Step 1

Gastrointestinal 1

A four-week-old former full-term infant is brought to the emergency department by his parents for vomiting. The mother explains that she exclusively breastfeeds the infant and that for the past two weeks he has vomited after every meal but still appears hungry. She describes that the vomiting has increased in intensity over the last week, and the infant now forcefully vomits. Upon further questioning, the mother describes the emesis as nonbilious and consisting of only breastmilk. However, today the emesis contained what appeared to be bright red blood. The patient's mother received routine prenatal care, and the delivery and post-natal course were uneventful. On physical examination, the infant is afebrile and appears somnolent, the fontanelle appears slightly sunken, lung sounds are clear to auscultation, and a 1 cm mass is palpated in the epigastric area of the abdomen. Serum laboratory results reveal the following:

  • Sodium: 138 mEq/L
  • Potassium: 2.5 mEq/L
  • Chloride: 88 mEq/L
  • Bicarbonate: 30 mEq/L
  • Creatinine: 0.2 mg/dL
  • BUN: <5 mg/dL

What is the most likely source of bleeding in this patient?

  • A) Deficiency of clotting factors
  • B) Ingestion of foreign body
  • C) Invasive bacterial infection
  • D) Tear in the esophageal mucosa
  • E) Ulceration of gastric mucosa


Ardian Latifi


Dr. Ted O'Connell

Last updated

Dec 29, 2023


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