3) Understand the management and prognosis of eosinophilic gastroenteritis. CASE INFORMATION: A 38 year-old woman presented to the ER with vomiting and diarrhea for four weeks. She experienced 6-8 watery, non-bloody stools per day; vomiting after consuming any food or liquid; and a``pulling sensation'' across the lower abdomen. One week after the onset of symptoms the patient was admitted to the hospital, rehydrated, and discharged with a diagnosis of acute gastroenteritis. The symptoms worsened soon after discharge, and the patient was readmitted to the hospital. Evaluation included routine stool cultures and ova and parasites. The patient was treated empirically with levofloxacin and metronidazole and was discharged home. Stool cultures were later found to be negative. The patient's symptoms quickly worsened and she presented again to the ER. Past medical history was remarkable for asthma and lactose intolerance. On physical examination, BP = 115/62, P = 110, and T = 99.18F. Abdominal examination revealed a moderately distended abdomen with shifting dullness and mild tenderness to palpation in the upper abdomen. The remainder of the examination was unremarkable. The white blood cell count was 15,600 with 55.3% eosinophils; the hemoglobin was 8.9. CT of the chest, abdomen, and pelvis revealed a thickened terminal ileum and cecum, ascites, and bilateral small pleural effusions. Paracentesis was performed. The peritoneal fluid revealed 1,920 white blood cells with 3 neutrophils, 12 lymphocytes, and 85 eosinophils. Ascites fluid albumin was 3.3; the serum-ascites albumin gradient was 1.2. Upper and lower endoscopy revealed only melanosis coli. Biopsy of the duodenal mucosa revealed lymphocytic and eosinophilic infiltration. The patient was treated with prednisone. Her symptoms improved and she was discharged home. IMPLICATIONS/DISCUSSION: Eosinophilic Gastroenteritis (EG) is a rare disease whose etiology is unknown, though it may be a Type I hypersensitivity reaction. Patients with EG present a range of symptoms from nausea, vomiting, and diarrhea, to ascites and bowel obstruction. The symptom complex is determined by the degree of eosinophilic infiltration of the gastrointestinal tract. The diagnosis of eosinophilic gastroenteritis requires the presence of gastrointestinal symptoms, eosinophilic infiltration of one or more areas of the gastrointestinal tract on biopsy, absence of eosinophilic involvement of multiple organs outside the gastrointestinal tract, and absence of parasitic infection. Eosinophilic gastroenteritis without ascites is treated with cromolyn; the presence of ascites requires glucocorticoid treatment. More than 90% of patients respond quickly to treatment. The relapse rate is high with cessation of treatment (>33%). Those who relapse often require maintenance therapy with glucocorticoids.