Umbilical Problems
Beginning in the fourth week of fetal life the front of the abdomen develops by tissue folding in from the sides, top and bottom. Between 6 and 10 weeks’ gestation, some of the fetus’ intestine is located outside of the main body cavity but it returns to the developing abdomen by the 10th week. By 12 weeks’ gestation, the large abdominal wall muscles in the front, called the rectus muscles, join each other in the midline except at the site of the umbilical ring (belly button), where the muscles are separated by tissue.
Figure 1. Development of umbilical cord: A) Vitelline duct connects the intestine to the yolk sac which provides nutrition to the fetus and the umbilical blood vessels (arteries and vein) develop. B) The vitelline duct and umbilical blood vessels join to form the umbilical cord. C) The allcentois leter called the urachus, connects to the top part of the bladder. Development of the abdominal wall narrows the belly button (umbilicus). |
By the time of birth, the umbilicus has been closed by the developing abdominal muscles and skin except for the space occupied by the umbilical cord which contains the umbilical vein, the two umbilical arteries, and the remaining attachments to the bladder and the intestine. After the cord is cut at birth, the blood vessels clot and the remainder of the umbilical cord dries up and eventually falls off. The resulting wound heals and becomes covered by skin which forms the umbilicus or belly button.
Drainage from the umbilicus during the early weeks of life may be from leftovers of the fetal umbilical structures or a belly button infection known as omphalitis.
Article and graphics adapted from O'Neill: Principles of Pediatric Surgery. © 2003, Elsevier.