Lower GI bleeding, presenting as melena or hematochezia, can occur anywhere distal to the ligament of Treitz, including the small intestine, colon, rectum, and anus. Causes of lower GI bleeding vary by age (Table 71-2). Although bloody stools are a common complaint, encompassing 0.3% of pediatric ED visits overall, most causes are relatively benign and self-limited.4 The actual bleeding source, however, may be difficult to identify. Melena typically indicates a more proximal source and occurs when blood has been present in the GI tract for a prolonged period of time, resulting in breakdown of hemoglobin.19 Small-volume hematochezia is typically from the distal colon or anus, although large-volume rectal bleeding can result from lesions any place along the GI tract if bleeding is brisk.
TABLE 71-2Causes of Lower Gastrointestinal Bleeding (BY AGE) |Favorite Table|Download (.pdf) TABLE 71-2 Causes of Lower Gastrointestinal Bleeding (BY AGE)
Ingested maternal blood
Nodular lymphoid hyperplasia
A common cause of lower GI bleeding in children is infectious enterocolitis. Enterocolitis occurs among children of all ages and can result in abdominal pain, fever, and bloody stools. Common pathogens implicated in bloody diarrhea include Salmonella, Shigella, Campylobacter jejuni, Yersinia enterocolitica, Escherichia coli, Clostridium difficile, and Entamoeba histolytica.4 Although most enterocolitis is self-limited, rare complications such as hemolytic uremic syndrome can occur; thus, children with infectious enterocolitis and bloody diarrhea may require additional testing with close follow-up. Diagnosis can be made by stool culture or antigen testing. Most cases of infectious enterocolitis in otherwise healthy children do not require specific treatment; avoid antimotility agents. Antimicrobial therapy may worsen the clinical course in some cases and are only recommended for patients with documented Shigella, Campylobacter, C. difficile, or E. histolytica enterocolitis as well as very young or immunocompromised children and those with sepsis or septic shock.20
Necrotizing enterocolitis (NEC) is a rare but serious cause of neonatal lower GI bleeding. Although it is most common in premature newborns in the intensive care unit, neonates may present to the ED. These infants often have a history of prematurity, significant anoxic stress at birth, or cyanotic congenital heart disease, all leading to gut hypoperfusion.21,22 Infants with NEC appear ill with lethargy, abdominal distension, vomiting, and bloody stools. Abdominal radiographs may reveal distended loops of bowel, pneumatosis intestinalis, or bowel perforation. Treatment involves fluid resuscitation, bowel rest, broad-spectrum antimicrobials, and emergent surgical consultation.21
Children with Hirschsprung disease can develop toxic megacolon and may present acutely ill with abdominal distension, fever, explosive diarrhea, hematochezia, and abdominal pain. Toxic megacolon may be the initial presentation of Hirschsprung disease, but may also occur after surgical resection of the aganglionic segment, particularly in children with longer segment disease or Down syndrome.23 Intestinal dilation with air–fluid levels can be seen on plain abdominal radiography, often with an intestinal cutoff sign (abrupt cutoff of intestinal distension at the pelvic brim, Fig. 71-3).24 Treatment involves bowel decompression, hydration, and broad-spectrum antibiotics.23
Intestinal cutoff sign seen in a child with toxic megacolon. This child had previously undergone resection of his aganglionic colon segment. Note the massive intestinal distension. (Used with permission from Dr. Thomas J. Abramo, Pediatric Emergency Medicine, Vanderbilt University Medical Center.)
Obstructive disorders of the intestine can also cause lower GI bleeding, usually small in volume, secondary to ischemia. Intussusception, the most common cause of obstruction, typically occurs in children younger than 2 years of age. The classic presentation is intermittent colicky abdominal pain and vomiting; some children present with a generalized illness, malaise, or altered mental status. Intussusception can occur anywhere within the bowel, but most commonly at the ileocecal junction. A sausage-shaped abdominal mass may be palpated in the right lower quadrant or anywhere along the ascending or transverse colon, depending on the extent of bowel telescoping. Bleeding from an intussusception is classically described as “currant-jelly,” although this appearance is present in only approximately 10% of confirmed cases of intussusception.25 Hematochezia, from bowel ischemia, is a late and ominous finding.4 More commonly, bleeding is only detectable by guaiac testing, and lack of blood in the stool does not exclude intussusception. Abdominal radiographs may show a classic “target sign” or paucity of bowel gas in the right lower quadrant, but may also be normal.21 Ultrasound is a more sensitive and specific modality for the diagnosis of intussusception, with the added benefit of lacking ionizing radiation.26 With the growing role of ultrasound, air-contrast enema is less often used for the primary diagnosis, but remains the therapeutic modality of choice for uncomplicated intussusception. Complications such as failure to reduce the intussusception or bowel perforation with possible tension pneumoperitoneum can occur, necessitating surgical consultation availability.
Volvulus can also present with rectal bleeding from bowel ischemia, most commonly in neonates with congenital malrotation of the midgut; typical presentations include bilious vomiting, abdominal distension, and refusal to feed. Abdominal radiographs may reveal a paucity of gas in the abdomen with a “double bubble sign,” which is a foci of gas seen in the dilated stomach and duodenum. An upper GI contrast study is the diagnostic study of choice. Fluid resuscitation, antimicrobials, and emergent surgical reduction of the volvulus are critical to preserve bowel viability. Duplication of the bowel can also result in bowel ischemia and bleeding from intussusception, volvulus, or expansion of the duplication.4
Meckel diverticulum, resulting from incomplete obliteration of the omphalomesenteric duct during fetal development, is a common cause of otherwise asymptomatic bleeding in the small intestine. The “rule of 2's” characterizes the classic Meckel diverticulum as 2 inches long, occurring within 2 ft of the ileocecal valve, and present in approximately 2% of the population.4,27 If the diverticulum contains ectopic gastric mucosa, ulceration and massive (typically, painless) bleeding can occur. For diagnosis, a radionuclide scan with technetium-99m pertechnetate, or “Meckel scan,” utilizes a radioisotope that preferentially binds to gastric mucosa.4 Treatment involves medical resuscitation if hemadymmedially instable, surgical consultation and bowel resection for definition care.27
Juvenile polyps are a common cause of GI bleeding outside the neonatal period. Bleeding is typically painless, recurrent, and small in quantity. Most polyps in children are solitary, benign, and occur within the left colon, often in the rectosigmoid region.19 Diagnosis is made by direct visualization with endoscopy, which also allows for therapeutic excision (Fig. 71-4).
A 0.7-cm pedunculated polyp was identified in the sigmoid colon of a child presenting with painless rectal bleeding. (Used with permission from Dr. Brian Riedel, Pediatric Gastroenterology, West Virginia University School of Medicine.)
Intestinal inflammatory disorders can cause lower GI bleeding. Up to 15% of infants have IgE-mediated milk protein allergic colitis, responsible for up to 20% of rectal bleeding in children less than 1 year old.28 These infants are usually well-appearing but may present with poor weight gain, anemia, metabolic derangements, or failure to thrive. Most infants are treated empirically with exclusion of any known allergens.28 Soy-based foods and formulas should also be eliminated due to 60% cross-reactivity with animal proteins. Even with dietary modification, bloody stools can persist for weeks.29
Inflammatory bowel disease (IBD), ulcerative colitis and Crohn disease, most commonly occurs in adolescents, causing crampy abdominal pain, frequent bloody stools, tenesmus, and weight loss (Fig. 71-5). While ulcerative colitis involves only the colon, Crohn disease can involve any portion of the GI tract. Laboratory evaluation may reveal anemia, thrombocytosis, or an elevated ESR; colonoscopy with biopsy is required for definitive diagnosis.30 Therapy involves anti-inflammatory and immunosuppressive medications, and rarely surgical resection.
Edema, friability, and ulceration of colon seen on endoscopy in a child with ulcerative colitis. (Used with permission from Dr. Brian Riedel, Pediatric Gastroenterology, West Virginia University School of Medicine.)
Henoch–Schönlein Purpura (HSP), an immune-mediated vasculitis which can involve the entire GI tract, can have GI manifestations including abdominal pain, vomiting, and bloody stools. Although bleeding is usually due to mucosal hemorrhage, lesions can act as a lead point for developing intussusception with the potential for bleeding from bowel ischemia. HSP is diagnosed clinically, particularly challenging when GI manifestations precede the pathognomonic purpuric skin changes. Although there is no current consensus on treatment, corticosteroids may ameliorate GI symptoms.31
Colonic lymphonodular hyperplasia from protein allergy or infection can result in asymptomatic, small-volume bleeding. More common in infants and young children, these inflammatory patches present with flecks of blood mixed in the stool of otherwise asymptomatic children. Lymphonodular hyperplasia is diagnosed on colonoscopy and does not require any specific treatment (Fig. 71-6).32
Diffuse lymphonodular hyperplasia is seen in this child undergoing colonoscopy for rectal bleeding. (Used with permission from Dr. Brian Riedel, Pediatric Gastroenterology, West Virginia University School of Medicine.)
Benign lesions of the rectum and anus can cause apparent lower GI bleeding. Anal fissures, the most common cause of rectal bleeding in infants, present with bright red blood external to the stool and typically caused by passing painful, hard stools. Hemorrhoids, resulting in painful defecation with bloody spotting, are uncommon in young children, but can occur after prolonged constipation in adolescents. Diagnosis is made on physical examination, with treatment directed at dietary modifications and stool softeners. Young children with constipation are predisposed to rectal prolapse, which may result in scant rectal bleeding (Fig. 71-7). The prolapsed segment often self-reduces, with the diagnosis made on history alone. If a child presents with rectal prolapse, apply firm constant pressure to reduce, otherwise, surgical consultation is necessary; prescribe stool softeners to minimize recurrence (polyethylene glycol 0.5–1 g/kg BID, max 17 g/day, for up to 8 weeks). Trauma from sexual abuse may also present as rectal bleeding.
Rectal prolapse was seen on examination of this child presenting with rectal pain and bleeding. (Used with permission from Dr. Thomas J. Abramo, Pediatric Emergency Medicine, Vanderbilt University Medical Center.)