Development Of The Gut 3 Flashcards
Where do the bile duct + pancreatic duct enter the duodenum?
Midpoint of D2
Outline the rotation of the midgut
- cranial portion > small intestines
- caudal portion > large intestine
- 3 x 90° rotation results in SI on left + LI on right
- caecum descends
Outline the physiological herniation of the midgut
- the midgut grows faster than the abdominal cavity so in week 6 the intestinal loop herniates into the umbilical cord
- this forms a loop with the superior mesenteric artery which undergoes 3 x 90° rotations
- in week 10 the loop returns to the abdominal cavity
What rotational developmental problems can occur in the midgut?
- one 90° rotation: left sided colon
- reversed one 90° rotation: normal LR layout but transverse colon is behind SI
- small intestine is R/L
- large intestine is R/L
- transverse colon is superior or inferior
- small intestine: left
- large intestine: right
- transverse colon: superior
What is an omphalocoele?
The persistence of the physiological herniation of midgut
What is gastroschisis?
Failure of closure of the abdominal wall following folding of the embryo > gut tube + derivates outside the body cavity
What is the difference between omphalocoele and gastroschisis?
- omphalocoele: midgut structure have peritoneal covering > NOT EXPOSED to amniotic fluid
- gastroschisis: failure of abdominal wall to form properly > midgut structure NOT COVERED in peritoneum > exposed to amniotic fluid > negatively affects gut development
- Lower mortality in gastroschisis
Why is gastroschisis surgery complicated?
The abdominal cavity may not be big enough to fit the herniated structures
When does the vitelline duct regress?
Week 7
What are three vitelline duct abnormalities?
- vitelline cyst
- vitelline fistula
- Meckel’s diverticulum
What is the rule of twos for Meckel’s diverticulum?
- 2% of population
- located 2 feet proximal to ileo-caecal valve
- detected in under twos
- 2:1 ratio M:F
What is recanalisation failure?
Partial or unsuccessful of recanalisation
Partial > stenosis
Unsuccessful > atresia
What is pyloric stenosis?
Hypertrophy of pyloric sphincter
NOT recanalisation failure
What does pyloric stenosis cause in infants?
Projectile vomiting
