Chapter 3 • Abdomen, Pelvis, and Perineum
Extrahepatic BiliaryAtresia
Occurs when the lumen ofthe biliary ducts is occluded owing to incomplete re canalization.This condition is associated with jaundice, white-colored stool, and dark-colored urine.
Annular Pancreas
Occurs when the ventral and dorsal pancreatic buds form a ring around the duo denum, thereby causing an obstruction ofthe duodenum and polyhydrarnnios
DuodenalAtresia
Occurs when the lumen ofthe duodenum is occluded owing to failed recanaliza tion. This condition is associated with polyhydramnios, bile-containing vomitus, and a distended stomach.
Omphalocele
An omphalocele occurs when the midgut loop fails to return to the abdominal cavity and remains in the umbilical stalk.
•The viscera herniate through the umbilical ring and are contained in a shinysac of amnion at the base of the umbilical cord.
•Omphalocele is often associated with multiple anomalies of the heart and nervous system with a high mortality rate (25%).
Gastroschisis
Gastroschisis occurs when the abdominal viscera herniate through the body wall directly into the amniotic cavity, usually to the right of the umbilicus.
•This is a defect in the closure of the lateral body folds and a weakness of the anterior wall at the site of absorption of the right umbilical vein.
•Note that the viscera do not protrude through the umbilical ring and are not enclosed in a sac of amnion.
lleal (Meckel) Diverticulum
Occurs when a remnant of the vitelline duct persists, thereby forming a blind pouch on the antimesenteric border of the ileum. This condition is often asymp tomatic but occasionally becomes inflamed ifit contains ectopic gastric, pancre atic, or endometrial tissue, which may produce ulceration. They are found 2 feet from the ileocecal junction, are 2 inches long, and appear in 2% ofthe population.
Vitelline Fistula
Occurs when the vitelline duct persists, thereby forming a direct connection be tween the intestinal lumen and the outside ofthebodyatthe umbilicus. This condi tion is associated with drainage ofmeconium from the umbilicus.