4. Atresia, Fistulae, and Duplications
• Atresia, fistulae, and duplications may occur in any
part of the GI tract.
• Esophageal Atresia: cause regurgitation during
feeding. These must be corrected promptly, since
they are incompatible with life.
• A thin, noncanalized cord replaces a segment of
esophagus, causing a mechanical obstruction.
Proximal and distal blind pouches connect to the
pharynx and stomach, respectively.
•
5. Atresia occurs most commonly at or near the
tracheal bifurcation and is usually associated with
a fistula connecting the upper or lower esophageal
pouches to a bronchus or the trachea.
Fistulae can lead to aspiration, suffocation,
pneumonia, and severe fluid and electrolyte
imbalances.
Esophageal atresia is associated with congenital
heart defects, genitourinary malformations, and
neurologic disease.
6. .
Intestinal atresia is less common than esophageal
atresia but frequently involves the duodenum
and is characterized by a segment of bowel lacking
a lumen.
Imperforate anus, the most common form of
congenital intestinal atresia, is due to a failure of
the cloacal diaphragm to involute.
7. Esophageal atresia and tracheoesophageal fistula. A, Blind upper and
lower esophageal segments. B, Blind upper segment with fistula
between lower segment and trachea. C, Fistula between patent
esophagus and trachea. Type B is the most common.
8. Stenosis
Stenosis is an incomplete form of atresia in which
the lumen is markedly reduced in caliber as a
result of fibrous thickening of the wall, resulting in
partial or complete obstruction.
Stenosis may involve any part of the GI tract,
although the esophagus and small intestine are
affected most often.
Stenosis can also be caused by inflammatory
scarring, as may occur with chronic
gastroesophageal reflux, irradiation, scleroderma,
or caustic injury.
9. Congenital duplication cysts
Are saccular or elongated cystic
masses that contain redundant
smooth muscle layers. These
may be present in the
esophagus, small intestine, or
colon.
10. Diaphragmatic Hernia
Diaphragmatic hernia occurs when incomplete
formation of the diaphragm allows the abdominal
viscera to herniate into the thoracic cavity.
When severe, the space-filling effect of the displaced
viscera can cause pulmonary hypoplasia
that is incompatible with life after birth.
11. Omphalocele
• An omphalocele is a birth defect in which
• the infant's intestine or other
abdominal organs stick out of the
belly button (navel). In babies with an
omphalocele, the intestines are covered only by a
thin layer of tissue and can be easily seen.
• An omphalocele is a type of hernia. Hernia means
"rupture.
12.
13. Gastroschisis Gastroschisis represents a
congenital defect characterized by a defect
in the anterior abdominal wall through
which the abdominal contents freely
protrude.
Gastroschisis is similar to omphalocele except that it
involves all of the layers of
the abdominal wall, from the
peritoneum to the skin.
14.
15. Ectopia
•
Ectopic tissues (developmental rests)
are common in the GI tract. The most frequent site
of ectopic gastric mucosa is the upper
third of the esophagus, where it is referred to as
an inlet patch. While generally asymptomatic, acid
released by gastric mucosa within the esophagus
can result in dysphagia, esophagitis, Barrett
esophagus, or, rarely, adenocarcinoma.
16. •Ectopic pancreatic tissue
occurs less frequently and can be found in the
esophagus or stomach. Like inlet patches, these
nodules are most often asymptomatic but can
produce damage and local inflammation.
• When ectopic pancreatic tissue is present in the
pylorus, inflammation and scarring may lead to
obstruction. Because the restsmay be
present within any layer of the gastric wall, they
can mimic invasive cancer.
17. Gastric heterotopia
• Gastric heterotopia, small patches of ectopic
gastric mucosa in the small bowel or colon,
may present with occult blood loss due to
peptic ulceration of adjacent mucosa.
18. Meckel Diverticulum
• A true diverticulum is a blind outpouching
of the alimentary tract that is lined by
mucosa, communicates with the lumen, and
includes all three layers of the bowel wall.
• The most common type is the Meckel
diverticulum, which occurs in the
ileum.
19. • The Meckel diverticulum occurs as a result of
failed involution of the vitelline
duct, which connects the lumen of the
developing gut to the yolk sac. This solitary
diverticulum is a small pouch extending from the
antimesenteric side of the bowel. It is a true
diverticulum with a wall that includes mucosa,
submucosa, and muscularis propria.
20. “rule of 2s”
• Meckel diverticulae occur in approximately 2% of
the population,
• are generally present within 2 feet (85 cm) of the
ileocecal valve,
• are approximately 2 inches (5 cm) long,
• are twice as common in males as in females,
• and are most often symptomatic by age 2
(although only 4% of Meckel diverticulae are∼
symptomatic).
21. • The mucosal lining of Meckel diverticulae
may resemble that of normal small intestine,
but ectopic pancreatic or gastric tissue may
also be present.
• The latter may result in peptic ulceration of
adjacent small intestinal mucosa and present
with occult bleeding or abdominal pain
resembling acute appendicitis or intestinal
obstruction.
23. • Less commonly, congenital diverticulae occur in
other parts of the small intestine and ascending
colon.
• Virtually all other diverticulae are acquired and
either lack muscularis entirely or have an
attenuated muscularis propria.
• Although acquired diverticulae may occur in the
esophagus, stomach, and duodenum, the most
common site is the sigmoid colon.
24. Pyloric Stenosis
• more common in males
• Monozygotic twins have a high rate of
concordance,
• Family studies suggest a complex polygenic
inheritance.
• Turner syndrome and trisomy 18 are also
associated with the disease. Congenital
hypertrophic pyloric stenosis generally presents in
the second or third week of life as new-onset
regurgitation and persistent, projectile, nonbilious
vomiting.
25. • Physical examination reveals hyperperistalsis and
a firm, ovoid abdominal mass. Edema and
inflammatory changes in the mucosa and
submucosa may aggravate the narrowing. Surgical
splitting of the muscularis (myotomy) is curative.
• Acquired pyloric stenosis occurs in adults as a
consequence of antral gastritis or peptic ulcers
close to the pylorus.
• Carcinomas of the distal stomach and pancreas
may also narrow the pyloric channel due to
fibrosis or malignant infiltration.
26. Hirschsprung Disease
Congenital Megacolon
• Hirschsprung disease occurs in approximately
1 of 5000 live births. It may be isolated or
occur in combination with other
developmental abnormalities; 10% of all
cases occur in children with Down syndrome
and serious neurologic abnormalities are
present in another 5%.
27. Pathogenesis.
• Hirschsprung disease, also known as congenital
aganglionic megacolon, results when the normal
migration of neural crest cells from cecum to
rectum is arrested prematurely or when the
ganglion cells undergo premature death. This
produces a distal intestinal segment that lacks
both the Meissner submucosal and the Auerbach
myenteric plexus (“aganglionosis”). Coordinated
peristaltic contractions are absent and functional
obstruction occurs, resulting in dilation proximal
to the affected segment.
28. • The mechanisms underlying defective neural crest
cell migration in Hirschsprung disease are
unknown, but a genetic component is present in
nearly all cases and 4% of patients' siblings are
affected. However, simple Mendelian inheritance
is not involved in most cases. Heterozygous loss-
of-function mutations in the receptor tyrosine
kinase RET account for the majority of
familial cases and approximately 15% of sporadic
cases.
29. MorphologyDiagnosis of Hirschsprung disease requires
documenting the absence of ganglion cells
within the affected segment. Because migration of
neural crest cells in the Meissner and Auerbach
plexi are linked, it is possible to establish the
diagnosis preoperatively by examining suction
biopsy specimens. In addition to their
characteristic morphology in hematoxylin and
eosin (H&E)-stained sections, ganglion cells can be
identified using immunohistochemical stains for
acetylcholinesterase.
30. • The rectum is always affected, but the
length of the additional involved segments
varies widely. Most cases are limited to the
rectum and sigmoid colon, but severe cases
can involve the entire colon. The aganglionic
region may have a grossly normal or
contracted appearance, while the normally
innervated proximal colon may undergo
progressive dilation.
31. • With time the proximal colon may become
massively distended (megacolon), reaching
diameters of as much as 20 cm. Dilation
may stretch and thin the colonic wall to the
point of rupture, which occurs most
frequently near the cecum. Mucosal
inflammation or shallow ulcers may also be
present.
32. • These changes proximal to the diseased
segment can make gross identification of the
extent of aganglionosis difficult. Hence,
intraoperative frozen-section analysis of
transmural sections is commonly used to
confirm the presence of ganglion cells at the
anastamotic margin.
33. Hirschsprung disease. A, Preoperative barium enema study showing
constricted rectum (bottom of the image) and dilated sigmoid colon. B, Corresponding
intraoperative photograph showing constricted rectum and dilation of the sigmoid colon.
34. Clinical Features
• a failure to pass meconium in the immediate
postnatal period. Obstructive constipation follows,
• The major threats to life are enterocolitis, fluid
and electrolyte disturbances, perforation, and
peritonitis.
• The primary mode of treatment is surgical
resection of the aganglionic segment and
anastamosis of the normal colon to the rectum.
• .
35. Acquired megacolon
Acquired megacolon may occur at any age as a result
of
• Chagas disease,
• obstruction by a neoplasm or inflammatory
stricture,
• Toxic megacolon complicating ulcerative colitis,
visceral myopathy,
• or in association with functional psychosomatic
disorders.
Of these, only Chagas disease is associated with loss
of ganglia
