Which of the following congenital abnormalities are correctly defined?

B. The herniated viscera associated with omphaloceles are usually covered with a membranous sac

C. An umbilical polyp is a small excrescence of omphalomesenteric duct mucosa that is retained in the umbilicus

D. Meckel's diverticulum results when the intestinal end of the omphalomesenteric duct persists and represents a true diverticulum

DISCUSSION: Omphalocele may be seen in newborns and represents a defect in the closure of the umbilical ring. The herniated viscera are usually covered with a sac. Gastroschisis, a defect of the abdominal wall lateral to the umbilical cord, is caused by failure of closure of the body wall. The intestines protrude through the defect, and no sac is present to cover the herniated intestine. In the fetus, the omphalomesenteric duct may present as abnormalities related to the abdominal wall when the duct fails to obliterate. Meckel's diverticulum is the result of the failure of obliteration of the intestinal end of the omphalomesenteric duct. This is a true diverticulum with all layers of the intestinal wall represented. An umbilical polyp is a small excrescence of omphalomesenteric duct mucosa retained in the umbilicus. Such polyps resemble umbilical granulomas except that they do not disappear after silver nitrate cauterization. Appropriate treatment is excision of the mucosal remnant.