Nine Flashcards
Describe intestinal atresia generally. Where can it happen? What will the patient usually present with? What will happen in more distal atresia?
Intestinal Atresia Congenital absence or closure of a normal opening or of a tubular
structure. Failure to form a lumen. Can affect the esophagus, small or large intestine. In
general, (but depending on the level of atresia) the patient may present with a history of
polyhydramnios, and obstruction. More distal atresia results in more severe obstruction
and abdominal distention, failure to pass meconium.
What is esophageal atresia usually associated with? What causes this? What do patients present with? What is the most common type?
Esophagus: Esophageal atresia
is frequently associated with
tracheoesophageal fistulas, i.e.,
a fistula that connects the
trachea and esophagus.
Esophageal atresia is due to
failure of linear division of the
foregut into respiratory
(trachea) and digestive
(esophagus) portions during the
4th and 5th week of
embryogenesis. The
tracheoesophageal septum
deviates in a posterior direction.
Patients present with history of
polyhydramnios, respiratory distress and aspiration, tachypnea, cyanosis,
pulmonary infiltrates due to aspiration, atelectasis, gastric distention, other
congenital malformations. Diagnosis is made radiographically. There are 5 types.
Type I with a blind proximal pouch and a distal anastomosis of the esophagus to
the trachea accounts for 85% of TEF, Type II with two blind pouches accounts for
8%.
Generally, describe the clinical characteristics of SI atresia. What is duodenal atresia associated with? How does the patient present? What is the treatment? How does the patient with jejunal atresia present? How does the patient with ileal atresia present?
- Clinical: Polyhydramnios, obstruction. The more distal atresia has greater obstruction. Less common than esophageal atresia.
a. Duodenal atresia: associated with Down syndrome (1/3), other anomalies (3/4), mucosal web distal to ampulla, bilious vomiting without marked distention, history of polyhydramnios, a double bubble on X-ray. Treatment is NG tube, IV, reanastomosis
b. Jejunal atresia – bilious vomiting without distention
c. Ileal atresia – bilious vomiting, distention, failure to pass meconium, calcification on X-ray in areas of necrosis or perforation, small colon.
Describe two possible pathogeneses for SI atresia and which type they’re more likely for? Describe the gross pathology of the 3 types.
Two theories
a. Failure of the lumen to canalize. (May be
true for duodenal atresia)
b. In utero mesenteric vascular accident.
(May be true for jejunal, ileal atresia)
a. Type I: 20% continuous bowel lumen
interrupted by a mucosal septum, intact
mesentery
b. Type II: 35-40%, blind proximal and
distal ends, connected by a fibrous
cord, mesentery intact.
c. Type III: 40-45%, blind proximal and distal ends; unattached
mesentery (Subset of type III (1/3) with V-shaped mesenteric defect)
What is the most common form of congenital intestinal atresia? What causes it? Which gender is it more common in? What are type of intestinal atresia is there? How common is it?
C. Colonic atresia – Rare obstruction, barium enema shows a blind ending distal colon.
D. Anal atresia “imperforate anus” 1/5,000 births, boys more than girls. Due to. abnormal development of the urorectal septum or failure of the cloacal diaphragm
to involute. The most common form of congenital intestinal atresia,
What are intestinal duplications? What is another name for them? Where do they occur? What are esophageal cysts like? What might accompany them? What is the most common intestinal duplication? How does it present/what is it like?
II. Intestinal Duplications: (Dorsal mesenteric cysts). Can affect esophagus, small or large intestine with a saccular or cystic duplication. Stomach and colon are uncommon
sites for duplication.
A. Esophageal cysts: Present as posterior mediastinal mass, may be accompanied by vertebral malformation. Round cyst, 1-3 cm in diameter, distal 1/3 of the esophagus, must see two separate muscular walls to be duplication cyst.
B. Gastric: Rare
C. Small Bowel: 50-60% of duplications involve small bowel. Clinical presentation includes abdominal pain, vomiting, palpable mass. Mass located on the mesenteric
border, usually not communicating with the normal lumen.
D. Colon: Rare
What is a Meckel’s diverticulum? What clinical symptoms does it cause? When? With who? How many pts. are symptomatic? What is the pathology of it?
Persistence of omphalomesenteric (vitelline) duct (which
connects the lumen of the GI tract to the yolk sac in the
embryo and the GI tract and the umbilicus in the fetus) present at 4 wks gestation, normally is obliterated to form a fibrous band, which is subsequently absorbed.
A. Clinical: Present in 2% of population, 2 times more common in males, may perforate, ulcerate, bleed or intussuscept. Most often symptomatic by age 2, although only 4% are symptomatic.
B. Pathology: Solitary, antimesenteric, ileal diverticulum. In the adult, 2 cm long, within 2 feet from the ileocecal valve (in an adult), includes all three layers of bowel (mucosa, submucosa and muscularis) 1⁄2 have ectopic exocrine pancreatic tissue and gastric mucosa. Peptic ulceration can occur in adjacent small intestine mucosa.
What is the inheritance pattern of pyloric stenosis? How does it present? What does physical exam reveal? How is it treated? What is the pathology?
IV. Pyloric stenosis (Congenital Hypertrophic Pyloric Stenosis)
A. Clinical: Familial, polygenic inheritance, seen in 1/300-900 births, male:female 4:1, most common in first born boys. Monozygotic twins have high rate of concordance.
Projectile nonbilious vomiting at 2-3 weeks of age. Physical exam reveals a firm oval mass in the region of the pylorus, the result of hypertrophy and hyperplasia of the pylorus, “olive”. Treat by surgical splitting of the hypertrophic muscle- myotomy.
B. Pathology: Hypertrophy and hyperplasia of circular muscle of muscularis propria of the pylorus
What is Hirschsprungs disease? What are two theories about the pathogenesis? What do they have in common? What parts of the intestines are involved?
Absence of enteric nervous system (ENS) ganglia in the submucosa and in the myenteric plexus of the distal bowel, leading to distal obstruction. First described by Harold Hirschsprung in 1887. 50 years ago the disease was uniformly fatal. Today < 5% fatality.
Theories for pathogenesis relate to inability of neural
crest derived cells to migrate, divide, survive or
differentiate:
- Failure of neuroblasts to make their
normal craniocaudal migration to the end of the
bowel. These neuroblasts migrate craniocaudally in
the developing embryo at 5-12 weeks of gestation. - Death of distal neurons possibly due to altered
microenvironment of the neurons. May be due to
defects in genes regulating migration or survival of
neuroblasts, neurogenesis and receptor tyrosine
kinase activity.
Results in aganglionic segment, always involves the rectum and extends for varying distances proximally. The aganglionic segment can’t transmit normal motile parastoltic waves and this interrupts peristalsis with resultant functional obstruction with dilatation
of the bowel proximal to the affected segment.
What are some genetic associations that some patients with Hirschsprungs disease have? What occurs in most cases? Which gene is involved in the majority of familial cases? What does it encome? What other mutations might be involved?
A. Clinical: 1/5,000, Boys>girls, (5:1), although girls tend to have more extensive aganglionic segment of bowel. Increased incidence in Down syndrome (10% of all
cases of Hirschsprung Disease have Down syndrome) , family history of Hirschsprung’s disease (4% sibling risk), 5% have serious neurologic abnormalities and 5% have other neural crest developmental abnormalities although most cases are sporadic.
C. Associated conditions
- Genitourinary tract abnormalities (megacystis, cryptochidism)
- Down syndrome, 2-15% of Down syndrome patients have Hirschsprung disease
- Other anomalies - VSD, hydrocephalus, colonic polyposis, intestinal atresia, anorectal malformations.
Heterozygous loss-of-function mutations in the receptor tyrosine kinase RET gene account for the majority of familial cases and about 15% of the sporadic cases. The RET gene may encode a receptor for a developmental regulator involved in the genesis of neuronal migration failure. Mutations also occur in other genes encoding proteins involved in enteric neurodevelopment including the RET ligand glial-derived neurotopic factor, endothelin and the endothelin receptor but together these account for less than 30% of patients.
How do people with HD present? How is the diagnosis made? What is treatment?
Presents with obstruction in newborn, proximal to the aganglionic region. Failure to pass meconium, distention, vomiting, constipation, diarrhea, perforation. Older children may present with long history of constipation. Diagnosis is by barium enema and rectal biopsy. Treatment is surgical.
Describe the pathology of HD.
B. Pathology: No enteric nervous system ganglion cells in distal colon, hyperplasia of
nerves. No peristalsis in the unganglionated segment. Usually (80%) the rectum and
sigmoid are the aganglionic segment. In
20% of cases a longer segment of bowel
is affected. In the long segment disease,
girls and boys are affected equally and if
girls have Hirschsprung Disease, it tends
to be more extensive than in boys. The
aganglionic segment has hypertrophy of
the fiber tracts arising from extrinsic
neurons in the lamina propria and
muscularis mucosa, which can be seen
with Acetyl cholinesterase staining, but
no ganglion cells. The involved segment is typically contracted and empty. The
segment proximal to the involved segment is distended by fecal accumulation and is
called “megacolon” A submucosal biopsy is accurate in about 85% of cases but in
some cases a full thickness biopsy may be necessary.
Enterocolitis or megacolon dilatation of the proximal, ganglionated bowel if not
treated. Treatment is surgical – relieve the obstruction and connect the ganglionated
bowel to the anus.
What is extrahepatic biliary atresia? What are some etiologies? How does the patient present? If untreated, what does it lead to? What are some possible treatments? What is the pathology? What can it be associated with?
Extrahepatic biliary atresia: Partial or total absence of bile ducts between the porta hepatis and the duodenum. Heterogeneous etiology. May be due to the in utero
inflammatory injury to the bile duct with subsequent scarring and loss of the lumen or abnormal bile duct differentiation.
A. Clinical: 1/20,000 live births, most common cause of persistent neonatal cholestasis. Jaundice. Infants may have acholic stools. Otherwise the baby looks good. If left untreated leads to death from cirrhotic liver failure. Kasai procedure (hepatic porto-enterostomy) before 10 weeks of age can restore bile flow but there is a high failure rate. Transplantation may be necessary.
B. Pathology: Extrahepatic bile ducts are fibrous cords. Intrahepatic ducts initially proliferate (peak at 205 d) as a response to the obstruction, then fibrose and regress
(by 400 d). If the surgeon has a bile duct at the porta hepatis of larger than 200 u in diameter, Kasai may work.
C. Associated: 20% of cases have associated anomaly. Polysplenia syndrome, situs inversus
What might patients with body wall defects have a history of?
Body wall defects: 1/3,000 live births. May have history of elevated maternal alpha-fetoprotein.
What is an omphalocele? Mortality rate? What is the pathology? Treatment? ASsociated abnormalities?
- Clinical: 1/5,000 – 1/6,000, persistence of the body stalk in the midline, due to failure of the intestine to return to the abdomen at 10-11 weeks of age, 50% mortality
- Pathology: Abdominal contents covered by a ventral sac of inner peritoneum and outer amnion. Liver, small and large intestine are in the sac. Treatment is either primary closure if the defect is small enough or a staged closure with a silo. May be due to incomplete lateral folding or incomplete migration and differentiation of the mesoderm.
- Associated abnormalities. In 40-70% - diaphragmatic hernia, cardiac, renal, trisomy 13,18, 21, Beckwith Wiedemann Syndrome, Cantrell’s Pentalogy,
malrotation.
