Management of Diarrhoea - OPD Case

1. Definition & Classification

• Acute diarrhoea: Sudden onset, lasting <14 days (most OPD cases fall here)
• Persistent diarrhoea: 14 days to 4 weeks
• Chronic diarrhoea: >4 weeks (needs workup beyond OPD)
• Dysentery: Bloody/mucoid stools (implies invasive pathogen - Shigella, E. histolytica, Campylobacter)

2. Initial Assessment in OPD

History (Key Questions)

• Onset, duration, frequency of stools
• Presence of blood, mucus, or pus in stool
• Associated vomiting, fever, abdominal cramps
• Recent travel, food history, water source, sick contacts
• Recent antibiotic use (think C. difficile)
• Past medical history (immunocompromised, IBD, DM, HIV)
• Vaccine status (in children)

Assess Dehydration Status

Children may maintain normal BP/HR even in severe dehydration - do not rely on BP alone.

3. Investigations (Not Routine - Guide by Clinical Severity)

• Systemic involvement (high fever, toxic appearance, sepsis signs)
• Bloody/mucoid stool (dysentery)
• Moderate-severe dehydration
• Duration >2 weeks
• Immunocompromised, extremes of age
• Suspected outbreak

• Stool culture & sensitivity - for dysentery, prolonged course, systemic illness
• Stool for ova & parasites - travel history, duration >2 weeks (Giardia, E. histolytica, Cryptosporidium)
• Stool for C. difficile toxin - recent antibiotics, hospitalization
• CBC - check for leukocytosis (C. difficile), eosinophilia (parasites), anaemia (STEC/HUS)
• BMP/electrolytes - moderate-severe dehydration
• Stool PCR/multiplex panel (culture-independent tests) - faster results, increasingly used

Fecal leukocytes alone are not specific enough to determine antibiotic need. - Rosen's Emergency Medicine.

4. Aetiology at a Glance

5. Management

A. Oral Rehydration Therapy (ORT) - CORNERSTONE

• Rehydration phase: 50-100 mL/kg over 2-4 hours (mild: 50 mL/kg; moderate: 100 mL/kg)
• Maintenance: 10 mL/kg for each loose stool; 2 mL/kg for each vomit episode
• Give in small frequent sips, not large boluses
• Nasogastric tube ORT is an option if the child cannot drink

B. Diet / Feeding

• Continue feeding - do NOT starve the patient (old practice of NPO is discouraged)
• Early refeeding reduces intestinal permeability and shortens illness duration
• Avoid: high-fat foods, high-sugar juices (worsen osmotic diarrhoea), lactose (if lactase deficiency post-gastroenteritis)
• BRAT diet (Banana, Rice, Applesauce, Toast) - acceptable, but a balanced diet is preferred

C. Zinc Supplementation (Children)

• Children <5 years: Zinc 20 mg/day x 10-14 days (WHO recommendation)
• Reduces duration and severity; reduces recurrence in next 2-3 months
• Under 6 months: 10 mg/day

D. Antimotility Agents

• Loperamide (Imodium): Useful in adults with watery non-bloody diarrhoea for symptom relief
  • Dose: 4 mg initially, then 2 mg after each loose stool (max 16 mg/day)
  • Avoid in: bloody diarrhoea, suspected invasive infection, children <2 years, C. difficile
• Bismuth subsalicylate: Reduces stool frequency; mild antisecretory effect

E. Antiemetics

• Ondansetron (5-HT3 antagonist): Reduces vomiting, improves ORT tolerance, reduces IV fluid need and hospitalization
  • Children: 0.15 mg/kg/dose; Adults: 4-8 mg PO
  • Use when vomiting is impairing ORT

F. Antibiotics - When & What

Antibiotics are NOT needed for viral gastroenteritis (most cases) or uncomplicated bacterial diarrhoea in healthy patients. They prolong Salmonella excretion and increase HUS risk with STEC (E. coli O157:H7).

G. Probiotics

• Evidence supports modest reduction in duration of acute viral gastroenteritis (by ~1 day), particularly in children
• Lactobacillus rhamnosus GG and Saccharomyces boulardii have the best evidence
• Recent 2025 meta-analysis (PMID: 40739406) confirms benefit in reducing duration and severity of acute gastroenteritis in children

6. Red Flags - Refer / Admit

7. Discharge Instructions & Counselling

• Signs to return: worsening dehydration, blood in stool, no improvement in 48-72 hours, high fever
• Hand hygiene - soap and water (not just hand sanitizer for Norovirus, C. difficile)
• Safe drinking water, food hygiene
• Continue breast feeding in infants
• Rotavirus vaccine for children (prevents the leading cause of severe viral gastroenteritis)
• Return for follow-up if diarrhoea persists >7 days

Summary Algorithm

Diarrhoea OPD patient
        ↓
Assess dehydration → Severe? → IV fluids + admit
        ↓ Mild/Moderate
Oral Rehydration Solution + Continue feeding
        ↓
Bloody? Fever? Travel? Immunocompromised?
  YES → Stool culture, consider antibiotics
  NO  → Symptomatic (Zinc in children, Loperamide in adults, Ondansetron for vomiting)
        ↓
Reassess in 24-48 hrs → No improvement → Investigate further