GI Flashcards
Most common type of EA/TEF
Type C- EA with distal TEF ~85%
abnormal formation during 4th week of gestation
usually isolated finding
30-40% with other anomalies
Intestine elongates _____-fold from 5-40 weeks
1000
How long is the intestine at birth?
275 cm
Length doubles in the last __ weeks of gestation
15
When do villi start to form in small intestine?
9 weeks
completed by 16 weeks
Microvilli begin to cover the apical surface of the SI epithelium at ?? weeks
10 weeks
When is meconium present?
16 weeks
When are villi present in the large intestine?
14 weeks
What does the small intestine absorb?
Nutrients
What does the large intestine absorb?
Salt and water
Describe the anatomic development of the GI tract
week 5-9: intestinal tube elongates, herniates into the umbilical cord, undergoes a series of rotations
week 10: tube re-enters abdominal cavity after rotating 270 degrees
when either of these fail –> omphalocele
how much fluid does the fetus swallow in the 3rd trimester
450 mL/day
Pyloric stenosis
Idiopathic hypertrophy of pyloric muscle
1-3/1000 live births
M>F (5:1)
1st born= half of cases
associated with blood groups O and B
Risk of pyloric stenosis
Mother has pyloric stenosis: 19% if boy, 7% if girl
Father has pyloric stenosis: 5.5% if boy, 2.4% if girl
Sibling has pyloric stenosis: 4% if boy, 2.4% if girl
Electrolyte abnormalities in Pyloric Stenosis
dehydration
hypochloremic, hypokalemic metabolic alkalosis
“olive” palpable in epigastric or just right of midline
signs and symptomsof 3-5 weeks of age- nonbilious vomiting, PROJECTILE
US findings of pyloric stenosis
elongation and thickening of pylorus
>3mm and >15mm
string sign
Duodenal atresia
in utero: polyhydramnios, distended duodenum
DOUBLE BUBBLE
No distal air
MC in 2nd part of duodenum
Post natal: bilious emesis in 1st 24 hours, abdominal distention, may pass meconium, dehydration with metabolic acidosis
assoc anomalies: T21 (31%), malro (20%), CHD (30%), annular pacrease (20%)
Mechanism of duodenal atresia
failure of recanalizatin of intestinal tube during 8-10 weeks after lumen obstructed by epithelium at 6-7 weeks
3 types
1: membrane/web
2. fibrous cord with continuity of duodenum
3. complete separation of proximal from distal duodenum
during repair, inspect entire bowel as 15% with multiple atresias
Jejunal atresia
TRIPLE BUBBLE
male = female
Location:
distal ileum>prox jejunum>distal jejunum>prox ileum
mechanism: intrauterine ischemia
causes: volvulus, malrotation, intestinal strangulation at umbilical ring, intestinal perf/peritonitis
Substances: cocaine, pseudoephedrine, nicotine (vasoconstrictive)
malrotation and volvulus
60% cases by 1st month, 90% cases by 1 yr
UGI:
partial obstruction = corkscrew sign
complete obstruction = bird’s beak
Barium enema: cecum in RUQ
Mechanism: incomplete rotation, cecum stops near RUQ, duodenum fails to move behind the mesenteric artery
Ladd’s bands- abnormal tethering that facilitates twisting fo the bowel
Surgery: Ladd’s procedure
clinical assoc: CDH, abdominal wall defects, intestinal atresia, BW syndrome
Meconium ileus
KUB: bowel distention WITHOUT air-fluid levels
Barium enema: microcolon, filling defects
obstruciton of the distal ileum with hyperviscous secretions from mucous glands of the small intestine
adhesion of meconium to intestinal lining due to decreased water content
In utero: dilated loops of bowel, peritoneal calcifications if in utero perf
Post-natal: abdominal distention at birth, sx 24-48 hrs, bilious emesis, failure to pass meconium
Management: hypertonic enema, surgery
90% with meconium ileus have CF, 10-15% of CF have meconium ileus
mechanism of meconium peritonitis
in utero intestinal perforation with spillage of meconium into peritoneum
assoc with intestinal obstruction or mesenteric vascular occlusion
due to meconium ileus, intestinal atresia, gastroschisis, volvulus
imaging: peritoneal calcifications, ascites, obstruction on KUB/fluoro
Hirschprung’s
large colon with no air in rectum
transition zone of barium enema–> narrow rectum relative to colon
DEFINITIVE DIAGNOSIS = BIOPSY
associated with T21, Waardenburg, congenital deafness, 13q deletion, pheochromocytoma, NF, neuroblastoma
Mechanism of Hirschsprung’s
failur to complete cranial to caudal migratin of neural crest cells at 8-10 weeks
aganglionic, no parasympathetic innervation to distal colon
abnormal peristalsis
enterocolitis: sick baby with abdominal distention, vomiting, foul-smelling bloody stools, sepsis
Omphalocele
Male predominance
other anomalie: 50-70%
- trisomies
- cardiac defects
- syndromes: Pentalogy of Cantrell, BW, OEIS
Intestine protected from exposure to amniotic fluid
Giant omphalocele
defect >5 cm
Mechanism of omphalocele
bowel loops fail to return to abdominal cavity by 11 wks
OR
somatic folds fail to complete formation of abdominal wall by 19 wks
Persistent elevated direct hyperbilirubinemia
Most likely due to prolonged TPN use
ALSO think of panhypopit- direct hyperbili due to decreased cortisol
In utero findings for omphalocele
elevated maternal serum AFP
seen on prenatal US 2nd trim
- fetal echo/MRI for coexisting defects
- amnio for chromosomal anomalies
outcome:
10% mortality in isolated omphalocele
60% mortality with multiple anomalies
gastroschisis
increased risk with young maternal age
increased incidence
- olig
- growth restriction
- meconium stained fluid
may development polyhydramnios if obstruction present
MALROTATION present by definition
rarely found with non-GI anomalies
In utero: elevated maternal serum AFP
Primary closure or staged silo
>90% survival
gastric perforation
imaging: isolated gastric pneumonitis, deep/malpositioned OG tube
risk factors:
- perinatal stress
- prematurity
- postnatal steroid exosure
Mechanism:
- spontaneous- overdistenstion
- traumatic- OG placement
Presentation:
- day 2-7
- abrupt increasein abdominal distention, GI bleeding, respiratory distress, shock, sepsis
necrotizing enterocolitis
imaging:
- pneumatosis intestinalis
- portal venous gas (extending 2cm beneath liver capsule
~7% of all premature infants
1-3/1000 live births
M=F
90% = preterm infants
- lower GA = higher risk
Lab findings in NEC
leukopenia
thrombocytopenia
hyponatremia
hypokalemia
metabolic acidosis
DIC
glucose instability
Risk factors for NEC
prematurity= higher risk with lower GA and smaller size
lack of BM feeds
antibiotic exposure
Pathologic features of NEC
Abx: amp/gent, flagyl/cinda if perf or portal venous gas
NEC prognosis
NEC complications
Meconium composition
intestinal secretions
mucosal cells
bile salts
solid portions of amniotic fluid
pepsinogen –> pesin in what cells?
Chief cells
important for protein digestion
stimulated by vagus nerve, histamine, gastrin
stomach acid produced by?
parietal cells
increased gastric pH in neonates –> dec HCl secretion
Preemies»_space; terms > adults
intrinsic factor
responsiblte for vitamin B12 absorption in distal ileum
bile acids
decreased in neonate
reach adult values at ~2 months
disaccharidases
maltase
sucrase
lactase
in the brush border
maltose –> glucose + glucose (adult = 28 wks)
sucrose –> glucose + fructose (adult = 28 wks)
lactose –> glucose + galactose (adult = 36 wks)
colonic salvage pathway
important for carb digestion
colonic bacteria help ferment malabsorbed carbs
cholecystokinin
CCK
hormon that trigger release ofp ancreatic juice and bile
decreases gastrin secretion
secretin
hormone that stimulates pacrease to release bicarb –> slows gastric emptying
gastrin inhibitory peptide
GIP
hormone that is stimulated by protein and fat
slows gastric emptying
decreases gastrin
motilin
hormone that increases gastric emptying
erythromycin = motilin agonist
benefits of early feeding
physiologic and clinical
increased intestinal blood flow
increased gut barrier defense –> earlier intestinal closure
increased enzyme maturation
increased gut hormone regulation
increased motility
earlier attainment of full enteral feedings
reasons for small left colon/microcolon
maternal diabetes - MOST COMMON
maternal hypothyroidism
maternal toxemia –> mag exposure
prematurity
rare complication of cecal perforation
rectum is normal on barium enema
risks for meconium plug
diabetic mothers
antenatal exposure to magnesium sulfate
cystic fibrosis –> more common meconium ileus
small left colon syndrome
subset of infants with meconium plug that demonstrate transition zone between dilated proximal bowel and normal-decreased distal colon at SPLENIC FLEXTURE
transition zone = rectosigmoid region in Hirschsprung
idiopathic neonatal hepatitis
multinucleated giant cells
increased alpha-fetoprotein
SIP
more likely smaller/more immature
occurs earlier postnatally (1st week)
unlikley to be fed
more likely to have PDA/tx with indocin
more likely to have received vasopressor support
more likley to have received surf/ventilation
Meds: Indomethacin, early hydrocortisone, vasopressors
associated with chorio
abdominal distension with black-bluish discoloration, hypotension, pneumoperitoneum (NO pneumatosis or portal venous gas)
most common location of NEC
terminal ileul
proximal colon
lab findings in NEC
leukopenia»_space; leukocytosis
thrombocytopenia
hyponatremia
hypokalemia
metabolic acidosis
DIC
glucose instability
NEC onset:
26 weeks
>31 weeks
full term
23 days
11 days
3 days
intestinal strictures post NEC
mostly in colon L > R
median presentation = 5 weeks
worse prognosis with short bowel syndrome
colon resected
no IC valve
> 25 cm bowel resected with IC valve
> 40 cm without IC valve
if not IC valve, needs ~30-45cm of intestinal length
echogenic bowel on fetal US
Chromosomal abnormalities - T21
Congenital infection - CMV
Meconium ileus
Meconium peritonitis
Atresia or volvulus
Swallowed blood
Proximal bowel obstruction associated with polyhydramnios
recurrence rate of NEC
6%
recurrence risk of neonatal hemachromatosis
90% in pregnancies subsequent to the index case
most common intestinal atresia
jejual/ileal
2nd MC is duodenal
most to least common site of intestinal atresias
distal ileum > proximal jejunum > distal jejunum > proximal ileum
polyhydramnios in 30% jejunal atresias, less common in ileal atresia
MC cause of ileal/jejunal atresia
intrauterine ischemia due to:
- volvulus
- malrotation
- intestinal strangulation at the umbilical ring
- intestinal perforation
- vascoconstrictive drugs including cocaine, pseudoephedrine, nicotine
when does duodenal atresia occur?
during intestinal development
most common cause of an abdominal flank mass
hydronephrosis
progressive familial intrahepatic cholestasis
alpha 1 anti-trypsin deficiency
first imaging study for concern of biliary atresia
liver US
then HIDA scan
percutaneous biopsy prior to surgery
progressive familial intrahepatic cholestasis
3 types, AR
rapid cholestatic hepatitism, FTT, pruritis
type 3: presents in adolescence
type 1&2: GGT is normal
