USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 26-year-old, gravida 2, para 1, comes to the emergency department in active labor. She has not received prenatal care during this pregnancy. A 3500-g (7.7-lb) boy is delivered via uncomplicated vaginal delivery. However, the newborn shows an abdominal wall defect immediately to the right of the umbilicus with exposed, red, thickened, and foreshortened bowel protruding from the defect. Which of the following is the most likely cause of this birth defect?
Content Reviewers:Rishi Desai, MD, MPH
Contributors:Tanner Marshall, MS
With gastroschisis, gastro- refers to the gastrointestinal tract, and -schisis refers to separation; so in gastroschisis, the anterior abdominal wall fails to close and remains open or separated throughout fetal development, and this results in a newborn’s abdominal organs, often the intestines, protruding out and being exposed to the outside environment.
Looking at the embryo in the horizontal plane, the two lateral folds eventually come together and close off at the midline, except for one tiny spot where the umbilical cord connects the fetus to the placenta.
That opening later becomes the umbilicus, also known as the belly button.
This folding allows for the formation of the gut within the abdominal cavity.
With gastroschisis, those lateral folds don’t close all the way, essentially leaving an opening in the abdominal wall.
The hole almost always extends through the rectus muscle to the right of the umbilicus, although it’s not really known why it tends to be on the right side.
Whatever the reason is, this opening allows the developing organs to protrude through into the amniotic sac.
Exposing the abdominal organs to amniotic fluid can sometimes cause the intestines to get irritated and inflamed, which can lead to malabsorption issues.
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