Infectious gastroenteritis: Clinical sciences

Gastroenteritis refers to inflammation of the gastrointestinal tract, typically caused by infectious pathogens. These pathogens injure the intestinal lining, leading to fluid shifts and water loss through diarrhea and vomit. The diagnosis of what’s causing gastroenteritis is made by first evaluating whether the patient’s diarrhea is watery or bloody, as well as identifying common pathogens such as bacteria, viruses, or parasites.

Now, if you suspect gastroenteritis, you should perform an ABCDE assessment to determine if your patient is unstable or stable.

If the patient is unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, start IV fluids, and begin continuous vital sign monitoring including blood pressure, heart rate, and oxygen saturation. Provide supplemental oxygen if needed, and start broad spectrum antibiotics. Okay, let’s go back to the ABCDE assessment and take a look at stable patients.

First, start by taking a focused history and physical exam. Your patient may report diarrhea, nausea, vomiting, and abdominal pain. Other common symptoms include flatulence, fecal urgency, and possibly fever.

On the other hand, physical exam findings will reveal abdominal tenderness, and may show signs of dehydration, such as dry skin and mucous membranes, decreased skin turgor, and decreased capillary refill time. At this point, you should suspect gastroenteritis.

Here’s a clinical pearl! Be sure to always clarify stool frequency and consistency whenever taking a history. Diarrhea is defined as passing of three or more unformed stools in 24 hours. If your patient is passing formed stools, or has not had multiple episodes per day, they do not have diarrhea.

Once you suspect gastroenteritis, determine if the diarrhea is watery or bloody. Let’s first talk about watery diarrhea.

If your patient has watery diarrhea, first assess the patient’s level of dehydration. Signs of mild dehydration include mild tachycardia, dry skin and mucous membranes, decreased skin turgor, and slightly delayed capillary refill time. If your patient has mild dehydration, provide supportive care, which includes oral rehydration therapy, or ORT for short. Then, assess your patient’s response to treatment in 24 to 48 hours. If the response is adequate, and your patient is able to maintain hydration with ORT, then you can diagnose acute gastroenteritis. In this case, continue current management until diarrhea resolves. If the response is inadequate, and your patient cannot maintain hydration with ORT, proceed with management for moderate to severe dehydration.

So, let’s go back to the assessment of dehydration. Individuals with moderate to severe dehydration typically present with signs of hypovolemia, such as tachycardia and tachypnea, very dry skin and mucous membranes, decreased skin turgor, and delayed capillary refill time.

Additionally, your patient may present with sunken eyes, decreased urine output, fatigue, weakness, and even altered mental status.

Here’s a clinical pearl! Although lab tests aren’t required for most patients with acute diarrhea, some labs can help assess the level of dehydration, such as ordering a BMP to look for hypokalemia or acute kidney injury.

If your patient presents with moderate to severe dehydration, be sure to start IV fluids for rehydration. Additionally, consider starting empiric antibiotics, and giving bismuth subsalicylate and an antimotility agent like loperamide.

Next, assess travel history. If the patient has recently traveled, you can diagnose traveler’s diarrhea, which is typically caused by Enterotoxigenic Escherichia coli or ETEC for short. In this case, you should continue the current management with bismuth subsalicylate and an antimotility agent until diarrhea resolves, while antibiotic therapy is reserved for patients with severe diarrhea.

On the other hand, if your patient does not have a history of recent travel, order an enteric pathogen panel and assess the results. If no pathogen is identified, continue the current management plan and assess the patient’s response to treatment. If the response is inadequate, you should consider an alternative diagnosis. If the response is adequate, however, you can confirm the diagnosis of acute gastroenteritis and again, continue current management until diarrhea resolves.