Acquired Disorders of the Gastrointestinal Tract Necrotizing enterocolitis (NEC) most common gastrointestinal (GI) emergency in premature infants □ Clinical features □ Incidence, ∼12% of infants born at <1500 g, 30% mortality □ Postnatal age of onset and incidence inversely related to birth weight and gestational age □ 90% of infants with NEC premature □ Term, late preterm infants infrequently develop NEC; risk factors (associated with bowel ischemia) include intrauterine growth restriction (IUGR) and small for gestational age (SGA), birth asphyxia, congenital heart disease, gastroschisis, polycythemia, hypoglycemia, sepsis, exchange transfusion, ± umbilical lines □ Can occur in epidemics □ Occurs more frequently in African-American infants than white infants □ More common following initiation of enteral feeds □ Breast milk and established feeding guidelines—protective factors □ 50% require surgery

1. 254
Gastrointestinal Bleeding
See Table 43.1.
NECROTIZING ENTEROCOLITIS
□
Necrotizing enterocolitis (NEC) most common gastroin-
testinal (GI) emergency in premature infants
□
Clinical features
□
Incidence, ∼12% of infants born at 1500 g, 30% mor-
tality
□
Postnatal age of onset and incidence inversely related
to birth weight and gestational age
□
90% of infants with NEC premature
□
Term, late preterm infants infrequently develop NEC;
risk factors (associated with bowel ischemia) include
intrauterine growth restriction (IUGR) and small for
gestational age (SGA), birth asphyxia, congenital heart
disease, gastroschisis, polycythemia, hypoglycemia,
sepsis, exchange transfusion, ± umbilical lines
□
Can occur in epidemics
□
Occurs more frequently in African-American infants
than white infants
□
More common following initiation of enteral feeds
□
Breast milk and established feeding guidelines—protec-
tive factors
□
50% require surgery
□
Predictor of neurodevelopmental morbidity
□
Positive blood cultures in one-third
□
Likely multiple risk factors—bowel ischemia, immaturity
of immune system, enteral feeding
□
Clinical presentation
□
Lethargy, apnea, abdominal distention, erythema, de-
creased bowel sounds, metabolic acidosis from lactate
accumulation, peaceful tachypnea due to abdominal
distention and metabolic acidosis, poor perfusion with
delayed capillary refill
□
Diagnosis
□
Suspect with clinical features; laboratory values can re-
veal neutropenia, thrombocytopenia, hyponatremia.
□
Abdominal x-ray—can reveal fixed loop, stacking of
loops, pneumatosis, portal venous air, perforation
□
Treatment
□
NPO, decompress GI tract with Replogle tube, fluid resus-
citation,avoiddopamine(canworsenbowelnecrosisfrom
vasoconstriction),broad-spectrumantibiotics,respiratory
support if apneic, surgical resection of necrotic bowel
SHORT BOWEL SYNDROME
□
Occurs following bowel resection to treat NEC (most com-
mon), midgut volvulus, omphalocele, aganglionosis, je-
junal or ileal atresia, gastroschisis
□
Most frequent cause of intestinal failure in neonates
□
Clinical features depend on length of remaining bowel,
location of lost bowel
□
Complications
□
Malabsorption of nutrients
□
Gastric hypersecretion
□
Small bowel bacterial overgrowth
□
Intestinal adaptation difficulties
□
Cholestatic liver disease typically from chronic use of
parenteral nutrition
□
Catheter-related complications
□
Enterocolitis
□
Management
□
Parenteral nutrition to supply adequate calories
□
H2 blockers or proton pump inhibitors to suppress acid
secretion
□
Intermittent treatment with antibiotics for bacterial
overgrowth
□
Enteral feeds to help with intestinal growth and adapta-
tion—small volumes of elemental formula with medi-
um-chain triglycerides
□
If missing ileocecal valve at high risk for diarrhea, fat
and vitamin B12 malabsorption, need vitamin B12 sup-
plementation
Acquired Disorders of the
Gastrointestinal Tract
REBECCA ABELL and MEGAN E. GABEL
43
Table 43.1 Causes of Gastrointestinal (GI) Bleeding in
the Neonate
Upper GI Bleeding Lower GI Bleeding
Swallowed maternal blood Milk protein allergy, allergic colitis
Vitamin K deficiency Hirschsprung disease
Stress gastritis or ulcer Necrotizing enterocolitis
Acid-Peptic Disease Intussusception
Vascular anomaly Gastrointestinal duplication
Coagulopathy Duodenal web
Mallory-Weiss tear Anal fissure
Bowel obstruction Coagulopathy
Milk protein allergy Volvulus
Infectious colitis
Meckel diverticulum
Presentation of Upper GI
Bleeding
Presentation of Lower GI
Bleeding
Hematemesis Bright red blood in the stool
Coffee ground emesis Tarry stools
Melena