What is the main differential diagnosis and next steps for a 22-year-old male presenting with less than 24 hours of emesis (vomiting) and diarrhea, accompanied by a cough and sore throat, with initial episodes of bright red blood in emesis but no subsequent hematemesis (vomiting blood) or coffee ground emesis?

Main Differential Diagnosis and Next Steps

This 22-year-old male most likely has acute viral gastroenteritis with Mallory-Weiss tear causing the initial hematemesis, and he can be managed conservatively with outpatient supportive care given his hemodynamic stability and self-limited bleeding. 1, 2

Primary Differential Diagnosis

Acute viral gastroenteritis with Mallory-Weiss tear is the leading diagnosis given:

• The constellation of vomiting, diarrhea, cough, and sore throat strongly suggests viral gastroenteritis 1
• Bright red blood only in the initial two episodes of vomiting, with no subsequent hematemesis, is classic for Mallory-Weiss tear from forceful vomiting 2, 3
• The <24-hour duration and accompanying upper respiratory symptoms point away from primary GI pathology 1
• Normal physical examination excludes hemodynamic instability and acute abdomen 3

Alternative considerations to exclude:

• Peptic ulcer disease or gastric erosions are less likely given the young age, absence of NSAID use mentioned, and self-limited bleeding pattern 2, 3
• Esophageal varices are extremely unlikely without documented liver disease or cirrhosis 2, 4
• Food protein-induced enterocolitis syndrome (FPIES) should be considered if symptoms recur with specific foods, though the acute presentation with respiratory symptoms makes viral illness more probable 1

Critical Next Steps

Immediate assessment priorities:

• Verify hemodynamic stability: check orthostatic vital signs, as orthostatic hypotension would indicate significant volume depletion requiring IV resuscitation 1, 3
• Obtain complete blood count to assess for anemia, though hemoglobin may not reflect acute blood loss initially 3
• Perform digital rectal examination to confirm stool appearance and exclude melena or ongoing bleeding 1, 3

Risk stratification using clinical features:

• This patient falls into the first category of GI bleeding (75-90% of cases): minor bleeding resolving with conservative therapy 1
• The absence of ongoing hematemesis, coffee-ground emesis, hemodynamic instability, and normal physical exam all indicate low-risk bleeding 3, 5

Management approach:

• Conservative outpatient management is appropriate given hemodynamic stability, self-limited bleeding, and likely viral etiology 1
• Initiate proton pump inhibitor therapy empirically to protect against further mucosal injury 6, 3
• Provide supportive care with oral rehydration for gastroenteritis 1
• Arrange close outpatient follow-up within 24-48 hours to reassess symptoms 1

Indications for urgent endoscopy (NOT present in this case):

• Hemodynamic instability or shock 3
• Ongoing or recurrent hematemesis 6, 3
• Hemoglobin <7 g/dL or significant drop from baseline 3
• Age >65 years with comorbidities 4, 7
• Failure to respond to conservative management 1

Common Pitfalls to Avoid

Do not automatically pursue urgent endoscopy in hemodynamically stable patients with coffee-grounds emesis or self-limited bright red hematemesis, as significantly fewer high-risk lesions are found in these patients compared to those with ongoing bloody emesis 5

Do not overlook non-GI diagnoses in patients presenting with coffee-grounds emesis or minimal hematemesis, as serious conditions like myocardial infarction, pulmonary embolism, and sepsis can present with GI symptoms 5

Do obtain detailed medication history to identify NSAID use, antiplatelet agents, or anticoagulants that significantly increase bleeding risk, though this appears less relevant in this young patient 2, 4, 3

Do not delay evaluation if symptoms worsen or bleeding recurs, as endoscopy should be performed within 24 hours if clinical deterioration occurs 2, 6, 3

Consider viral gastroenteritis as the primary diagnosis when vomiting and diarrhea occur with respiratory symptoms in a young, otherwise healthy patient, as this is the most common cause of acute gastroenteritis accounting for the majority of cases 1