Developmental d/o of GI tract

Question 1

Meckel’s diverticulum 1

Answer 1

• Results from partial persistence of the omphalomesenteric duct
• D/o of 2s: 2% of population, usually seen in first 2 yrs of life, located 2 ft from ileocecal valve
• 50% of these diverticula have ectopic gastric mucosa (capable of producing both acid and gastric nzs)
• This can be seen in a scan of Technetium uptake (taken up by gastric mucosa)
• Clinical presentation: rectal bleeding, vomiting-bowel obstruction, acute abdominal pain
• Most common clinical: sudden onset of painless rectal bleeding w/ soft non-distended abdomen

Question 2

Meckel’s diverticulum 2

Answer 2

• Rectal bleeding: hemorrhage due to peptic ulceration of mucosa, usually ASx w/ passage of red/burgundy stool
• Vomiting-bowel obstruction: the diverticulum may invaginate, pulling ileum inside it and causing an obstruction (intussusception)
• This will lead to ab pain, emesis (often bilious) and dissension
• Acute ab pain/peritonitis: its possible for the diverticulum to become inflamed, producing a syndrome similar to appendicitis
• Perforation is possible, which can lead to peritonitis, abscess formation

Question 3

Intestinal obstruction in newborn 1

Answer 3

• Obstruction + continued secretion leads to increased luminal pressure
• This can cut off blood flow, leading to necrosis and perforation of the intestinal wall and peritonitis
• In newborn complete obstructions are characterized by onset of Sx 24-48 hrs after birth
• Incomplete obstructions will not arise until later

Question 4

Intestinal obstruction in newborn 2

Answer 4

• Hx: polyhydramnios (excess amniotic fluid b/c fetus cannot swallow the fluid due to bowel obstruction), CF
• Toxemia, bleeding, viral infections, maternal diabetes all increase risk for congenital abnormalities, including bowel obstruction
• Signs/Sx of newborn: vomiting (often bilious), abdominal dissension, delayed or absent meconium passage, increased gastric aspirate (>15ml)

Question 5

High vs low obstructions

Answer 5

• High: obstructions in upper part (above ileum) of GI tract
• Associated w/ early onset emesis (first 24 hrs) and relatively mild ab distension
• Xray: small number of distended loops of bowel w/ absent or decreased distal gas
• Lower: obstructions in the lower part of the ileum-colon may have delayed vomiting (after 24 hrs) and significant dissension may proceed emesis
• Xray: multiple air filled loops of bowel, barium enema show collapsed colon (not receiving poop)

Question 6

Malrotation and midgut volvulus 1

Answer 6

• Normal rotation is not completed and the cecum resides in abnormal site (UR quad) near duodenum
• This leads to abnormal placement of the mesenteric ligaments (ladd’s bands) which can be laid across the duodenum resulting in obstruction
• The horizontal mesenteric base is short (instead of broad)

Question 7

Malrotation and midgut volvulus 2

Answer 7

• The SMA and vein run thru the mesenteric base, but when its short there is a greater risk for twisting of this base, which can result in cutting off the blood supply from the SMA
• This results in volvulus and is an emergency
• Clinical findings: usually in infants, they present w/ acute onset of bilious emesis followed by passage of bloody stool
• Dx via plain films (upper obstruction)

Question 8

Duodenal atresia

Answer 8

• Often seen w/ down syndrome, imperforate anus, trachea-esophageal fistula, prematurity, and congenital heart disease
• The lumen of duodenum is obliterated form week 5-6 and recanalized during weeks 8-10
• This process may be completely prevented (atresia) or incompletely prevented (stenosis)
• Most are distal to ampulla of vater, thus early onset of bilious emesis is most common presentation
• Ab distension absent or mild
• Plain films show characteristic dissension of stomach and proximal duodenum w/ absent distal gas (double bubble sign)

Question 9

Jejunoileal atresia

Answer 9

• Associated w/ CF, caused by intrauterine volvulus of a part of bowel
• The necrotized area is resorbed which produces a blind proximal and distal intestinal segments
• Clinical findings: abdominal dissension followed by bilious emesis, late/absent passage of thick meconium
• Xray: multiple loops of dilates bowel w/ absent gas distal to obstruction, unused colon

Question 10

Hypertrophic pyloric stenosis

Answer 10

• Occurs 3-12 wks after birth, due to a thickening of the pyloric channel
• Clinically: non-bilious, projectile emesis (most often after feeding), weight loss, dehydration, electrolyte disturbances (hypochloremic hypokalemic metabolic acidosis), jaundice, hyper peristaltic waves, palpable “pyloric olive”
• Dx: clinical, upper GI series, but most important is abdominal ultrasound