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.

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