Approach to diarrhea (pediatrics): Clinical sciences

Diarrhea refers to stools that are unusually loose or frequent when compared to a patient’s normal stooling pattern. In pediatric patients, acute diarrhea is commonly caused by infection, whereas chronic diarrhea often represents a pathologic condition or a functional gastrointestinal disorder. The underlying cause of diarrhea can be determined after assessing its chronicity and associated symptoms.

Now, if a pediatric patient presents with diarrhea, first perform an ABCDE assessment to determine if they are unstable or stable. If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, administer IV fluids, and place your patient on continuous vital sign monitoring, including respiratory rate, pulse oximetry, and cardiac monitoring. Finally, if needed, don’t forget to provide supplemental oxygen.

Alright, now let’s go back to the ABCDE assessment and look at stable patients. First, obtain a focused history and physical examination. Patients or caregivers typically describe loose or frequent stools, while the physical exam might demonstrate abdominal tenderness, hyperactive bowel sounds, or dry mucous membranes. At this point, diagnose diarrhea and assess the duration of your patient’s symptoms.

First, let’s focus on acute diarrhea, or diarrhea that lasts for less than two weeks. In this case, your next step is to assess for red flag signs and symptoms, including high fever, blood or mucus in the stool, severe abdominal pain, and signs of dehydration.

If your patient reports no red flag signs or symptoms, consider mild viral gastroenteritis, which is the most common cause of acute diarrhea in children. These patients often report a known sick contact, and symptoms including vomiting and watery stool, possibly in combination with a low-grade fever. Additionally, the exam may reveal mild abdominal tenderness and increased bowel sounds. These findings are highly suggestive of mild viral gastroenteritis, which is a clinical diagnosis that doesn’t require laboratory evaluation.

This self-limited infection is commonly caused by rotavirus in unimmunized patients or by norovirus during outbreaks in closed environments like daycare centers and schools. However, if your patient has one or more red flag signs or symptoms, consider severe viral gastroenteritis or bacterial gastroenteritis. Then, order a CBC, CMP, and stool studies, including culture, viral antigen testing, and ova and parasites, or O&P.

First, let’s focus on severe viral gastroenteritis. In addition to vomiting and watery stools, these patients also report symptoms of dehydration, like decreased urine output and weight loss. Physical exam typically reveals dry mucous membranes and delayed capillary refill; and some patients may have significant abdominal tenderness.

Labs might reveal a normal anion gap hyperchloremic metabolic acidosis from bicarbonate loss in the stool. Stool studies will reveal no ova, parasites, or bacterial pathogens; and the viral antigen test will often be positive, which confirms your diagnosis of severe viral gastroenteritis.

On the flip side, individuals with bacterial gastroenteritis often have bloody stools, severe abdominal pain, and high fever. The exam may demonstrate abdominal tenderness and hyperactive bowel sounds;

while labs might show an elevated white blood cell count and normal anion gap hyperchloremic metabolic acidosis. The stool culture will identify a pathogen such as Salmonella, Shigella, Campylobacter, or E. coli; while the O&P and viral antigen tests will be negative. These findings indicate bacterial gastroenteritis.

In this case, historical clues can occasionally suggest the causative pathogen; for example, if a patient became sick after eating poultry, eggs, or dairy, think of Salmonella; while high fever and seizures suggest Shigella. Finally, recent travel suggests enterotoxigenic E. coli, and animal exposure suggests Campylobacter jejuni.

Now, switching gears and moving on to individuals with chronic diarrhea, which persists for 2 or more weeks. Again, the first step is to assess for red flag signs and symptoms, including blood in the stool, weight loss, or fever.

If any of these are present, order labs including CBC, CMP, and an ESR or CRP; and obtain stool studies, including a culture and O&P. Then, assess for bloody stools. If your patient reports bloody stools, order a fecal calprotectin, which is a sensitive marker of gastrointestinal inflammation.

An elevated fecal calprotectin should make you consider an inflammatory bowel disease like Crohn disease or ulcerative colitis. To differentiate these conditions, order an upper or lower gastrointestinal endoscopy with biopsies.

First, let’s look at findings you’ll see in Crohn disease. In this case, labs typically demonstrate a low hemoglobin; elevated platelets; elevated ESR or CRP; and negative stool studies. Endoscopic findings include cobblestoning and ulcerations with a discontinuous pattern of disease, or skip lesions; along with creeping fat anywhere along the GI tract. With these findings, diagnose Crohn disease.

Next let’s focus on findings you’ll see in ulcerative colitis. Labs will also demonstrate a low hemoglobin; elevated platelets; elevated ESR or CRP; and negative stool studies. Endoscopic findings will reveal a continuous pattern of ulcerations in the large intestine and loss of haustra, which are the pouches in the large intestine giving it a segmented appearance. With these findings, diagnose ulcerative colitis.

Here’s a clinical pearl! In addition to bloody diarrhea, fever, abdominal pain, and weight loss; patients with inflammatory bowel disease may experience extraintestinal manifestations, like polyarthralgia, uveitis, or erythema nodosum. On the other hand, if the fecal calprotectin level is normal, consider a gastrointestinal food allergy such as eosinophilic gastroenteropathy.

In this condition, patients often have a family or personal history of atopy, and many report sensitivity to cow’s milk, soy, or egg whites. Patients also demonstrate poor weight gain and may have recurrent vomiting. In severe cases, the physical exam might reveal generalized edema as a result of protein malabsorption. As far as labs go, hemoglobin is often low; eosinophils are usually elevated; and stool studies are negative.

To evaluate further, you could order a food skin-prick test or upper and lower gastrointestinal endoscopy with biopsies. The skin-prick test might identify the offending food protein. The endoscopy will show erythema, edema, erosions, or ulcerations of the intestinal mucosa; and the biopsy typically reveals eosinophilic infiltration of the gastrointestinal mucosa, which confirms eosinophilic gastroenteropathy.