Management of Acute Gastroenteritis with Hematemesis
This patient requires immediate assessment for hemodynamic stability, urgent stool studies including culture and Shiga toxin testing, and supportive care with oral rehydration therapy while avoiding empiric antibiotics until STEC is excluded. 1, 2
Immediate Risk Stratification
Hematemesis in the setting of acute gastroenteritis is a red flag requiring urgent evaluation. 2 The presence of "red emesis" (hematemesis) combined with bloody diarrhea, abdominal pain, and fever suggests either:
- Severe inflammatory/invasive bacterial enterocolitis (Salmonella, Shigella, Campylobacter, STEC) 1, 3
- Upper GI bleeding from severe retching/vomiting (Mallory-Weiss tear) 4
- STEC infection with potential for hemolytic uremic syndrome (HUS) 1, 2
Critical Diagnostic Steps
Obtain stool studies immediately before any antibiotic administration: 1, 2
- Stool culture for Salmonella, Shigella, Campylobacter, and STEC O157:H7 1
- Shiga toxin testing (PCR or EIA) for all STEC serotypes 1, 2
- Fecal leukocytes or lactoferrin (positive in 60-95% of Shigella, 25-80% of Campylobacter) 1
- C. difficile testing if recent antibiotic exposure or healthcare contact 1
Laboratory assessment for complications: 2
- Complete blood count (assess for hemolytic anemia suggesting HUS) 2
- Comprehensive metabolic panel (electrolytes, renal function, acidosis) 4, 2
- Blood cultures if fever >38.5°C or signs of sepsis 1
Antibiotic Decision Algorithm
DO NOT give empiric antibiotics until STEC is excluded because fluoroquinolones, β-lactams, TMP-SMX, and metronidazole increase HUS risk 17-fold in STEC O157 and Shiga toxin 2-producing strains. 1, 2
If STEC testing is negative AND patient has:
- Fever + bloody diarrhea + moderate-to-severe illness → Give empiric fluoroquinolone (ciprofloxacin 500mg PO BID) or azithromycin 500mg PO daily depending on local resistance patterns 1
- Signs of sepsis or suspected enteric fever → Give broad-spectrum IV antibiotics after cultures obtained 1
For children <3 months or with neurologic symptoms: Give third-generation cephalosporin empirically 1
Supportive Management
Aggressive oral rehydration is the cornerstone of treatment: 5, 6
- Oral rehydration solution 50-100 mL/kg over 3-4 hours for mild-moderate dehydration 5
- Small frequent volumes (5 mL every minute initially) even if vomiting continues 5
Antiemetic therapy for persistent vomiting: 7, 5
- Ondansetron 4-8mg sublingual (adults) or 0.15 mg/kg (children ≥4 years, max 16mg) 7, 5
- Screen for cardiac disease before ondansetron due to QT prolongation risk 5
- Add metoclopramide 5-10mg PO if ondansetron insufficient, but avoid in children due to dystonic reactions 7, 5
IV fluids only if: 5
- Severe dehydration with hemodynamic instability 5
- Altered mental status 5
- Failed oral rehydration after ondansetron 5
Critical Pitfalls to Avoid
Never use antimotility agents (loperamide) in bloody diarrhea as this increases risk of toxic megacolon and HUS in STEC infections. 1, 5
Avoid antibiotics in confirmed STEC O157 or Shiga toxin 2-producing strains even if patient appears severely ill, as treatment worsens outcomes. 1, 2
Do not delay stool culture collection while waiting for antibiotic susceptibility data—empiric treatment can be modified based on culture results. 1
Monitor for HUS development (hemolytic anemia, thrombocytopenia, acute kidney injury) in any patient with bloody diarrhea, particularly days 5-13 after symptom onset. 2
Disposition and Follow-up
- Hemodynamic instability or severe dehydration 2
- Inability to tolerate oral intake after antiemetic trial 1
- Severe abdominal pain suggesting possible surgical abdomen 1
- Immunocompromised state 1
- Laboratory evidence of HUS or severe electrolyte abnormalities 2
Outpatient management acceptable if: 8