What is the appropriate management of an adult patient presenting with small‑bowel diarrhea?

Management of Small Bowel Diarrhoea

The most critical intervention in small bowel diarrhoea is immediate rehydration with oral rehydration solutions (ORS) for mild-to-moderate cases, escalating to intravenous fluids only when severe dehydration, shock, or altered mental status is present. 1, 2

Initial Severity Assessment and Risk Stratification

Immediately evaluate for warning signs that mandate hospitalization and aggressive management 1, 3:

• High fever (>38.5°C), bloody stools, or severe vomiting
• Clinical dehydration (assess mental status, pulse, skin turgor, mucous membranes) 1
• Age >75 years, immunocompromised status, or significant systemic illness 1, 2
• Persistent symptoms beyond 48 hours without improvement 1, 3

Common pitfall: Do not delay rehydration while pursuing diagnostic workup—hydration is the priority regardless of etiology. 1, 2

Rehydration Strategy: The Cornerstone of Management

Mild-to-Moderate Dehydration

Start with oral rehydration therapy (ORT) as first-line treatment 4, 1:

• Use reduced osmolarity ORS (65-70 mEq/L sodium, 75-90 mmol/L glucose) 4, 2
• Administer 50-100 mL/kg over 2-4 hours until clinical dehydration corrects 2
• Total daily fluid prescription: 2200-4000 mL/day 4
• In otherwise healthy adults, glucose-containing drinks or electrolyte-rich soups may suffice 1, 3

Evidence note: Formal ORS does not reduce stool volume or duration but prevents life-threatening dehydration—this is its primary value. 1

Severe Dehydration (Grade 3-4)

Immediately initiate intravenous rehydration 4:

• Use isotonic saline or lactated Ringer's solution 4, 2
• If tachycardic or potentially septic: give initial bolus of 20 mL/kg 4
• Target urine output >0.5 mL/kg/h 4, 3
• Rate must exceed ongoing losses (urine output + 30-50 mL/h insensible losses + GI losses) 4

Caution in elderly: Monitor closely for fluid overload, especially with heart or kidney failure. 4

Pharmacological Management

Loperamide: First-Line Symptomatic Relief

Initiate loperamide 4 mg, then 2 mg after each unformed stool (maximum 16 mg/day) 4, 1, 3:

• Safe and effective in uncomplicated watery diarrhoea 1, 3
• The outdated belief that antimotility agents "trap toxins" is not evidence-based 3

Absolute contraindications 1, 2:

• Bloody diarrhoea or dysentery
• High fever or suspected inflammatory diarrhoea
• Children <18 years of age
• Immunocompromised patients with suspected neutropaenic enterocolitis 4

Octreotide: For Refractory Cases

For severe or refractory small bowel diarrhoea unresponsive to loperamide 4, 3:

• Start 100-150 mcg subcutaneously three times daily
• Can escalate to 500 mcg three times daily until controlled 4
• Consider 25-50 mcg/h IV infusion if severely dehydrated 4

Antimicrobial Therapy: Highly Selective Use Only

Do NOT give empiric antibiotics for routine acute watery diarrhoea 1, 2:

• Reserve for traveler's diarrhoea, proven bacterial pathogens, or dysentery (bloody stools + fever + abdominal cramps) 1, 2
• If dysentery suspected: azithromycin 500 mg daily for 3 days or 1 gram single dose 2
• Rifaximin indicated only for traveler's diarrhoea from noninvasive E. coli 5

Critical warning: Avoid antibiotics in STEC infections—increases hemolytic uremic syndrome risk. 2

Nutritional Management

Resume normal eating immediately during or after rehydration, guided by appetite 1, 2:

• Small, light meals avoiding fatty, heavy, spicy foods and caffeine 1, 3
• No evidence supports fasting or restrictive dieting 1
• Consider avoiding lactose-containing foods (except yogurt, firm cheeses) if diarrhoea persists beyond several days 3

For infants: Continue breastfeeding throughout the episode. 2

Special Consideration: Neutropaenic Enterocolitis

If immunocompromised with neutropaenia, suspect neutropaenic enterocolitis and manage aggressively 4:

• Broad-spectrum antibiotics covering gram-negatives, gram-positives, and anaerobes (piperacillin-tazobactam or imipenem-cilastatin, or cefepime/ceftazidime + metronidazole) 4
• G-CSF, nasogastric decompression, bowel rest, serial abdominal exams 4
• Avoid anticholinergics, antidiarrhoeals, and opioids—they worsen ileus 4
• Consider amphotericin if no response to antibacterials (fungaemia common) 4

Surgical intervention indicated for: persistent GI bleeding despite correction of coagulopathy, free perforation, abscess formation, or clinical deterioration despite aggressive measures. 4

When to Hospitalize

Admit immediately if 4, 1:

• Severe dehydration, sepsis, or altered mental status
• Neutropaenia with diarrhoea
• No improvement within 48 hours or worsening symptoms
• Development of bloody stools, persistent high fever, severe vomiting, or abdominal distension

Diagnostic Testing

Most cases do not require stool cultures or laboratory workup 2:

• Reserve testing for: bloody diarrhoea, immunocompromised patients, persistent fever, or suspected nosocomial infection 4, 2
• If testing pursued: evaluate for C. difficile, Salmonella, E. coli, Campylobacter 4

Key algorithmic approach: Assess severity → Rehydrate appropriately (oral vs. IV) → Add loperamide if uncomplicated watery diarrhoea → Escalate to octreotide if refractory → Reserve antibiotics for specific indications only → Resume normal diet immediately.