💩 Acute Diarrhea · Infectious & Dehydration Decision Tool

Schwartz Clinical Handbook — Chapter 27 · Viral vs bacterial · Bloody diarrhea · Rotavirus · Salmonella · Shigella · Campylobacter · C. diff · HUS

Select stool characteristics (watery, bloody, mucous), fever, vomiting, travel/exposure, and dehydration signs → differentiate viral gastroenteritis from bacterial/parasitic enteritis, and guide stool studies, antibiotics, and ORT.
⚠️ Red flags: bloody diarrhea, high fever, toxic appearance, oliguria, HUS risk (pallor, petechiae).

📋 Step 1 — Stool & clinical features
📌 Diagnostic impressions
📖 Schwartz Ch 27

Select stool pattern (watery vs bloody), fever, mucus, duration, travel/antibiotic history, and dehydration signs → system suggests viral (rotavirus, norovirus), bacterial (Salmonella, Shigella, Campylobacter, C. diff), or parasitic (Giardia) and recommends hydration, ORT, or stool culture/antibiotics.

✔️ Watery + vomiting + low fever → viral.
✔️ Bloody + high fever + tenesmus → bacterial (Shigella, Salmonella, Campylobacter).
✔️ Bloody + afebrile + no vomiting → possible intussusception / Meckel.
✔️ Antibiotic exposure → C. diff.
📘 Schwartz pearls (Chapter 27)
• ORT with low‑osmolarity solution (75 mEq/L Na) is first line.
• Antidiarrheals contraindicated in infectious diarrhea (risk of prolonged illness / toxic megacolon).
• Stool culture: if bloody, severe, daycare, immunocompromised, or persistent.
• HUS triad: anemia, thrombocytopenia, renal failure (E. coli O157:H7).