A 7-day-old premature infant born at 26 weeks of gestation now has a grossly bloody stool, abdominal distention, and increasing oxygen requirements.
- Abdominal series
- Fiberoptic endoscopy
- Apt test
- Routine stool culture
- Barium enema
Explanation
Swallowed maternal blood can be differentiated from neonatal hemorrhage by the Apt test, which distinguishes fetal hemoglobin from adult hemoglobin based on the specimen’s reaction to alkali (fetal hemoglobin is unchanged, whereas adult hemoglobin changes to hematin). Infants may swallow blood during delivery or from a cracked nipple during breast-feeding.
Necrotizing enterocolitis is a life-threatening condition seen mostly in premature infants. Although the precise etiology is unknown, contributing factors include GI tract ischemia, impaired host immunity, the presence of bacterial or viral pathogens, and the presence of breast milk or formula in the gut. Findings include bloody stools, abdominal distension, hypoxia, acidosis, and emesis. The initial diagnostic test of choice is plain film radiographs. The characteristic finding in necrotizing enterocolitis (NEC) is pneumatosis intestinalis; free air in the peritoneum may also be seen. Perforation is a surgical emergency, otherwise observation and antibiotics are indicated.
Enterohemorrhagic Escherichia coli are pathogens found in poorly cooked beef, and some have been responsible for outbreaks of bloody diarrhea that were well-publicized in the media. These organisms secrete shiga toxin. Routine stool cultures do not isolate this particular pathogen; the laboratory must use sorbitol-MacConkey agar to isolate the bacteria. Enzyme assays for shiga toxin are becoming available as well.
Forceful emesis can result in small tears in the esophagus, termed MalloryWeiss syndrome. This is usually a benign condition, only occasionally resulting in significant blood loss. In a patient who is otherwise stable, diagnostic procedures are not indicated.
Peptic ulcer disease can result in hematemesis and melena, along with the typically epigastric abdominal pain. Children can have both chronic and acute blood loss associated with ulceration. Fiberoptic endoscopy is the diagnostic method of choice. An upper GI series can sometimes reveal an ulcer as well. While H pylori serum assays are available, they have limited usefulness in children.