Diarrhea

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Chapter 11 Diarrhea

Linda D. Arnold, MD

1 What is diarrhea?

Diarrhea is defined as a decrease in the consistency, or an increase in the frequency, of stool. Marked variations of “normal” number, volume, and consistency of stools exist between individuals. Breastfed babies, for example, may stool more than seven times a day. An increase in stool quantity, or a frequency of more than 10 stools/day, constitutes diarrhea in infants. By age 3, stool output reaches adult norms of 100 gm/day; a high-fiber diet increases the volume. Stool output of more than 200 gm/day meets the definition of diarrhea.

Diarrhea is caused by a disturbance of the mechanisms that regulate intestinal fluid and electrolyte transport. Nonspecific inflammation, epithelial invasion by micro-organisms, fluid or carbohydrate excess, and pharmacologic agents have all been implicated.

2 How big a problem is diarrhea?

In the United States, acute gastroenteritis leads to more than 1.5 million office visits and 200,000 hospitalizations each year for children under the age of 5. It accounts for approximately 10% of all hospital admissions for this age group. Direct costs in this country have been estimated to be over $2 billion per year. Hundreds of children in the United States die each year because of resulting dehydration or systemic illness. Morbidity and mortality are greatest in infants and malnourished or immunocompromised children. Risk of dehydration is further increased in minorities, children of young single mothers, and those with a history of prematurity.

King CK, Glass R, Bresee JS, et al: Managing acute gastroenteritis among children: Oral rehydration, maintenance, and nutritional therapy. MMWR Morb Mortal Wkly Rep 52:1–16, 2003.

3 What role does duration of symptoms play in determining the etiology of diarrhea?

Diarrhea of less than 2-week duration is classified as “acute” and, in the majority of cases, results from enteric infection. Extraintestinal infections, such as urinary tract infections, otitis media, and appendicitis, can also cause diarrhea and should be ruled out. Acute diarrhea may also be the result of food-borne toxins, or the initial manifestation of milk or soy protein intolerance.

4 What are common causes of chronic diarrhea?

image Chronic diarrhea in infants may be postinfectious, the result of protein intolerance or malnutrition, subsequent to metabolic disorders such as cystic fibrosis or enzyme and transport defects, or secondary to anatomic anomalies.

image In older infants and toddlers, chronic, nonspecific “toddler’s diarrhea”; protein intolerance; and postinfectious diarrhea are all common. Children in this age group frequently present with other etiologies, including giardiasis, celiac sprue, sucrase-isomaltase deficiency, and Hirschsprung’s enterocolitis.

image In school-aged children and adolescents, consider giardiasis, celiac disease, lactose intolerance, irritable bowel, and inflammatory bowel disease. Teens with chronic diarrhea should be questioned about laxative use/abuse.

5 What clues can the history provide?

image Viral pathogens tend to injure the proximal small intestine. Onset of illness is generally abrupt and duration limited. These patients are more likely to be afebrile and to present with both emesis and diarrhea. Associated respiratory symptoms or rash are often seen.

image Bacterial pathogens produce colonic inflammation, with bloody or mucoid stools, and cramping abdominal pain. Fever and tenesmus may be prominent features. Bacterial toxins may produce a watery stool.

image Food poisoning is characterized by abrupt onset of vomiting after a meal, followed by diarrhea.

image Foul-smelling stools suggest malabsorption.

image An increase in flatus may be seen with Giardia infection or lactose intolerance.

image Irritable bowel syndrome is characterized by cramping, as well as frequent, small-volume, liquid stools alternating with constipation; physical and emotional stress exacerbate the condition.

6 What specific questions should I ask parents of a child with diarrhea?

Question parents about recent travel, pets, and possible exposure to untreated drinking water or fecally contaminated recreational waters. Ask detailed questions about duration of symptoms, oral intake, frequency of wet diapers, and weight loss to assess for degree of dehydration.

7 What should I look for on physical examination?

Assess the child’s hydration status carefully. Heart rate, quality of mucous membranes, capillary refill and perfusion, sunken eyes or fontanelle, and activity level all offer important clues. Plot the weight and weight/height ratios, as this may point to an underlying chronic disorder. Children with uncomplicated gastroenteritis tend to have mild diffuse abdominal tenderness and active bowel sounds. Localized tenderness, rebound tenderness, and absent or high-pitched bowel sounds indicate a possible surgical process or bowel obstruction. Palpation of a mass or a discrete loop of bowel suggests inflammatory bowel disease (IBD), intussusception, or constipation. Increased anal tone and explosive stools should raise concerns of Hirschsprung’s enterocolitis, while perianal tags, fissures, or abscesses are characteristic of IBD. A “doughy” feel to the skin may be a hallmark of hypernatremic dehydration. Diarrhea associated with pallor may suggest hemolytic uremic syndrome. Children with protuberant abdomens and wasting of the buttocks and extremities should be evaluated for giardiasis, celiac sprue, and cystic fibrosis.

8 When is diarrhea dangerous?

Emergency intervention is required for the child with moderate-to-severe dehydration or when a surgical etiology is suspected. Children with hypernatremic dehydration should be managed carefully, as they may develop cerebral edema if rehydration occurs too rapidly. Hirschsprung’s enterocolitis has up to a 50% mortality rate: it should be treated promptly with decompression via a rectal tube, pending definitive treatment. Appendicitis, often misdiagnosed in children, may present with diarrhea secondary to cecal inflammation. When symptoms of abdominal pain, vomiting, and lethargy accompany the passage of “bloody diarrhea,” intussusception should be high on the list of conditions in the differential diagnosis. Unexplained diarrhea that doesn’t fit a particular pattern should raise the possibility of Munchausen syndrome by proxy in an infant or younger child and of laxative abuse in the adolescent.

9 What is the role of daycare in childhood diarrheal disease?

While the average child under age 3 years has two to three episodes of diarrhea per year, the rate doubles for children in daycare. Children in this setting are at increased risk for both fecal–oral and fomite transmission of enteric pathogens. Daycare attendance has been implicated in outbreaks of rotavirus, astrovirus, shigella, campylobacter, giardia, and cryptosporidium.

10 Name the common infectious causes of diarrhea.

image Viral: Rotavirus, Norwalk-like virus, enteric adenovirus, astrovirus, calicivirus

image Bacterial: Salmonella, Shigella, Campylobacter, or Yersinia spp., Escherichia coli, Clostridium difficile

image Parasitic: Giardia sp., Cryptosporidium sp., Entamoeba histolytica, Strongyloides sp., Microsporidium sp.

11 What conditions may be mistaken for infectious diarrhea?

image Chronic nonspecific (toddler’s) diarrhea

image Sorbitol-induced diarrhea

image Milk protein allergy

image Lactose intolerance

image Munchausen syndrome by proxy

12 When is diarrhea not diarrhea?

Children with severe constipation can develop overflow incontinence. Encopresis involves frequent soiling with liquid stool, which leaks around a solid fecal mass. Encopretics are unaware that they are soiling because of decreased rectal tone and sensation. Physical examination often reveals stool-filled intestinal loops and impacted stool on rectal examination, while a history of “streaking” of the underpants is frequently obtained.

13 Do the color and appearance of the stool matter?

Visible blood or mucus in the stool suggests an inflammatory etiology. Aside from the presence of blood, the color of the stool is generally not important. Bulky stools are seen in fat malabsorption, while watery explosive stools may indicate carbohydrate malabsorption. Parents may describe the appearance of undigested food particles in the frequent stools associated with toddler’s diarrhea. These are, in fact, undigested cellulose particles that are not disintegrated in the colon.

14 Is the odor of the stool important?

Carbohydrate malabsorption results in foul, watery stools that have a vinegar-like odor. The stools of a patient with fat malabsorption are bulky and foul smelling. Consider celiac disease, cystic fibrosis, pancreatic insufficiency, and bile salt malabsorption in the presence of steatorrhea. Pleasant-smelling stools simply do not exist.

15 What foods can mimic bloody stool?

Children who have ingested fruit juices, gelatin, popsicles, Kool-Aid beverages, red candies, tomatoes, beets, or cranberries may have red stools. Tarry-looking stools result from the consumption of bismuth-containing antidiarrheal products, iron, black licorice, spinach, blueberries, purple grapes, chocolate, or grape juice. Nonbloody stools may test positive on fecal occult blood tests in a child who has eaten red meat, cherries, tomato skin, or iron supplements.

16 Are there seasonal variations in the causative agents of infectious diarrhea?

Rotavirus, the most common cause of infectious diarrhea in infants and children, is more common during winter months in temperate climates. No seasonal variation is seen in tropical climates. Bacterial pathogens are more likely in the summer and early fall months. Undercooked meats and poorly refrigerated side dishes at picnics and cookouts are frequently implicated. Fecal contamination of recreational waters and consumption of untreated fresh water by campers may increase exposure to parasites during warmer months.

17 Should clear liquids be given by mouth until diarrhea resolves?

Formula provides superior nutrition to clear liquids and should be offered throughout the course of an uncomplicated illness, if tolerated. When clear liquids are used, families should be instructed to avoid apple juice, soda, or sports beverages. Their hypertonicity and high carbohydrate load can cause diarrhea to worsen. Use of one of the commercially available glucose electrolyte–containing solutions is preferable. Nursing mothers should not be instructed to stop breastfeeding infants or toddlers with diarrhea.

18 Which children with diarrhea require IV hydration?

Oral rehydration therapy (ORT) with an appropriate oral rehydration solution (ORS) is recommended for all children with uncomplicated gastroenteritis with mild-to-moderate dehydration. Though time consuming, it has been shown to be as effective as IV hydration in this group when caregivers are trained and motivated. For children with complicated illness, moderate-to-severe dehydration, shock, persistent vomiting, or mental status changes, IV hydration will be required. Personnel or caregiver limitations may lead to the need for IV hydration, in settings when ORT would otherwise be appropriate.

American Academy of Pediatrics, Provisional Committee on Quality Improvement, Subcommittee on Acute Gastroenteritis: Practice parameter: The management of acute gastroenteritis in young children. Pediatrics 97:424–435, 1996.

KEY POINTS: MANAGING FLUIDS AND NUTRITION

1 Use of special or dilute formulas is generally not necessary.

2 Mothers should be encouraged to continue breastfeeding.

3 Oral rehydration with hypotonic glucose-electrolyte solutions is the therapy of choice for children with mild-to-moderate dehydration.

4 IV fluids are indicated in cases of moderate-to-severe dehydration or when oral fluids are not tolerated.

5 Rapid return to age-appropriate feeding patterns is indicated once children are rehydrated.

19 Should children with diarrhea avoid milk products?

A lactose-free diet is often recommended during recovery from gastroenteritis but is required only in the face of severe illness or malnutrition. Patients with severe enteritis may have damage to the brush-border membrane of the small intestine, with resulting temporary decreases in the levels of enzymes, such as lactase. Despite this, the majority of infants and children show no clinical signs of subsequent carbohydrate malabsorption when fed full-strength milk or formula. For those infants with persistent watery and explosive diarrhea, a disaccharide-free formula such as Prosobee or Isomil-DF may be useful until the gut recovers. Older children with these symptoms may benefit from avoiding lactose-containing products for a couple of weeks.

20 What is the BRAT diet? Should children with diarrhea adhere to it?

Bananas, rice, applesauce, and toast. Children with gastroenteritis tolerate these foods well, though limiting the diet in this way restricts calories, protein, and fat. The American Academy of Pediatrics recommends reinstituting a regular, age-appropriate diet with full-strength milk as soon as possible.

American Academy of Pediatrics, Provisional Committee on Quality Improvement, Subcommittee on Acute Gastroenteritis: Practice parameter: The management of acute gastroenteritis in young children. Pediatrics 97:424–435, 1996.

21 What complications of infectious diarrhea should I be concerned about?

Both Shigella sp. and E. coli can cause seizures via high fever or toxin elaboration. Salmonella sp. produces bacteremia in approximately 6% of those infected; salmonella bacteremia rates of 11–45% have been reported in infants and neonates. Immunocompromised patients and those with hematologic disorders are at increased risk for developing salmonella osteomyelitis. Giardial infection, as do celiac sprue and IBD, often presents with failure to thrive. C. difficile overgrowth and cytotoxin release may lead to life-threatening pseudomembranous colitis. The cytotoxins elaborated by E. coli O157:H7 induce diffuse endothelial injury, which causes both hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. Ten percent of patients with E. coli O157:H7 infection develop one or both of these sequelae.

22 Should children with diarrhea be treated with antimotility agents?

Pharmacologic antimotility agents are generally not recommended for use in children because of limited testing and potential side effects. Bismuth-containing compounds are moderately effective in shortening the duration of acute diarrhea. They are generally safe, although salicylate absorption may occur, and bismuth encephalopathy has been reported in patients with renal insufficiency. Notably, the black stools that result are often confused with melena.

Opiates, such as Lomotil, and synthetic opiates, such as Imodium, can cause central nervous system–induced sedation and respiratory depression. Additional complications include gastrointestinal ileus with consequent vomiting, abdominal distention, and worsening diarrhea. Gut stasis following use of these agents may lead to invasion of the bowel wall by infectious organisms, leading to worsening infection and prolonged carriage and excretion of pathogenic bacteria. Both should be avoided in infants and young children, and used with caution in older children. Especially avoid Lomotil because it contains atropine. Dysentery is an absolute contraindication to the use of these medications.

KEY POINTS: ACUTE GASTROENTERITIS

1 The majority of cases of acute gastroenteritis are self-limited and require no specific therapy.

2 Morbidity and death due to diarrheal diseases in children result mostly from dehydration.

3 Infants and malnourished children have the greatest risk of sequelae from diarrheal illness.

4 Use of antidiarrheal agents is not routinely recommended for children.

5 Proper handwashing is extremely effective in preventing transmission of infectious agents.

23 When are antibiotics indicated?

image Treat Salmonella gastroenteritis in all infants under 3 months; in bacteremic children younger than 1 year of age; and in children who are immunocompromised or asplenic or appear toxic. In older children, Salmonella gastroenteritis is self-limited; no clinical improvement in fever, duration, or severity occurs after antibiotic therapy (which may, in fact, prolong the carrier state).

image Antibiotic resistance to Shigella sp. is a major problem. Therapy is recommended for the severely ill and for children with persistent symptoms. Consider treating children in daycare, as shedding is stopped within 1–2 days, reducing person-to-person transmission.

image The same is true of Campylobacter enteritis. Disease is mild and self-limited, but shedding may occur for up to 7 weeks without antibiotic therapy.

image Yersinia sp. requires treatment only with severe disease, bacteremia, or underlying illness.

image Antimicrobials may be administered to decrease the duration and severity of symptoms in enterotoxigenic E. coli (traveler’s diarrhea) infections. Most experts recommend against treating children with Shiga toxin-producing E. coli (STEC) with antimicrobials because the risks and benefits of treatment are not known.

image Mild infections with C. difficile improve when antibiotics are stopped. Severe C. difficile colitis should be treated with oral vancomycin or metronidazole.

image Cryptosporidium parvum and Giardia sp. can both be treated with a 3-day course of nitazoxanide; Giardia sp. also responds to furazolidone and metronidazole. Neither food poisoning nor viral infections require antibiotics.

Red Book

www.aapredbook.aappublications.org

24 When should patients with diarrhea be referred to a specialist?

Infants or children with severe or progressive dehydration should be referred to acute care facilities for rehydration and monitoring. Referral is likewise appropriate for a patient who appears toxic or has bloody stools. When a child has a localizing examination or peritoneal signs, a surgical consultation is indicated. Patients with chronic disease or growth failure should be seen by a gastroenterologist.

25 When is testing indicated in children with diarrhea?

Children with chronic diarrhea or evidence of a noninfectious cause for their diarrhea should be screened, if indicated, for conditions such as IBD, celiac disease, or carbohydrate intolerance. Giardia antigen testing, or ova and parasite samples, should be performed in children with chronic diarrhea and failure to thrive. The use of clinical and historical criteria (fever, visible blood or mucus, absence of vomiting, and stool frequency), combined with selective application of screening tests or stool cultures, offers a cost-effective means of identifying patients with bacterial pathogens. A higher index of suspicion is required for infants, as sequelae are more common. During the winter months, rotavirus stool antigen tests may be useful for infection control purposes.

26 What is the best way to prevent diarrheal disease in children?

Multiple studies in both developed and developing countries, set in homes and institutions, have concluded that frequent handwashing is very effective in decreasing the frequency of diarrheal illness in children. When caregivers wash their hands with plain or antibacterial soap after defecating or changing diapers, and before preparing food, eating, and feeding children, the incidence of diarrhea decreases markedly. Likewise, studies in daycare centers show up to 50% decreases in episodes of diarrhea following training and education of children and child care providers.

Roberts L, Jorm L, Patel M, et al: Effect of infection control measures on the frequency of diarrheal episodes in child care: A randomized, controlled trial. Pediatrics 105:743–746, 2000.

27 What new therapies look promising in terms of managing the symptoms of diarrheal disease?

Probiotics such as Lactobacillus GG have gained a lot of attention for their potential role in limiting the symptoms of diarrheal disease. Several studies in children have demonstrated reduced duration of diarrhea when probiotics are used in the setting of acute viral diarrhea (particularly that caused by rotavirus), recurrent C. difficile diarrhea, and diarrhea related to IBD. Both inpatient and outpatient populations have been studied, and the probiotics have been successful when administered alone or when added to OLS.

Guandalini S, Pensabene L, Zikri MA, et al: Lactobacillus GG administered in oral rehydration solution to children with acute diarrhea: A multicenter European trial. J Pediatr Gastroenterol Nutr 30:54–60, 2000.

Rosenfeldt V, Michaelsen KF, Jakobsen M, et al: Effect of probiotic Lactobacillus strains on acute diarrhea in a cohort of nonhospitalized children attending day-care centers. Pediatr Infect Dis J 21:417–419, 2002.

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