What is the best course of action for a 21-year-old male with nausea, epigastric pain, loss of appetite, abdominal tenderness to palpation (TTP), and no bowel movement since yesterday, suspected to have viral gastroenteritis (GE)?

Clinical Assessment and Management

While viral gastroenteritis is a reasonable consideration, the bilateral lateral abdominal tenderness with light palpation in a young male with epigastric pain and constipation raises concern for early appendicitis or other surgical pathology that must be ruled out before attributing symptoms to a benign viral illness. 1

Critical Red Flags to Evaluate Immediately

The physical examination finding of tenderness to palpation (TTP) in the bilateral outer abdomen is atypical for uncomplicated viral gastroenteritis and warrants careful consideration of alternative diagnoses:

• Appendicitis can present with atypical pain patterns, particularly in young adults, and the absence of classic right lower quadrant findings does not exclude it 1
• Bilious vomiting would require immediate imaging to rule out malrotation with volvulus, though this is not reported in your case 1
• Constipation with no bowel movement since yesterday combined with abdominal pain could indicate early bowel obstruction or other surgical pathology 2

Features Supporting Viral Gastroenteritis

If viral gastroenteritis is the diagnosis, certain clinical features should be present:

• Sudden onset of symptoms with nausea and vomiting typically beginning abruptly 1
• Low-grade fever only (high fever >39°C occurs in only one-third of viral cases) 1
• Diarrhea developing 24-48 hours after vomiting starts, which should be watery and never bloody 1
• Duration of illness typically 12-60 hours for Norovirus or 3-8 days for rotavirus 1
• Exposure history to others with similar symptoms in military barracks or group settings 1

Features Against Viral Gastroenteritis in This Case

Several aspects of this presentation are concerning:

• Prominent epigastric pain is less typical for viral gastroenteritis, which usually causes diffuse cramping 1
• Bilateral lateral abdominal TTP is not a characteristic finding of viral gastroenteritis 1
• Absence of diarrhea at this stage (though it can develop later) 1
• Constipation is not typical of viral gastroenteritis 2

Recommended Immediate Actions

Perform a more detailed abdominal examination focusing on:

• Rebound tenderness, guarding, or rigidity that would indicate peritoneal irritation 1
• McBurney's point tenderness and psoas/obturator signs for appendicitis 1
• Bowel sounds to assess for ileus or obstruction 2
• Rectal examination if indicated to assess for occult blood or masses 2

Obtain basic laboratory studies including:

• Complete blood count - mild leukocytosis can occur with viral gastroenteritis but marked elevation suggests bacterial infection or appendicitis 1
• Basic metabolic panel to assess hydration status and electrolytes 2
• Urinalysis to rule out urinary tract infection or kidney stones as alternative diagnoses 1

Management If Viral Gastroenteritis Is Confirmed

If surgical pathology is excluded and viral gastroenteritis is the diagnosis:

Hydration is the cornerstone of treatment:

• Oral rehydration solution (ORS) is first-line therapy for mild to moderate dehydration and should be started immediately 2, 3
• Isotonic intravenous fluids (lactated Ringer's or normal saline) are indicated only for severe dehydration, shock, altered mental status, or failure of ORS 2
• Encourage 8-10 large glasses of clear liquids daily while eliminating lactose-containing products 4

Antiemetic therapy can facilitate oral rehydration:

• Ondansetron may be given to facilitate tolerance of oral rehydration in adults with acute gastroenteritis associated with vomiting 2, 3
• Monitor QTc interval if using ondansetron, particularly if combined with other QT-prolonging medications 2, 5

Antimotility agents:

• Loperamide may be given to immunocompetent adults with acute watery diarrhea once it develops 2
• Avoid antimotility drugs if there is fever or concern for inflammatory diarrhea 2

No antibiotics are indicated for presumed viral gastroenteritis, as they provide no benefit and may cause harm 1

When to Seek Urgent Re-evaluation

Instruct the patient to return immediately if:

• Bloody diarrhea develops with fever or severe cramping 4
• Abdominal pain worsens or localizes to the right lower quadrant 1
• Vomiting becomes bilious (green or yellow) 1
• Signs of severe dehydration develop including decreased urination, dizziness, or altered mental status 2
• Fever exceeds 39°C or persists beyond 48 hours 1

Common Pitfalls to Avoid

• Do not assume viral gastroenteritis without considering surgical causes of abdominal pain, particularly with atypical examination findings 1
• Do not delay rehydration while pursuing diagnostic testing if viral gastroenteritis is suspected 1
• Do not prescribe antibiotics empirically without evidence of bacterial infection 1
• Do not rely solely on the absence of diarrhea to rule out gastroenteritis, as vomiting often precedes diarrhea by 24-48 hours 1

Given the atypical examination findings with bilateral lateral abdominal tenderness, strongly consider surgical consultation or imaging (CT abdomen/pelvis) if symptoms worsen, pain localizes, or the patient does not improve within 24 hours. 1