Gastrointestinal pathology
Terms
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- Meckel's diverticulum
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Remnant of the omphalomesenteric (vitelline) duct. Forms an ileal diverticulum (occasionally cyst or fistula).
-Most common congenital anomaly of GI tract (1-4% of infants)
-Antimesenteric border of small intestine
-Rule of 2's: 2% prevalence, 2 feet from ileocecal junction,presents in first 2 years
-Symptom: painless bleeding
-All three layers of abdominal wall
-May have ectopic gastric or pancreatic tissue
-Often asymptomatic
-Symptomatic more common in males - Pancreas divisum
- Failure of dorsal and ventral pancreatic buds to fuse
- Hirschsprung's disease
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Absence of autonomic ganglion cells in myenteric plexus of colon. Due to failure of neural crest cells to migrate at 5-7wks.
-Megacolon: proximally constricted, distally dilated
-More common in males
-Genetics: RET, endothelin receptor B, trisomy 21 - Esophageal atresia and tracheoesophageal fistula
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Cause: error in development of tracheoesphageal septum.
Most to least common:
1) proximal EA with distal TEF
2) EA
3) "H-TEF" - Omphalocoeles
- Cause: failure of intestines to return to abdominal cavity during 10th week. Surrounded by amnion.
- Esophageal stenosis
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Developmental error in recanalization of esophagus
-Most common in distal 1/3 - Duodenal atresia
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Complete occlusion of duodenal lumen
-More common in premature and Trisomy 21 infants
-2nd and 3rd parts of duodenum - Anorectal abnormality
- Abnormal development of urorectal septum (division of cloaca).
- Umbilical hernia
- Herniation of intestines through incompletely closed umbilicus (after they have returned to the abdomen).
- Annular pancreas
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Cause: fusion of dorsal and ventral pancreatic buds around the duodenum; can cause duodenal stenosis
-Can also present later in life with pancreatitis or malignancy - Duodenal stenosis
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Cause: incomplete recanalization due to defective "vacuolization"
-Stenosis from external constriction can be caused by annular pancreas
-most common in 3rd and 4th parts
-vomiting WITH bile - Volvulus
- Malroation of gut, cutting off blood supply. Can be congenital or later in life.
- Congenital pyloric stenosis
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Cause: hypertrophic, contracted pylorus
-Most common congenital anomaly of stomach
-Non-bilious projectile vomiting
-More common in males - Gastroschisis
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Defect in abdominal wall that allows abdominal viscera to escape. Next to the umbilicus, not involving it, usually on the right. Due to incomplete closure of lateral folds during 4th week gestation.
-more common in males