Congenital gastrointestinal disorders: Pathology review

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A 5-year-old girl is brought to the pediatrician for evaluation of abdominal pain and bloody stools. The symptoms began three-weeks ago. The abdominal pain is intermittent and usually self-resolves within an hour. Past medical history is noncontributory. She has been meeting all developmental milestones. Physical examination reveals a nontender and nondistended abdomen with normal bowel sounds. Laboratory testing reveals the following:
 
 Laboratory value  Result 
 Hemoglobin  15.2 g/dL 
 Platelet count  260,000/mm3 
 Prothrombin time  14 seconds 
 Partial thromboplastin time  32 seconds 
 
A radiolabeled technetium-99 scan is performed and reveals increased uptake in a structure located in the right lower abdominal quadrant. The walls of this structure will most likely consist of which of the following? 

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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.

Sources

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  4. "The risk of midgut volvulus in patients with abdominal wall defects: A multi-institutional study" Journal of Pediatric Surgery (2017)
  5. "Special basic science review" Journal of Pediatric Surgery (2000)
  6. "Management of paediatric hernia" BMJ (2017)
  7. "Diagnosis of Inguinal Region Hernias with Axial CT: The Lateral Crescent Sign and Other Key Findings" RadioGraphics (2011)
  8. "Imaging Manifestations of Meckel's Diverticulum" American Journal of Roentgenology (2007)
  9. "Management of asymptomatic or incidental Meckel’s diverticulum" Indian Pediatrics (2009)
  10. "Prenatal Risk Factors and Outcomes in Gastroschisis: A Meta-Analysis" PEDIATRICS (2015)
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