Symptom-Based Diagnosis in Pediatrics (CHOP Morning Report) 1st Ed.




Diarrhea is one of the most common conditions for which patients seek medical care. It is a condition that continues to be associated with significant morbidity and mortality worldwide, despite medical advances. It is characterized by an increase in the frequency, volume, or liquid content of stool as compared to any given individual’s usual pattern.

Diarrhea may also be further characterized by the duration of the symptoms, with acute episodes of diarrhea generally resolving within 2 weeks, while chronic diarrhea generally lasts longer than 2 weeks. Another important distinction in the type of diarrhea is based on whether it is secretory or osmotic in nature. Agents that disrupt the normal absorption of intestinal luminal fluid at the cellular level generally cause a profuse and voluminous secretory diarrhea that continues regardless of the patient’s oral intake. Osmotic diarrhea, however, is the result of poorly absorbed substances that draw fluid into the intestinal lumen. This type of diarrhea tends to improve with fasting on the part of the patient.

The most common causes of diarrhea are infectious, with viral etiologies occurring more frequently than bacterial. The differential diagnosis of diarrhea, however, is quite extensive and includes some rare causes. Many cases of diarrhea occur in children who are otherwise well appearing, while some cases of diarrhea present in children who are ill appearing, due to either poor nutrition, hydration, or other systemic reasons.


There are myriad causes of diarrhea that can be stratified by age (Table 17-1) or diagnostic category (Table 17-2).

TABLE 17-1. Causes of diarrhea by age.


TABLE 17-2. Causes of diarrhea by diagnostic category.



A thorough history can provide clues to facilitate an accurate diagnosis in the child who presents with diarrhea. Consideration of the age and appearance of the patient, the length and course of the illness, and associated clinical features provides a useful framework for creating a differential diagnosis. The following questions may help provide clues to the diagnosis:

• How long has the diarrhea lasted?

—Diarrhea that has lasted less than 2 weeks is acute diarrhea, rather than chronic. Acute diarrhea is more likely to be infectious (viral or bacterial) in etiology. Chronic diarrhea raises the concern over other diagnoses such as malabsorptive conditions (cystic fibrosis, celiac disease), although infectious (parasitic) and postinfectious (postinfectious carbohydrate malabsorption) causes are still possible.

• Is there any blood or mucus in the stool?

—In the acute setting, blood or mucus in the stool increases the possibility of an enteroinvasive agent (enteroinvasive Escherichia coliSalmonella spp. or Shigella spp.). In the chronic setting, inflammatory bowel disease should be considered. In a systemically ill-appearing child, hemolytic uremic syndrome must be considered.

• Is there abdominal pain or cramping? Tenesmus?

—Acute infectious gastroenteritis can present with abdominal cramping, while a chronic history of cramping or tenesmus raises the concern for inflammatory bowel disease.

• Is there any vomiting?

—Vomiting may be associated with acute infectious gastroenteritis. However, if bilious vomiting is noted, especially in a neonate or an infant, an anatomic condition (malrotation, incarcerated hernia) must be considered.

• Is there a fever?

—Presence of a fever acutely may indicate either an enteroinvasive infectious agent or systemic illness (pneumonia) with an associated nonspecific diarrhea. In a toxic-appearing child, sepsis and toxic shock syndrome must be considered. In a patient with a chronic history of diarrhea with acute exacerbations associated with fever, inflammatory bowel disease is a distinct possibility.

• Does the patient appear systemically ill?

—In acute diarrhea, a systemically ill-appearing child should raise the concern for sepsis (Salmonella spp., E. coli, especially in a neonate or infant). If oliguria is also present, hemolytic uremic syndrome must be considered, in addition to simple dehydration associated with diarrheal losses. In patients who have a history of chronic diarrhea and failure to thrive, superimposed episodes of acute diarrhea can make them appear systemically ill, as in cases of inflammatory bowel disease, celiac disease, or cystic fibrosis.

• Is there failure to thrive?

—A chronic history of diarrhea associated with failure to thrive raises the concern for malabsorptive conditions such as cystic fibrosis and celiac disease. Neuroendocrine tumors that cause a secretory diarrhea may present with significant weight loss. Inflammatory bowel disease also commonly presents with linear growth arrest in addition to poor weight gain.

• Are there ill contacts with diarrhea?

—Close contacts with similar symptoms may indicate an outbreak with a common source of contamination (e.g., daycare, family reunion, restaurant), whether toxin-associated food poisoning, or fecal-oral contamination.

• Is there any unusual food exposure?

—In particular, undercooked foods, specifically beef, are of concern as a source for E. coli O157:H7 resulting in hemolytic uremic syndrome (HUS). Improperly stored food is another potential source for food poisoning. New foods may not be tolerated well and be the source of transient diarrhea or may cause bloody diarrhea, as in the case of milkprotein allergy in infants.

• Any recent history of travel?

—Foreign travel increases the concern over travelers’ diarrhea, often due to unfamiliar strains of E. coli, or unusual organisms, such as Entamoeba histolytica, as a cause of chronic diarrhea. Other parasites such as Giardia lambliaand agents such as hepatitis A may also be acquired during travel.

• What is the water source?

—Untreated or contaminated water sources can harbor Giardia lamblia or Cryptosporidium. Cases of E. coli O157:H7 transmission have also been known to occur with exposure in water sources such as swimming pools or lakes.

• Are there any pets? Any exposure to animals?

—Pets such as lizards, turtles, and iguanas may harbor Salmonella, which can then cause diarrhea in children who play with them. Farm animals and petting zoos are also potential sources for E. coli O157:H7 and epidemic cases of hemolytic uremic syndrome.

• Is there a history of recent antibiotic use?

—Antibiotic-associated diarrhea, including Clostridium difficile colitis, may occur.

• Is there any significant medical history?

—Failure to thrive is of particular concern with either superimposed acute or chronic diarrhea. Former premature infants who had surgical necrotizing enterocolitis may have subsequent chronic diarrhea due to short bowel syndrome. Other conditions may also have diarrhea associated (human immunodeficiency virus infection and other immune compromising conditions) as well as endocrinologic disorders (e.g., hyperthyroidism).

• Is there a significant family history?

—Patients with inflammatory bowel disease may present with family members with similar symptoms. Cystic fibrosis and celiac disease have traditionally been associated with Northern European ancestry, although patients of other ethnicities can also carry these diagnoses.

• Is the diarrhea worse with oral intake? Is it improved with fasting?

—This question will help to differentiate osmotic diarrhea, which characterizes most cases of diarrhea, from secretory diarrhea, which is much less common and often is associated with otherwise occult oncologic conditions.

• Is there a rash?

—A petechial, purpuric rash would be indicative of Henoch-Schönlein purpura, although, in an ill-appearing child, sepsis would also have to be considered. Other rashes, such as dermatitis herpetiformis, can be seen in chronic conditions, such as celiac disease. Rashes may also develop due to nutritional deficiencies.

• Is the weight loss intentional?

—Teenagers who are overly concerned with body image may be using laxatives to lose weight.