Congenital defects of GI tract Flashcards
How can the tracheo-oesophageal septum cause congenital defects?
By growing in an abnormal position, not normally between the trachea and oesophagus
What congenital defects are caused by abnormalities of the growth of the tracheo-oesophageal septum?
Blind ended oesophagus
Tracheo-oesophageal fistula
What is a tracheo-oesophageal fistula?
Abnormal connection between the oesophagus and the trachea
How can rotation of the midgut loop cause congenital defects?
Incompletely rotates
Rotates in the opposite direction
What congenital defect is caused by incomplete rotation of the midgut loop? Why?
Left-sided colon
because caudal limb enters abdominal cavity first
pushed to left side
What congenital defect is caused by the midgut loop rotating in the opposite direction? Why?
Transverse colon is posterior to duodenum
because the caudal limb enters the cranial limb first, without the caudal limb having rotated over the cranial limb as normal
What are the complications of congenital defects caused by abnormalities of midgut loop rotation?
Volvulus
What is volvulus?
Loop of intestine twists around itself and mesentery
giving bowel obstruction
What are the complications of volvulus?
Blood supply to bowel is cut off
gives ischaemia and necrosis of bowel
When do complications of congenital defects caused by abnormalities of midgut loop rotation present?
Most present in the neonatal period (first month after birth)
How can the vitelline duct cause congenital defects?
Doesn’t close up after physiological herniation
persists
What congenital defects are caused by a persisting vitelline duct?
Vitelline cyst
Vitelline fistula
Meckel’s diverticulum
What is a vitelline cyst?
Part of intestine contained in vitelline duct
Vitelline duct forms fibrous strands attaching the cyst to the rest of the intestines and the anterior abdominal wall
What is a vitelline fistula?
Vitelline duct remains open from intestine to umbilicus
What are the consequences of a vitelline fistula?
Intestinal contents can leak out of umbilicus
What is Meckel’s diverticulum?
Vitelline duct forms pouch that comes off intestine
Where is Meckel’s diverticulum commonly located along the intestines?
2ft before ileo-ceacal valve
Is Meckel’s diverticulum more common in males or females?
Twice as common in males
What happens to Meckel’s diverticulum during life? Why?
Becomes inflamed
due to secretions from ectopic gastric and pancreatic tissue damaging intestinal wall
How can recanalisation cause congenital defects?
Complete failure of recanalisation
Partial failure of recanalisation
What congenital defect is caused by complete failure of recanalisation?
Atresia
no lumen
What congenital defect is caused by partial failure of recanalsation?
Stenosis
narrowed lumen
Where do atresia and stenosis most commonly occur in the GI tract?
Duodenum
What is pyloric stenosis?
Narrowing of pyloric region of stomach
What causes pyloric stenosis?
Hypertropy of circular layer of smooth muscle in the pyloric region of the stomach
What are the consequences of pyloric stenosis? Why?
Stomach distends, due to build of food within it
Projectile vomiting, due to food not being able to leave stomach into duodenum
How can the fusion of the anterior abdominal wall cause congenital defects?
Failure of fusion of anterior abdominal wall
What congenital defect is caused by failure of fusion of abdominal wall?
Gastroschisis
What are the consequences of gastroschisis?
Parts of GI tract are outside of the abdominal cavity
How is gastroschisis diagnosed?
Ultrasound scans of foetus
When is gastroschisis treated?
After birth
How is gastroschisis treated?
Surgery on baby to return GI tract into abdominal cavity and to close up the anterior abdominal wall
How can physiological herniation cause congenital defects?
Midgut loop doesn’t return into abdominal cavity
phsyiological herniation persists
What congenital defect is caused by persistance of physiological herniation?
Omphalocoele
What are the differences between omphalocoele and an umbilical hernia?
Omphalocoele is covered by peritoneum, umbilical covering only
umbilical hernia is covered by skin, subcutaneous tissue
Because umbilical hernia completed physiological herniation, anterior abdominal wall closed up
whereas omphalacoele didn’t
Why is important to distuinguish between omphalacoele and umbilical hernias?
Omphalacoele is associated with other congenital defects
whereas umbilical hernias are not
What is an umbilical hernia?
Weakness of anterior abdominal wall at umbilicus
allows contents of abdominal cavity to bulge into it
How can the development of the hindgut cause congenital defects?
Cloaca isn’t divided completely
Cloacal membrane doesn’t rupture
Anal canal doesn’t develop
What congenital defect does incomplete division of the cloaca cause?
Hindgut fistulae
What congenital defect does lack of rupture of the cloacal membrane cause?
Imperforate anus
What congenital defect does lack of development of the anal canal cause?
Anal agenesis
