TABLE 23.1 CAUSES OF DIARRHEA Infections Enteral Viruses: rotavirus, caliciviruses (norwalk and sapporo viruses), enteroviruses, adenoviruses, astroviruses Bacteria: Salmonella, Shigella, Yersinia, Campylobacter, pathogenic Escherichia coli, Aeromonas hydrophila, Vibrio spp., Clostridium difficile, tuberculosis Parasites: Giardia lamblia, Entamoeba histolytica, Cryptosporidia Nongastrointestinal (parenteral diarrhea): otitis media, pneumonia, urinary tract infection Dietary disturbances Overfeeding, food allergy, starvation stools Anatomic abnormalities Intussusception, Hirschsprung disease, partial obstruction, appendicitis, blind loop syndrome, intestinal lymphangiectasia, short bowel syndrome Inflammatory bowel disease Ulcerative colitis, Crohn disease Malabsorption or increased secretion Cystic fibrosis, celiac disease, disaccharidase deficiency, acrodermatitis enteropathica, secretory neoplasms Systemic illnesses Immunodeficiency Endocrinopathy: hyperthyroidism, hypoparathyroidism, congenital adrenal hyperplasia Psychogenic disturbances (irritable bowel syndrome) Miscellaneous Antibiotic-induced diarrhea, secondary lactase deficiency, neonatal drug withdrawal, toxins (e.g., organophosphate ingestion), hemolytic uremic syndrome TABLE 23.2 LIFE-THREATENING CAUSES OF DIARRHEA Intussusception Hemolytic uremic syndrome Pseudomembranous colitis Appendicitis Salmonella gastroenteritis (with bacteremia in the neonate or immunocompromised host) Hirschsprung disease (with toxic megacolon) Inflammatory bowel disease (with toxic megacolon) Appendicitis manifests primarily with abdominal pain Common presentation is periumbilical abdominal pain that migrates to the right lower quadrant, followed by anorexia, vomiting, and/or fever Less commonly, appendicitis may cause diarrhea The presumed mechanism for the diarrhea is irritation of the colon by the inflamed appendix Particularly in very young children or among patients of any age who have a perforated appendix and a long duration of illness, the diagnosis of appendicitis as the cause of diarrhea may be delayed because the classic constellation of signs and symptoms is often absent However, the examiner will usually be able to elicit abdominal tenderness greater than would be expected with gastroenteritis Toxic megacolon is a life-threatening condition that can occur as a complication of a number of conditions including inflammatory bowel disease (IBD), Shigella infection, pseudomembranous colitis, and Hirschsprung disease It is characterized by a dilated colon and abdominal distention with abdominal pain and fever that may progress to shock EVALUATION AND DECISION The history and physical examination are paramount in determining if the child with diarrhea has a mild self-limiting illness or a condition that is potentially life threatening For patients with diarrhea, a comprehensive history, including exposure history should be obtained Further, the physician must also identify if the diarrheal illness is acute or chronic as the etiologies can be different In evaluating a child with diarrhea, a rapid assessment is necessary to determine the need for urgent or emergent fluid resuscitation Historical information that should be elicited include detailed questions about the onset of illness, frequency (number of diarrheal stools per day), quantity (smear in the diaper or stool fills and overflows the diaper in infants), and characteristics (e.g., bloody, mucoid, black) of stools, presence of concurrent vomiting, the amount of liquid taken orally, and the frequency or volume of urination (number of wet diaper changes in the infant) A diagnostic approach to the pediatric patient with diarrhea is outlined in Figure 23.1 Inquiry about associated symptoms may be helpful in determining possible causes and need for other acute interventions The presence of vomiting and fever may help determine infectious versus noninfectious causes Vomiting in association with diarrhea is very suggestive of viral gastroenteritis, whereas bilious vomiting in isolation is more concerning for intestinal obstruction Bloody diarrhea points particularly to bacterial enteritis but occasionally occurs with viral infections and may also herald the onset of HUS or pseudomembranous colitis The combination of episodic abdominal pain and blood in the stool characterizes intussusception The presence of abdominal pain should raise the index of suspicion for appendicitis and intussusception A history of ear pain, cough, or dysuria should alert to the possibility of nonintestinal infections as the etiology of the diarrhea A history of family members or close contacts with similar symptoms may indicate a food-borne etiology The use of recreational water facilities such as pools and lakes may indicate a waterborne pathogen Institutionalized children and those recently returning from underdeveloped countries are more likely to harbor bacterial or parasitic pathogens A history of daycare exposure suggests a viral infection whereas recent antibiotic use may suggest antibiotic-associated diarrhea or pseudomembranous colitis Pre-existing conditions in the child may account for the diarrhea or predispose him or her to unusual causes; in particular, the emergency physician should search for a history of gastrointestinal surgery or chronic illnesses, such as ulcerative colitis or regional enteritis Immunodeficiency syndromes, neoplasms, and immunosuppressive therapy all lead to an increased susceptibility to infection A child who presents with chronic diarrhea (more than 14 days) may suggest other etiologies such as IBD, irritable bowel disease, bacterial infections, Hirschsprung disease, human immunodeficiency infection (HIV), and assorted malabsorptive and secretory disorders With the possible exception of bacterial enteritis in a febrile or toxic-appearing patient, such conditions, if uncomplicated, not require a definitive diagnosis emergently, but rather an evaluation over time A complete physical examination is essential for determining the severity of the dehydration in the child with diarrheal illness as well as for determination of potential etiologies for the diarrhea (see Chapters 22 Dehydration and 100 Renal and Electrolyte Emergencies ) Various clinical scales have been developed and validated to determine the degree of dehydration Scales that are commonly used in the acute care setting include the Gorelick scale, the Clinical Dehydration Scale (CDS), and the World Health Organization (WHO) scale See Figure 23.2 for these scales Altered mental status may be seen in children with severe dehydration, hypovolemic shock, and intussusception Pallor and petechiae may denote HUS or malignancy On abdominal examination, the findings of a mass (IBD, intussusception, malignancy) or evidence of obstruction (abdominal distention, pain, and paucity of bowel sounds) is important A rectal examination should be performed in the child who has chronic diarrhea With overflow stools secondary to prolonged constipation, the rectal ampulla often contains a large amount of hard stool, but it is usually empty in the patient with Hirschsprung disease Routine diagnostic testing is not necessary in pediatric patients with suspected self-limiting diarrheal disease Patients with fever, bloody diarrhea, mucoid stools, severe abdominal pain, and/or signs of sepsis should have stool samples evaluated for bacterial and other pathogens Blood cultures are indicated for ill or toxic-appearing patients of any age with diarrhea, children under months, immunocompromised hosts, and those being evaluated for fever of unknown origin who have traveled to or had contact with travelers from enteric fever endemic areas If a history of significant stool output accompanied by poor oral intake is obtained, bedside point of care glucose check should be performed to evaluate for possible hypoglycemia, especially in infants and toddlers Electrolytes, BUN, and creatinine should be obtained only if the history and/or physical examination are concerning for potential electrolyte abnormalities or impaired renal function Plain abdominal films should be performed in patients with suspected gastrointestinal obstruction but are frequently normal in children with intussusception and gastroenteritis Because of its high diagnostic sensitivity and lack of ionizing radiation, ultrasound (US) has replaced contrast enema as the diagnostic test of choice in children with suspected intussusception US may also be helpful in the diagnosis of the patient with appendicitis When HUS is suspected, a complete blood count, renal function studies including serum creatinine, urinalysis, coagulation studies, and peripheral smear should be performed The peripheral blood smear, in addition to reduced numbers of platelets, may show evidence of intravascular hemolysis, including helmet cells ... or volume of urination (number of wet diaper changes in the infant) A diagnostic approach to the pediatric patient with diarrhea is outlined in Figure 23.1 Inquiry about associated symptoms may... child may account for the diarrhea or predispose him or her to unusual causes; in particular, the emergency physician should search for a history of gastrointestinal surgery or chronic illnesses,... usually empty in the patient with Hirschsprung disease Routine diagnostic testing is not necessary in pediatric patients with suspected self-limiting diarrheal disease Patients with fever, bloody diarrhea,