Patients with liver disease are at risk to develop varices, but about half of upper GI bleeding in patients with known varices is from another source. Aspirin also inhibits platelet adhesion, which may aggravate bleeding of any cause. Recent ingestion of aspirin, other NSAIDs, or alcohol predisposes to gastric mucosal injury. Bleeding from inflammatory bowel disease or a Meckel's diverticulum is more likely in a child or young adult. For example, ischemic colitis, cancer, arteriovenous malformations, and diverticulosis are associated with advanced age, whereas none is a probable consideration in a 25-year-old. Age of the patient makes some diagnoses more or less likely. Some features of the history may be diagnostically helpful. Red blood per rectum usually is a sign of lower GI bleeding, although it may come from profuse upper GI bleeding, such as from esophageal varices or an eroded artery in a peptic ulcer. Vomiting either red blood or “coffee ground” material (which is caused by the action of gastric acid on blood) typically signifies an upper GI source but also can result from swallowed blood from the nose or respiratory tract. Brisk bleeding may cause vomiting of blood (hematemesis) or appear as red blood per rectum (hematochezia). Although melena usually results from upper GI bleeding, it can come from a source as low as the right colon. Melena, or black stool, may develop with as little as 50 ml of blood loss from the GI tract per day. Iron supplements can also make stools test heme positive. True melena is pitch black, tarlike, and sticky and has an odor that is not soon forgotten. Also in newborns, passage of stools can cause small tears in anorectal tissue and give rise to fissures that result in small amounts of blood coating the stool.īismuth compounds (e.g., Pepto-Bismol) and iron supplements can turn stools black. Milk protein allergy may present as bloody mucous stools and increased stool frequency. Premature infants (< 35 weeks) are at higher risk for necrotizing enterocolitis. In infants, careful examination of the perineum may reveal estrogen-withdrawal vaginal bleeding in females or the presence of small fissures around the anus. Painless lower GI bleeding implies a Meckel diverticulum, whereas associated abdominal pain suggests intussusception in infants and toddlers, inflammatory bowel disease in children and adolescents, or infectious causes if associated with diarrhea. Endoscopy or magnetic resonance (MR) enterography should be considered if inflammatory bowel disease is suspected. Growth failure may suggest inflammatory bowel disease. Eosinophils seen on Wright stain of the stool suggest milk protein allergy in infants. Stool should be examined for the presence of leukocytes, ova, and parasites, especially Giardia lamblia. A history of frequent health care system encounters or prolonged antibiotic exposure will predispose to Clostridium difficile enterocolitis. If there is associated diarrhea, evaluation for bacterial enteritis may begin with stool nucleic acid testing or culture for Salmonella, Shigella, Yersinia, Campylobacter, Escherichia coli, and other species. A mass may sometimes be palpable in the right lower quadrant or on rectal examination. The classic description of a “currant jelly” stool in an infant or toddler with intermittent irritability strongly suggests intussusception. Nocton MD, in On Call Pediatrics, 2019 Lower Gastrointestinal Bleeding (Hematochezia and Occasionally Melena)
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