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Emergency And Acute Medicine – Diarrhea, Pediatric
Rajender Gattu • Richard Lichenstein
Basics
Description Pediatric diarrhea is one of the most common emergency department complaints, second only to respiratory infections. It is a leading cause of childhood illness and mortality worldwide. Acute infectious enteritis presents with vomiting and diarrhea, most often in children under 5 years of age, who typically experience about two episodes annually. Diarrhea is defined as an acute change in normal bowel habits with increased stool frequency or volume lasting less than 7 days; three or more loose or watery stools per day meet the World Health Organization definition. Diarrhea persisting longer than 2 weeks is considered chronic.
Etiology
Acute enteritis
Infectious causes predominate. Viruses account for 70–80% of cases, most commonly rotavirus, followed by enteric adenovirus and norovirus, particularly in foodborne outbreaks. Bacterial causes account for 10–20% and include Escherichia coli, Salmonella, Shigella, Campylobacter, Yersinia, Vibrio, Clostridioides difficile, and Aeromonas. Parasitic causes represent about 5% and include Giardia lamblia and Cryptosporidium, often waterborne.
Noninfectious causes include postinfectious diarrhea, food allergy or intolerance (cow’s milk protein, soy protein, lactose intolerance), methylxanthines, chemotherapy- or radiation-induced injury, drug-induced diarrhea from antibiotics, laxatives, or antacids, ingestion of heavy metals or toxic plants, vitamin deficiencies (niacin, folate), vitamin excess (vitamin C), and diarrhea associated with other infections such as otitis media, urinary tract infection, pneumonia, meningitis, or appendicitis.
Chronic diarrhea
Dietary excess of sorbitol or fructose, enteric infections in immunocompromised hosts, malnutrition, endocrine disorders such as thyrotoxicosis or pheochromocytoma, inflammatory bowel disease, malabsorption syndromes including cystic fibrosis and celiac disease, and irritable bowel syndrome.
Diagnosis
Signs And Symptoms Frequent loose stools that may be watery, bloody, or mucoid, with possible abdominal pain, fever, anorexia, and tenesmus. Dehydration severity reflects total body water loss and is classified as mild (<5%), moderate (5-10%), or severe (>15%). Severe dehydration is associated with altered mental status, poor muscle tone, dry mucous membranes, decreased skin turgor, depressed fontanelle, hypotension, tachycardia, prolonged capillary refill, decreased urine output, sunken eyes, absent tears, and intense thirst.
History Focus on onset, duration, stool characteristics, urine output, feeding, recent antibiotic use, travel, possible ingestions, immunodeficiency, and underlying intestinal disease.
Physical exam Key findings include abnormal respiratory pattern, decreased skin turgor, and prolonged capillary refill, which together are the most reliable indicators of dehydration.
Essential Workup Most children with acute diarrhea require no laboratory testing. Evaluation is indicated for high fever, systemic illness, bloody diarrhea, symptoms lasting more than 2 weeks, tenesmus, or dehydration beyond mild severity requiring parenteral therapy.
Diagnosis Tests And Interpretation
Lab CBC, blood culture, urinalysis, and urine culture if systemic infection is suspected. Serum electrolytes, BUN, creatinine, and bicarbonate are useful in children requiring IV fluids; low bicarbonate is a sensitive marker of moderate dehydration. Stool pH <5.5 or positive reducing substances suggest lactose intolerance. stool microscopy showing>5 fecal leukocytes per high-power field suggests invasive bacterial infection. Stool cultures are reserved for cases with bloody stools or high likelihood of bacterial pathogens.
Imaging Generally not indicated; abdominal radiography or ultrasound may be useful if intussusception, appendicitis, or ileus is suspected.
Differential Diagnosis Postinfectious diarrhea, milk allergy, malrotation with volvulus, inflammatory bowel disease, intussusception, malabsorption syndromes, extraintestinal infections, and medication-induced diarrhea.
Treatment
Initial stabilization and therapy Severely dehydrated children in shock require IV or intraosseous access with 20 mL/kg of 0.9% normal saline; administer dextrose if hypoglycemic. Pulse oximetry and airway support are used as needed.
Emergency department treatment and procedures Mild to moderate dehydration is treated with oral rehydration therapy at 50–100 mL/kg over 4 hours, with additional 10 mL/kg for each stool. Oral rehydration solutions should be low osmolarity with appropriate glucose and sodium content. Moderate to severe dehydration requires IV fluids to replace maintenance and deficit needs. Antibiotics are reserved for defined invasive or severe infections or high-risk patients. Antidiarrheal agents are not recommended. Probiotics such as Lactobacillus GG may reduce duration of illness. Age-appropriate feeding should continue during rehydration, emphasizing complex carbohydrates, lean proteins, fruits, vegetables, yogurt, and avoidance of fatty or high-sugar foods.
Medication Antibiotic selection depends on identified pathogens and includes agents such as TMP-SMX, erythromycin, metronidazole, vancomycin, ceftriaxone, or doxycycline when indicated. Zinc supplementation is recommended for young children.
Follow-Up Disposition
Admission criteria Surgical abdomen, inability to tolerate oral fluids, dehydration ≥10%, toxic appearance, or suspected complicated bacterial enteritis.
Discharge criteria Clinical improvement, adequate hydration, and caregivers capable of providing oral rehydration and recognizing dehydration signs.
Issues for referral Immunocompromised children, seizure-associated illness, or underlying bowel disease.
Follow-Up Recommendations Uncomplicated diarrhea usually requires no routine follow-up. Neonates and high-risk children require close outpatient reassessment.
Pearls And Pitfalls History and physical examination are key to distinguishing benign diarrhea from serious disease. Most children do not need extensive laboratory testing. Antibiotics and antidiarrheal agents have limited roles. Always consider alternative diagnoses such as appendicitis, intussusception, urinary tract infection, and sepsis.
Rajender Gattu • Richard Lichenstein
Basics
Description Pediatric diarrhea is one of the most common emergency department complaints, second only to respiratory infections. It is a leading cause of childhood illness and mortality worldwide. Acute infectious enteritis presents with vomiting and diarrhea, most often in children under 5 years of age, who typically experience about two episodes annually. Diarrhea is defined as an acute change in normal bowel habits with increased stool frequency or volume lasting less than 7 days; three or more loose or watery stools per day meet the World Health Organization definition. Diarrhea persisting longer than 2 weeks is considered chronic.
Etiology
Acute enteritis
Infectious causes predominate. Viruses account for 70–80% of cases, most commonly rotavirus, followed by enteric adenovirus and norovirus, particularly in foodborne outbreaks. Bacterial causes account for 10–20% and include Escherichia coli, Salmonella, Shigella, Campylobacter, Yersinia, Vibrio, Clostridioides difficile, and Aeromonas. Parasitic causes represent about 5% and include Giardia lamblia and Cryptosporidium, often waterborne.
Noninfectious causes include postinfectious diarrhea, food allergy or intolerance (cow’s milk protein, soy protein, lactose intolerance), methylxanthines, chemotherapy- or radiation-induced injury, drug-induced diarrhea from antibiotics, laxatives, or antacids, ingestion of heavy metals or toxic plants, vitamin deficiencies (niacin, folate), vitamin excess (vitamin C), and diarrhea associated with other infections such as otitis media, urinary tract infection, pneumonia, meningitis, or appendicitis.
Chronic diarrhea
Dietary excess of sorbitol or fructose, enteric infections in immunocompromised hosts, malnutrition, endocrine disorders such as thyrotoxicosis or pheochromocytoma, inflammatory bowel disease, malabsorption syndromes including cystic fibrosis and celiac disease, and irritable bowel syndrome.
Diagnosis
Signs And Symptoms Frequent loose stools that may be watery, bloody, or mucoid, with possible abdominal pain, fever, anorexia, and tenesmus. Dehydration severity reflects total body water loss and is classified as mild (<5%), moderate (5-10%), or severe (>15%). Severe dehydration is associated with altered mental status, poor muscle tone, dry mucous membranes, decreased skin turgor, depressed fontanelle, hypotension, tachycardia, prolonged capillary refill, decreased urine output, sunken eyes, absent tears, and intense thirst.
History Focus on onset, duration, stool characteristics, urine output, feeding, recent antibiotic use, travel, possible ingestions, immunodeficiency, and underlying intestinal disease.
Physical exam Key findings include abnormal respiratory pattern, decreased skin turgor, and prolonged capillary refill, which together are the most reliable indicators of dehydration.
Essential Workup Most children with acute diarrhea require no laboratory testing. Evaluation is indicated for high fever, systemic illness, bloody diarrhea, symptoms lasting more than 2 weeks, tenesmus, or dehydration beyond mild severity requiring parenteral therapy.
Diagnosis Tests And Interpretation
Lab CBC, blood culture, urinalysis, and urine culture if systemic infection is suspected. Serum electrolytes, BUN, creatinine, and bicarbonate are useful in children requiring IV fluids; low bicarbonate is a sensitive marker of moderate dehydration. Stool pH <5.5 or positive reducing substances suggest lactose intolerance. stool microscopy showing>5 fecal leukocytes per high-power field suggests invasive bacterial infection. Stool cultures are reserved for cases with bloody stools or high likelihood of bacterial pathogens.
Imaging Generally not indicated; abdominal radiography or ultrasound may be useful if intussusception, appendicitis, or ileus is suspected.
Differential Diagnosis Postinfectious diarrhea, milk allergy, malrotation with volvulus, inflammatory bowel disease, intussusception, malabsorption syndromes, extraintestinal infections, and medication-induced diarrhea.
Treatment
Initial stabilization and therapy Severely dehydrated children in shock require IV or intraosseous access with 20 mL/kg of 0.9% normal saline; administer dextrose if hypoglycemic. Pulse oximetry and airway support are used as needed.
Emergency department treatment and procedures Mild to moderate dehydration is treated with oral rehydration therapy at 50–100 mL/kg over 4 hours, with additional 10 mL/kg for each stool. Oral rehydration solutions should be low osmolarity with appropriate glucose and sodium content. Moderate to severe dehydration requires IV fluids to replace maintenance and deficit needs. Antibiotics are reserved for defined invasive or severe infections or high-risk patients. Antidiarrheal agents are not recommended. Probiotics such as Lactobacillus GG may reduce duration of illness. Age-appropriate feeding should continue during rehydration, emphasizing complex carbohydrates, lean proteins, fruits, vegetables, yogurt, and avoidance of fatty or high-sugar foods.
Medication Antibiotic selection depends on identified pathogens and includes agents such as TMP-SMX, erythromycin, metronidazole, vancomycin, ceftriaxone, or doxycycline when indicated. Zinc supplementation is recommended for young children.
Follow-Up Disposition
Admission criteria Surgical abdomen, inability to tolerate oral fluids, dehydration ≥10%, toxic appearance, or suspected complicated bacterial enteritis.
Discharge criteria Clinical improvement, adequate hydration, and caregivers capable of providing oral rehydration and recognizing dehydration signs.
Issues for referral Immunocompromised children, seizure-associated illness, or underlying bowel disease.
Follow-Up Recommendations Uncomplicated diarrhea usually requires no routine follow-up. Neonates and high-risk children require close outpatient reassessment.
Pearls And Pitfalls History and physical examination are key to distinguishing benign diarrhea from serious disease. Most children do not need extensive laboratory testing. Antibiotics and antidiarrheal agents have limited roles. Always consider alternative diagnoses such as appendicitis, intussusception, urinary tract infection, and sepsis.
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