Congenital gastrointestinal disorders: Pathology review

A newborn infant boy from Syria, named Ahmad, gets transferred to the neonatal intensive care unit due to an opening in the abdominal wall. On examination, there’s a sac protruding from the center of the abdomen, with visible bowel loops. He was born to a 28 year old mother, who received no prenatal care.

Next, a 5 week old Caucasian boy named Nathaniel is brought to the clinic with bouts of projectile vomiting after every meal. On examination, an olive- shaped mass is palpated in the right upper abdominal quadrant. The baby also has sunken eyes and frontal fontanelle, and poor skin turgor.

Both children have congenital gastrointestinal disorders. Normally, during the fourth week of fetal development, the embryo starts to change from a flat, three-layer disc to something more shaped like a cylinder, a process called embryonic folding. In the horizontal plane, the two lateral folds eventually come together and close off at the midline, except for at the umbilicus, where the umbilical cord connects the fetus to the placenta. This folding allows for the formation of the gut within the abdominal cavity. If those lateral folds don’t close all the way, an opening is left in the abdominal wall, and that’s called gastroschisis, where gastro- refers to the gastrointestinal tract, and -schisis refers to separation.

For your exams, a good hint is that this opening is almost always to the right of the umbilicus, although it’s not really known why. This defect allows the bowel, and sometimes other abdominal organs, like the liver and the gallbladder, to protrude out where they are freely exposed to the outside environment. The result is that these organs become irritated and inflamed.

There is a related condition called an omphalocele, where omphalo- refers to the umbilicus, and -cele refers to hernia or swelling. Normally, during around the sixth week of development, the liver and the intestines grow really quickly, and because the abdominal cavity is still pretty small, there’s limited space, which causes them to herniate through the umbilical ring into the umbilical cord.