Development of the Alimentary System Flashcards
Omphaloceles
Large swelling in the umbilical cord covered in amnion because the intestinal loop failed to return to the abdominal cavity and stayed in the umbilical cord.
Gastroischisis
Defect in the anterior abdominal wall allows extrusion of abdominal viscera just hanging outside the body.
Ileal (Meckel’s) diverticulum
Outpouching on the ventral border of the ileum close to the ileocecal junction because a remnant of the vitelline/omphaloenteric duct/yolk stalk persists.
Usually degenerates, but may get an ulcer, get inflamed, have a fistula going into the umbilicus, vitelline cysts, volvulus, fibrous cord.
Development of imperforate anus
Persistent anal membrane separates the anal canal form the exterior.
Results in many anorectal malformations.
Anal agenesis
Anal canal ends blindly or ends with a fistula to the perineum due to failure of the urorectal septum to separate the cloaca.
Anal stenosis
Canal is narrowed because the urorectal septum grew too far dorsally
Anorectal agenesis
Most common anorectal malformation.
May end blindly or have a fistula to the bladder (rectovesicle fistula) or urethra (rectourethral fistula) or vagina (rectovaginal fistula), due to abnormal formation of the urorectal septum.
Megacolon (HIrschsprung’s disease)
Absence of autonomic ganglia (myenteric & submucosal plexus) of colon causes severe dilation of part of the colon (megacolon) as the bolus tries to move down.
Results because neural crest cells fail to migrate caudally.
Annular pancreas
The ventral pancreatic bud rotates in the wrong direction, causing it to fuse with the dorsal bud ventrally and dorsally –> pancreas tissue encircles compressing the duodenum.
May be associated with duodenal atresia.
Duodenal atresia
The duodenum doesn’t recanalize –> “double bubble” sign on an ultrasound
Duodenal stenosis
Incomplete recanalization or annular pancreas constricts the duodenal opening
Hypertrophic pyloris stenosis (HPS)
Hypertrophy of the circular smooth muscle at the pyloric sphincter narrows the pyloric lumen -> obstructs food passage
> projectile vomit without bile
Esophageal atresia
Tracheoesophageal septum deviates too far dorsally, causing the esophagus to end blindly.
Associated with:
VACTREL
Respiratory distress
Polyhydramnios: excess amniotic fluid due to inability to swallow
Esophageal stenosis - what is it and what is it caused by?
Narrowing of the esophagela lumen due to incomplete recanalization
Esophageal cysts/webbing due to
Incomplete recanalization
Short esophagus can cause what type of hernia?
Congenital hiatal hernia- stomach displaced through the esophageal hiatus
Manifestations of hypertrophic pyloric stenosis in infants
- Projectile vomiting (no -bile)
- Dehydration
- May come with esophageal atresia
Why is there no bile in the vomit of infants with hypertrophic pyloric stenosis?
The bile duct is caudal of the pyloric region of the stomach .
Sign of duodenal atresia
Infant vomits hours after birth and it contains bile.
Does vomit from annular pancreas contain bile?
Yes.
Congenital Umbilical Hernia
The gut went in but herniates back out into the umbilical area, but it’s covered with skin.
3x more common in women
What is the cause of aganglionic megacolon?
Failure of neural crest cells to migrate into the wall of the colon in the 5th-7th wks.
Rectal atresia
Rectum and anal canal are separated by a wedge of fibrous tissue.
Occurs because of abnormal recanalization or compromised blood supply.
Most common anorectal malformation
Anorectal agenesis.
