of the abdomen. There is no relation between the size of the sac and the diameter of the umbilical defect, a medium sized sac may have a broad base and a large sac may have a narrow neck which appears pedunculated. In this anomaly, the abdominal cavity is usually small, and when the sac is large, the lower part of the thorax is less flared than normal. There is no deficiency of the abdominal wall other than that of the skin over the herniation itself. The rectus muscles are intact even when the sac is gigantic and the defect extends from flank to flank and from xiphoid to half way between the umbilicus and pubis. Most, if not all, patients with omphalocele have incomplete rotation and fixation of the midgut. The intact omphalocele sac may rupture partially or completely either in utero, during labor or after birth. The sac is thin and avascular, on exposure to air dries out easily and when ruptured is a potential site for the entry of lethal bacteria. In patients with a postnatally ruptured sac, the appearance of the intestine is essentially normal. In those with prenatally or perinatally ruptured sac, however, the eviscerated mass of the intestine is hyperemic, thickened and edematous. The intestine is reltively rigid, matted together and firmly covered with a fibrinogelatinous membrane or peel with no appaent peristalsis.