white blood cell (WBC) differential to assess the hemoglobin level and check for eosinophilia in cases which are severe, refractory, or where there is concern for anemia Examination of stool for blood, fecal leukocytes, bacterial culture should be performed on infants who have proven refractory to dietary therapy or if there is a known infectious exposure C difficile may also be considered though infants may be colonized with this organism Infants who have milk-protein sensitivity colitis will characteristically have leukocytes seen on fecal smear and eosinophils may also be present In cases of suspected food impaction, a two-view CXR is often obtained but often does not identify the nonradiopaque food item Treatment consists of identifying and eliminating the offending protein from the diet There is generally improvement in symptoms within 72 hours of the dietary change, though complete resolution may take weeks Guaiacpositive stools may also persist for several weeks Mothers of breast-feeding infants may be asked to eliminate milk protein or other suspected culprit proteins from their diet, but breast-feeding can often be continued Infants receiving cows’ milk–based or soy protein formulas should be changed to a formula containing casein hydrolysate as the protein source Nutramigen, Pregestimil, and Alimentum are currently available in the United States Occasionally, in patients with severe allergic colitis or FPIES, an amino acid–based elemental formula, such as Neocate or Elecare, is recommended Children with EE presenting with food impaction require removal of the impaction by either gastroenterology, surgery, or ENT, depending on institutional protocol Clinical Indications for Discharge or Admission Most children can be safely discharged from the emergency department Parents should be counseled that infants who respond to dietary elimination require follow-up and generally should not be challenged with a milk- or soybased formula until year of age Allergic symptoms may also change with age, such as the development of vomiting and diarrhea in addition to GI bleeding Infants with evidence of persistent gross bleeding weeks following formula change require further evaluation and potential consideration for a more intensive dietary change or workup for an alternative diagnosis Children with vital sign instability, significant failure to thrive, failure to gain weight on amino acid–based formulas, or significant anemia should be