Gastroenteritis (overview)

Gastroenteritis is a common illness affecting people of all ages. It is typically characterized by diarrhea, nausea, and vomiting.

Epidemiology

Gastroenteritis is a common entity, with it being one of the leading causes of mortality among children in developing countries ¹. Gastroenteritis affects both women and men equally and is distributed equally among age groups. However, morbidity and mortality of disease are bimodal in age distribution, with an increased risk of complications among children or the elderly.

Risk factors

• poor hygiene and sanitation

• proton pump inhibitors ²

Clinical presentation

The incubation period of viral gastroenteritis is typically shorter than that of bacterial gastroenteritis, lasting 1-3 days compared to 1-7 days, respectively ³. In addition, transmission of viral gastroenteritis is typically human to human, whilst bacterial gastroenteritis largely depends on the species. The duration of illness is mostly dependent on the causative organism.

Common features encountered in gastroenteritis are:

• fever

• vomiting: more common in viral

• diarrhea: can be watery or bloody with several motions a day

• nausea

• weight loss

• abdominal pain

Pathology

Gastroenteritis is commonly divided into bacterial and viral causes, although certain parasites (e.g. Giardia lamblia) can also cause it.  Typically, viral gastroenteritis is the most common cause of gastroenteritis, specifically norovirus. Below is a non-exhaustive list of the common etiologic agents:

Viral causes

• rotavirus

• norovirus

• sapovirus

• adenovirus (Mainly type 40 and 41)

Bacterial causes

• Aeromonas

• Bacillus species

• Campylobacter jejuni

• Clostridioides difficile (Clostridium difficile): common in the setting of recently commenced antibiotic use, specifically clindamycin

• Escherichia coli

• Listeria species

• Salmonella species

• Shigella species

• Vibrio species

• Yersinia enterocolitica

Radiographic findings

Plain radiograph

Abdominal x-ray is largely non-specific and non-diagnostic for gastroenteritis. Indications for x-ray are monitoring for known bacterial gastroenteritis and subsequent complications, e.g. toxic megacolon or ileus.

Ultrasound

Ultrasound is commonly performed in the pediatric setting to evaluate potential causes of abdominal pain. Diagnostic accuracy is largely operator-dependent. Findings that may be present include:

• concentric symmetrical mural thickening of the terminal ileum

• wall thickening confined to the mucosa and submucosa ⁶

CT

CT is not routinely recommended in the setting of known uncomplicated gastroenteritis. However, it can be performed in cases where there is a differential diagnosis or for the evaluation of severe complications from gastroenteritis, e.g. toxic megacolon.

Radiological features on CT are typically non-specific but include:

• bowel wall thickening (small and/or large bowel) ⁴

• hypervascular mesentery

• submucosal edema

• pericolic fat stranding

• ascites (uncommon) ⁵

However, it is important to note that the absence of such radiological features does not exclude gastroenteritis.

Treatment and prognosis

General management is typically supportive in the setting of uncomplicated disease, given the self-limiting nature of gastroenteritis ⁷. The majority of bacterial and viral gastroenteritis is managed with oral rehydration in the first instance, with intravenous dehydration as the second line when oral hydration has failed. Electrolyte replacement is common in the inpatient setting, specifically potassium replacement.

Rotovirus nowadays is commonly prevented in the setting of vaccination; therefore, best practice management of rotovirus is preventative care.

Importantly, management can be largely specific to the underlying organism, where antibiotics are recommended in some instances. Local guidelines should be consulted for specific management.

Complications

Gastroenteritis is typically self-limiting, with the majority of cases being uncomplicated. Severe complications typically include severe hypokalemia, hemolytic uremic syndrome (in the presence of E. coli) and toxic megacolon (typically, Clostridioides difficile).

Differential diagnosis

Gastroenteritis carries a broad differential consideration:

• inflammatory bowel disease

  • ulcerative colitis

  • Crohn Disease

  • microscopic colitis

• acute appendicitis

• diverticulitis

• non-infectious food poisoning

• drug induced colitis

• amoebiasis

• celiac disease