1
Q
describe tracheoesphageal fistula
A
- TEF is an abnormal passage between the trachea and the esophagus
- incomplete fusion of the tracheoesophageal folds results in a defective tracheoesophageal septum and communication between the trachea and esophagus
- polyhydramnios is often associated with esophageal atresia and TEF
2
Q
describe esophageal atresia
A
- esophageal atresia is frequently associated with TEF and results from deviation of the tracheoesphageal septum in a posterior direction, and as a result, separation of the esophagus from the laryngotracheal tube is incomplete
- in some cases, the atresia results from failure of esophageal recanalization
- a fetus with esophageal atresia is unable to swallow amniotic fluid, resulting in polyhydramnios
3
Q
describe esophageal stenosis
A
- narrowing of the lumen of the esophagus can anywhere along the esophagus, but usually occurs in the distal one third, either as a web or as a long segment of esophagus with a threadlike lumen
- the stenosis usually results from incomplete recanalization of the esophagus, but may also result from a failure of esophageal blood vessels to develop in the affected area
4
Q
describe congenital hypertrophic pyloric stenosis
A
- infants with this anomaly have marked muscular thickening of the pylorus, which results in severe stenosis of the pyloric canal and obstruction to the passage of food
- as a result, the stomach becomes markedly distended and its contents are expelled with force (projectile vomiting)
5
Q
describe duodenal stenosis
A
- partial occlusion of the duodenal lumen is usually caused by incomplete recanalization of the duodenum
- most stenoses involve the 3rd or 4th part of the duodenum, and stomach contents (usually containing bile) are often vomited
6
Q
describe duodenal atresia
A
- complete occlusion of the duodenum results from failure of reformation of the lumen
- most atresias involve the 2nd and 3rd part of the duodenum, distal to the opening of the bile duct
- in infants with duodenal atresia, vomiting begins within a few hours of birth and almost always contains bile
- polyhydramnios is also seen because DA prevents normal absorption of amniotic fluid by the intesntines
- a diagnosis of duodenal atresia is suggested by the presence of a “double bubble sign”, caused by a distended, gas-filled stomach and the proximal duodenum
7
Q
describe an anular pancreas
A
- caused by the growth of a bifid ventral pancreatic bud around the 2nd part of the duodenum
- an anular pancreas may cause obstruction of the duodenum shortly after birth, but in many cases are not diagnosed until adulthood
8
Q
describe a congenital omphalocele
A
- congenital omphalocele is a persistence of the herniation of the abdominal contents into the proximal part of the umbilical cord
- the herniated intestine is covered by peritoneal membrane (omphalo-sealed) and is midline through the umbilicus
9
Q
describe an umbilical hernia
A
- forms when the intestine herniate through an imperfectly closed umbilicus
- in umbilical hernias, the protruding mass is covered by subcutaneous tissue and skin
- the hernia protrudes during crying, straining or coughing and can easily be reduced through the fibrous ring at the umbilicus
10
Q
describe gastroschisis
A
- gastroschisis results from a defect near the median plane of the abdominal wall when the lateral folds fail to fuse
- the viscrea protrude into the amniotic cavity and are bathed by amniotic fluid–there is no peritoneal membrane covering the exposed viscera
11
Q
describe mixed rotation and volvulus
A
- this type of malrotation results from failure of the midgut loop to complete the final 90 degrees of rotation
- with mixed rotation and volvulus, the cecum lies just inferior to the pylorus of the stomach and is fixed to the posterior abdominal wall by peritoneal bands that pass over the duodenum
- these bands and the volvulus usually cause duodenal obstruction
12
Q
describe reversed rotation
A
- the midgut loop rotates in a clockwise rather than counterclockwise direction and as a result, the duodenum lies anterior to the SMA rather than posterior to it
- the transverse colon may be obstructed by pressure from the SMA
13
Q
describe midgut volvulus
A
- midgut volvulus is an anomaly in which the small intestine does not enter the abdominal cavity normally and the mesenteries do not undergo normal fixation; as a result, twisting of the intestines occur
- these vessels are usually twisted and become obstructed at or near the duodojejunal junction and the circulation to the twisted intestine is restricted
14
Q
describe an ilieal diverticulum (Meckel’s)
A
- an ileal diverticulum represents a remnant of the proximal portion of the omphaloenteric duct–it typically appears as a fingerlike pouch that arises from the ileum
- an ileal diverticulum is of clinical significance because it someimtes becomes inflamed and causes symptoms that mimic appendicitis
- if gastric mucosa is present instead, diagnosis is made by IV injection of tecnetium-99 (99Tc)
- an ileal diverticulum ay be connected to the umbilicus by a fibrous cord or an omphaloenteric fistula
15
Q
describe congenital megacolon (Hirschsprung disease)
A
- part of the colon is dilated because of the absence of autonomic ganglion cells in the myenteric plexus distal to the dilated segment of colon
- the dilation results from failure of peristalsis in the aganglionic segment, which prevents movement of the intestinal contents
16
Q
describe an imperforate anus
A
- most anorectal anomalies result from abnormal development of the urorectal septum, resulting in incomplete separation of the cloaca into urogenital and anorectal parts
17
Q
describe anal stenosis
A
- the anus is in a normal position, but the anus and the anal canal are narrow
- this is caused by a slight dorsal deviation of the urorectal setpum as it grows caudally to fuse with the cloacal membrane
BSCE Embryology
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