Gastroenterology Flashcards
Most common complication medical NEC
strictures
Reducing volvulus = Ladd’s procedure
turn bowel COUNTERCLOCKWISE. remove appendix, separate Ladd’s bands that connect intestine to mesentery, situate bowel in abdomen with cecum in LLQ, duodenum on R
Risk factors for NEC
indomethacin, postnatal steroids, vasopressors, mechanical ventilation / surfactant, maternal chorio
Gastroschisis risk factors
YOUNG maternal age, smoking, alcohol, illicit substance use, OTC vasoactive meds, salicylates
Gastroschisis concurrent anomalies?
Genetic causes?
10% have GI anomalies (intestinal atresia/stenosis). IUGR affects 20-60%.
Gene polymorphisms of endothelial nitric oxide synthase, intracellular adhesion molecule 1, atrial natriuretic peptide
Omphalocele associate anomalies
50% have cardiac, urogenital, brain, spina bifida
OEIS syndrome
omphalocele, cloacal exstrophy, imperforate anus, spinal defects
Syndromes associated with omphalocele
T13, 18, Beckwith Wiedemann. OEIS
Recurrence risk of neonatal hemochromatosis in subsequent pregnancies?
90%. Giving IVIG at 18 weeks significantly decreases risk
Gastric pH is increased in neonates due to ______
decreased HCl secretion
Polyhydramnios occurs in ______ of fetuses with jejunal atresia. Is less common in fetuses with ileal atresia
1/3
What atresias are more common (in decreasing order)
Distal ileum > proximal jejunum > distal jejunum > proximal ileum
Schwachman Diamond Syndrome (genetic)
rare AR d/o (1 in 75k)
90% of cases associated with mutation on chromosome 7q11
Important role in maturation of 60s ribosomal subunit and ribosomal assembly
Schwachen Diamond clinical presentation
infancy - BM failure (neutropenia, anemia, thrombocytopenia), pancreatic dysfunction, recurrent infections, skeletal abnormalities. Neutropenia is most common hematologic abnormality. Increased risk of myelodysplastic syndrome and leukemia
Pathophysiology of biliary atresia?
viral triggered immune reactions during development
Meconium plug is due to _____?
functional immaturity and hypo-motility of COLON - immaturity of myenteric plexus nerve cells (meconium ILEUS involves distal ileum).
Barrier defenses of GI system?
adaptive and innate
Secretory IgA, intestinal mucins, antimicrobial peptides, pathogen recognition receptors, immune cells
Heme oxygenase converts _____
heme –> biliverdin
Biliverdin reductase converts biliverdin to bilirubin
Neonatal hemochromatosis
iron deposited in liver and other tissues –> stillbirth. Causes IUGR, preterm birth. Liver failure, cardiac impairment. Normal/elevated LFTs, low fibrinogen, anemia, thrombocytopenia, high ferritin
HLH
abnormally hyper-activated T-cells and macrophages. But also have neutropenia and low natural killer cell counts.
Dx: finding hemophagocytosis in samples of bone marrow, spleen, or lymph node
When does gastric acid production reach adult levels? What are they at birth?
3 months of age
Birth: gastric pH is neutral to alkaline (alkaline amniotic fluid)
Benefit of medium chain fatty acids?
can directly enter portal venous system from enterocyte
Microcolon associations?
IDM, maternal hypothyroidism, maternal toxemia, prematurity
Esophageal duplication cyst complication?
can become malignant in future
Omphalocele (risk factors)
ADVANCED maternal age, 30% have abnormal karyotype (T13, 18, 21). 50-70% of affected patients have associated congenital anomalies, 10% B-W syndrome (omphalocele, gigantism, macro glossia, hypoglycemia 2/2 pancreatic hyperplasia)
Omphalocele genetic causes
pituitary hemobox 2, insulin-like growth factor 2, cyclin-dependent kinase inhibitor 1C, methylenetetrahydrofolate reductase gene polymorphism (677C-T)
Most common complication of Hirschsprung’s disease
acute bacterial enterocolitis
Causes of duodenal vs jejunal / ileal atresias
Duodenal: failure to re-canalize during 8-10 weeks gestation (obliterated during 6-7 weeks)
Jejunal/ileal: vascular accident
MCC abdominal flank mass
hydronephrosis
Meconium plug syndrome risk factors
IDM, mag sulfate, CF
Innate immune system in GI tract
Intestinal mucins: secreted by goblet cells, thick physical bacteria
Secretory IgA: binds to bacteria, prevent from penetrating epithelial layer
Antimicrobial peptides: produced by Paneth cells, but also goblet and epithelial cells
Pathogen recognition receptors: on surface or in cytoplasm of epithelial cells
Immune cells: dendritic, macrophages, NK cells, NK T- cells, gamma- T cells
Cellular risk factors for NEC
NEC risk factors
Loose tight junctions
Thin goblet cell secretions
Few paneth cells (for antimicrobial peptides), decreased IgA, increased inflammatory cytokines, altered TLR4 signaling
HLH cell difference compared to hemochromatosis
HLH has NEUTROPENIA and low natural killer cell counts (compared to neonatal hemochromatosis)
