B5-069 GI Embryology Flashcards
buccopharyngeal membrane is the site of future
mouth
cloacal membrane is the site of the future
anus
ventral mesentary forms the
hepatogastric portion of lesser omentum
dorsal mesogastrium forms the
2
greater omentum and gastrocolic liagment
only the […] has both dorsal and ventral mesentary
foregut
mid and hind only have dorsal
portion of stomach that grows much larger forming the greater curvature
original posterior portion
lienal =
splenic
dorsal mesentary forms the
greater omentum
ventral mesentary forms the
lesser omentum
the endodermal lining of the yolk sac becomes the
primitive gut
surronded by splanchnic mesoderm
2nd most common GI abnormality
infantile pyloric stenosis
male
3-10 weeks old
projectile, non-bilious vomiting
infantile pyloric stenosis
“olive” caudal to costal margin near midline
infantile pyloric stenosis
infants with pyloric stenosis may suffer from […] and […] due to loss of gastric acid
dehydration
hypochloremia
hypertrophy of pyloric spinchter muscles
plyloric stenosis
treatment for pyloric stenosis
- IV hydration
- oral atropine (relax spinchter)
- surgical intervention
suspends gut tube from posterior body wall
dorsal mesentary
forms the lower portion of septum transversum
ventral mesentary
foregut
the pancreas, 3rd and 4th portions of the duodenum become […] as gut is rotating
retroperitoneal
- evolutionarily conserved transcription factors that are used in regional patterning
- used in both mesoderm and endoderm
Hox genes
hole in back of diaphragm
Bochadlek
most congenital diaphragmatic hernias occur on which side?
left
hole in front of diaphragm near the xiphiod process
morgagni hole
- difficulty breathing
- fast breathing
- fast heart rate
- cyanosis
- abnormal chest development
- abdomen appears caved in
CHD
CHD is typically diagnosed when in pregnancy?
22-24 weeks
or in 1st trimester screening US
liver and gallbladder buds grow into the lower portion of the
septum transversum
Bockdalek hernia are […] and to […]
back and to the left
90% of CDH
breath sounds on right, bowel sounds on left side of chest
CDH
forms the falciform ligament and lesser omentum
ventral mesentary
liver growth causes the lower portion of the septum transversum to
thin
leaves falciform
part of the liver fuses with the developing diaphragm leaving
2
bare area of liver
coronary ligament
intially, dorsal and ventral […] form on opposite sides of the end of the foregut tube
pancreatic buds
ventral migrates around in 5th week
thought to arise when single ventral pancreatic bud fails to migrate and fuses to duodenum
or
when two ventral pancreatic buds form and migrate in opposite directions, constricting duodenum
annular pancreas
- polyhydramnios in utero
- difficulty feeding after birth
- non bilious vomiting
- starting day 1 for newborns
annular pancreas
- associated with maternal polyhydramnios,
- down syndrome,
- esophageal and duodenal atresia,
- imperforate anus,
- Meckel’s diverticulum
complete annular pancreas
about 1/3 of newborns with annular pancreas have
trisomy of a chromosome
21, 18 or 13
in adults, this condition is associated with:
* epigastic pain
* pancreatitis
* upper GI bleeding from peptic ulceration
* other GI issues
annular pancreas
treatment for annular pancreas
typically requires surgery
duodenal bypass
- early (<24 hours) vomiting that may contain bile
- abdomen not dilated
- maternal polyhydramnios in 50% of cases
duodenal atresia
double-bubble sign
duodenal atresia
gas in stomach and 1st part of duodenum
VACTERL association
duodenal atresia
anal atresia
duodenal atresia is associated with other congenital abnormalities […]% of the time
50%
VACTERL stands for
Vertebral defect
Anal (and duodenal) atresia
Cardiac defects
Tracheo-esophageal fistula
Renal anomalies
Limb abnormalities
annular pancreas and duodenal atresia are hard to distinguish without
imaging
why can focal obstruction of the GI tract occur in almost any small lumen?
luminal occlusion by endoderm -> recanalization
recanalization failure = obstruction
recanalization errors can cause
5
- cysts
- duplications
- septa formation
- diverticuli
- failure to reopen lumen
forms primary intestinal loop with the superior mesenteric artery on its axis
midgut
from the 6th week to 10th week, the instestines are physiologically
hernia
occuring at same time as recanalization
recanalization occurs during what weeks of development
6-9
failure of the gut to return to the peritoneal cavity
omphalocele
in an omphalocele, the intestinal loops is covered with […] which is attached to an enlarged umbilical cord
amnion
navel covered with thin layer of amnion
omphalocele
- involve herniated small intestine only
- repaired shortly after birth
- may be able to be delivered vaginally
small omphalacele
- may involve herniated liver and even spleen
- may require multiple surgeries
- typically delivered via C section
omphalocele
- detected by prenatal US
- elevated alpha-fetoprotein levels
2
omphalocele
gastroschisis
about half of babies with omphaloceles have trisomy of
chromosomes 18 or 21
25-45% of babies with omphalocele have other birth defects like
4
- heart defects
- neural tube defects
- CDH
- chromosomal abnormalities
- maternal age younger than 20 or older than 35
- alcohol/tobacco use while pregnant
- SSRIs
- obesity
risk factors for
omphalocele
failure of body wall closure followed by gut herniation
gastroschisis
- typically occurs to the right of umbilicus
- intestines not covered with membrane
gastroschisis
defect in anterior abdominal wall through rectus abdominis, just to right of umbilicus
gastroschisis
gastroshisis is more frequent in […] mothers
young, teenage
gastroschisis is inherited in an […] manner
autosomal recessive
not associated with other congenital defects
greatest risk for ischemia of gastroschisis
volvulus
congenital anomaly of gut due to remnant of vitelline duct
meckel’s diverticulum
meckel’s diverticulum is a remnant where the vitilline duct was attached to the […]
ileum
rule of 2s for Meckel’s
- 2% of population
- 2’’ long
- located 2 ft from ileocecal junction
- presents before age 2
- may contain 2 ectopic tissue (stomach/pancreas)
- abdominal pain
- blood in stool
- presents before age 2
- twice as frequent in males
Meckel’s diverticulum
pain mimics appendicitis but that doesn’t happen in two year olds
meckel’s
how is Meckel’s diagnosed?
- radioactive technetium-99 injection and pertechetate scan
- colonoscopy
caused by failure of neural crest cell to migrate around developing intestines
hirschsprung disease
failure of RET gene
hirschsprung disease
results in non-motile portion of bowel due to lack of ENS
hirschsprung disease
suspected if meconium is not passed within 48 hours of birth
hirschsprung disease
- abdominal distension
- constipation
- diagnosed prior to first birthday
hirschsprung disease
hirschsprung disease is associated with trisomy
21
often discovered when unable to obtain rectal temp
imperforate anus
why does imaging follow the discovery of anal atresia?
- to plan surgical correction
- to look for other congenital defects
typically […] VACTERL defects are present in affected individuals
3
imperforate anus is associated with trisomy
18/21
the part that prolapses into the other is called the […] and the part that receives it is called the […]
- intussusceptum
- intussuscipiens
- below age of 5
- sudden pain that comes and goes
- vomiting
- stool mixed with blood
- cramping abdominal pain
- may palpate “sausage mass”
intussusception
bull’s eye or target appearance on US
intussusception
treatment intussusception
barium or air enema
laparotomy
surgery
most common location of intussusception
ileocecal junction
adults who have their spleen removed are at a 10-20x higher risk of death due to
sepsis
most babies born without a spleen […] within the first few months of life
die
due to infection
asplenia or polysplenia are often associated with
other congenital defects
a single accessory spleen or lobulated spleen is usually
asymptomatic
