Lower gastrointestinal bleeding can occur anywhere from the ligament of Treitz to the anus and varies by age (Table 72–2). Although lower gastrointestinal bleeding is a common complaint, encompassing 0.3% of pediatric emergency department visits, most causes are relatively benign and self-limited.1 The actual bleeding source, however, can occasionally be difficult to identify. Lower gastrointestinal bleeding can present as melena or hematochezia. Melena typically indicates a more proximal source and occurs when blood has been present in the gastrointestinal tract for a prolonged period of time, resulting in breakdown of hemoglobin.13 Small volume hematochezia is typically from the distal colon or anus, although large volume rectal bleeding can result from lesions any place along the gastrointestinal tract if bleeding is brisk. Lower gastrointestinal bleeding can occur in the small intestine, colon, rectum, or anus.
A common cause of lower gastrointestinal bleeding 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.1 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 and close follow-up. Diagnosis is commonly made by stool culture or antigen testing. Many infections in otherwise healthy children do not require treatment, and in some cases, treatment with antimicrobials may worsen the clinical course. Treatment with appropriate antimicrobials is recommended, however, for patients with documented Shigella, Campylobacter, C. difficile, and E. histolytica.14 Antimotility agents should generally be avoided.
Necrotizing enterocolitis (NEC) is a rare but serious cause of lower gastrointestinal bleeding in young infants. Although most often seen in the newborn intensive care unit, occasionally neonates may present to the emergency department. These infants often have a history of prematurity, significant anoxic stress at birth, or cyanotic congenital heart disease.15,16 Infants with NEC typically appear ill, with lethargy, abdominal distension, vomiting, and bloody stools. Abdominal radiographs reveal distended loops of bowel and pneumatosis intestinalis. Treatment involves appropriate resuscitation, bowel rest, broad-spectrum antimicrobials, and early surgical consultation.15
Children with Hirschprung's disease can develop toxic megacolon and present acutely ill with abdominal distension, fever, explosive diarrhea, hematochezia, and abdominal pain. Toxic megacolon can be the presentation of Hirschprung's disease, but can also occur after surgical resection of the aganglionic segment, particularly in children with longer segment disease or Down syndrome.17 Intestinal dilatation with air–fluid levels is often seen on plain abdominal x-ray, often with an intestinal cutoff sign (abrupt cutoff of intestinal distension at the pelvic brim, Fig. 72–3).18 Treatment involves bowel decompression, hydration, and broad-spectrum antibiotics.17
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. (Photo courtesy of Dr. Thomas J. Abramo, Pediatric Emergency Medicine, Vanderbilt University Medical Center.)
Obstructive disorders of the intestine can also lead to lower gastrointestinal bleeding. Although typically small in volume, the bleeding associated with obstruction is typically secondary to tissue ischemia. The most common cause of bleeding from obstruction is intussusception. Intussusception most commonly occurs in children younger than 2 years. These children typically present with intermittent colicky abdominal pain and vomiting, although some children present with only generalized illness and malaise. 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 described as “currant-jelly,” and occurs late in the course, after bowel ischemia has occurred.1 Abdominal radiographs may show a “target sign” or paucity of bowel gas in the right lower quadrant, but may also be normal.15 Ultrasound is a common modality to diagnose intussusception. Air-contrast enema can be both diagnostic and therapeutic for intussusception, but complications such as failure to reduce the intussusception or bowel perforation can occur, and surgical consultation may be warranted.
Volvulus can also present with rectal bleeding from bowel ischemia. It is most common in neonates and typically presents with bilious vomiting, abdominal distension, and feeding problems. Abdominal radiographs may reveal a paucity of gas in the abdomen with a “double bubble sign,” with foci of gas seen in the stomach and duodenum. An upper gastrointestinal contrast study is the diagnostic study of choice. Appropriate 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.1
Otherwise asymptomatic bleeding of the small intestine can be due to lesions such as a Meckel's diverticulum or juvenile polyp. Meckel's diverticulum occurs when the omphalomesenteric duct is incompletely obliterated early in fetal life. Two percent of the population has this 2-in long diverticulum within 2 ft. of the ileocecum.1,19 If the diverticulum contains ectopic gastric mucosa, ulceration and massive bleeding can occur. Patients typically present before age 2 and are well-appearing with painless rectal bleeding. A radionuclide scan with technetium-99 m pertechnate is diagnostic.1 This radioisotope binds preferentially to gastric mucosa. Treatment involves surgical consultation and resection. Meckel's diverticulum can also act as a lead point for intussusception.19 Duplications of the small intestine can also contain ectopic gastric mucosa. Juvenile polyps are a common cause of gastrointestinal bleeding outside the neonatal period. Bleeding is typically painless, recurrent, and small in amount. Most polyps in children are solitary, benign, and occur within the left colon, often in the rectosigmoid region.13 Diagnosis is typically made on endoscopy, which may also allow for excision if the polyp is small (Fig. 72–4).
A 0.7-cm pedunculated polyp was identified in the sigmoid colon of a child presenting with painless rectal bleeding. (Photo courtesy of Dr. Brian Riedel, Pediatric Gastroenterology, Vanderbilt University Medical Center.)
Inflammatory disorders of the intestine are also a common cause of lower gastrointestinal bleeding. Infants most commonly have milk protein allergic colitis. These infants are well-appearing, but present with a history of bloody stools and occasionally vomiting or failure to thrive. Cow milk and soy milk are the most commonly implicated allergens, although in a significant number of infants the allergen is unknown.20 Diagnostic testing is difficult, and most infants are diagnosed clinically and treated empirically by exclusion of any known allergens from the infant's or breast-feeding mother's diet.20 Even with dietary modification, however, bloody stools can persist for weeks.19
Inflammatory bowel disease including ulcerative colitis and Crohn's disease commonly results in rectal bleeding (Fig. 72–5). Most common in adolescents, inflammatory bowel disease often mimics other causes of colitis, causing crampy abdominal pain, frequent bloody stools, tenesmus, and weight loss. While ulcerative colitis typically only involves the colon, Crohn's disease can involve any portion of the gastrointestinal tract. Laboratory evaluation may reveal anemia, thrombocytosis, and elevated ESR. Colonoscopy with biopsy is required for diagnosis in most cases.22 Therapy involves anti-inflammatory and immunosuppressive medication and occasionally surgical intervention.
Edema, friability, and ulceration of colon seen on endoscopy in a child with ulcerative colitis. (Photo courtesy of Dr. Brian Riedel, Pediatric Gastroenterology, Vanderbilt University Medical Center.)
Henoch–Schönlein Purpura (HSP) is a common immune-mediated vasculitis, which can involve the entire gastrointestinal tract. Children with HSP often have gastrointestinal manifestations including abdominal pain, vomiting, and bloody stools or melena. Most commonly, bleeding is due to mucosal hemorrhage, but intussusception is also common among children with HSP. Diagnosis of HSP is made clinically, which can offer a challenge as gastrointestinal manifestations can precede the pathognomonic purpuric skin changes. Although there is no current consensus on treatment, administration of corticosteroids may ameliorate some gastrointestinal symptoms in HSP.23
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 may result in flecks or small amounts of blood mixed in the stool of otherwise asymptomatic children. Lymphonodular hyperplasia is typically diagnosed on colonoscopy and does not require any specific treatment24 (Fig. 72–6).
Diffuse lymphnodular hyperplasia is seen in this child undergoing colonoscopy for rectal bleeding. (Photo courtesy of Dr. Brian Riedel, Pediatric Gastroenterology, Vanderbilt University Medical Center.)
Benign lesions of the rectum and anus can also cause apparent lower gastrointestinal bleeding. The most common cause of rectal bleeding in infants is an anal fissure. These infants typically pass a painful, hard stool with bright red blood seen on the surface of the stool. Hemorrhoids are uncommon in young children but can occur in constipated adolescents. They result in painful defecation, often with the blood on the outside of the stool. Diagnosis is made on physical examination, and treatment involves dietary modifications or medications to soften the stool. Young children with constipation are also predisposed to rectal prolapse, which may result in scant rectal bleeding (Fig. 72–7). The prolapsed segment often self-reduces, and the diagnosis is made on history and physical examination alone. If a child presents with rectal prolapse, firm constant pressure will typically result in reduction, otherwise surgical consultation is necessary. Softening the stool will minimize recurrence. Trauma from sexual abuse may also present as rectal bleeding (see Chapter 145 for more details) (Fig. 72–7).
Rectal prolapse was seen on examination of this child presenting with rectal pain and bleeding. (Photo courtesy of Dr. Thomas J. Abramo, Pediatric Emergency Medicine, Vanderbilt University Medical Center.)