What is the appropriate evaluation and management of diarrhea?

Evaluation and Management of Diarrhea

The cornerstone of diarrhea management is oral rehydration solution (ORS) for mild to moderate dehydration, with intravenous fluids reserved for severe dehydration, shock, or altered mental status. 1

Initial Clinical Assessment

History and Physical Examination

Obtain a focused history evaluating:

• Onset, duration, and frequency of symptoms - distinguish acute (<14 days) from persistent (≥14 days) diarrhea 1, 2
• Stool characteristics - watery vs. bloody/mucoid vs. purulent to differentiate inflammatory from noninflammatory causes 1, 3
• Volume depletion signs - thirst, tachycardia, orthostasis, decreased urination, lethargy, decreased skin turgor 1, 2
• Associated symptoms - fever, tenesmus, abdominal pain, nausea, vomiting, altered mental status 1, 3

Assess epidemiological risk factors:

• Recent travel to developing areas 1, 2
• Day-care attendance or employment 1
• Consumption of unsafe foods (raw meats, eggs, shellfish, unpasteurized products) or untreated water 1
• Contact with ill persons or animals 1
• Recent antibiotic use 1, 2
• Immunocompromising conditions (AIDS, immunosuppressive medications, extremes of age) 1, 3
• Occupation as food handler or caregiver 1

Severity Grading

Classify dehydration severity clinically:

• Mild to moderate dehydration - manageable with oral rehydration 1
• Severe dehydration - requires intravenous therapy when accompanied by shock, altered mental status, or ORS failure 1

Diagnostic Testing

Most patients do not require laboratory workup or routine stool cultures. 2, 4

Reserve diagnostic investigation for:

• Severe dehydration or illness 2, 3
• Persistent fever 2, 3
• Bloody or mucoid stools 2, 3
• Immunosuppression 2, 3
• Suspected nosocomial infection or outbreak 2
• Recent hospitalization 3

When testing is indicated, molecular studies are preferred over traditional stool cultures unless an outbreak is suspected. 3

Rehydration Therapy

Oral Rehydration (First-Line)

Reduced osmolarity ORS (<250 mmol/L) is the first-line therapy for mild to moderate dehydration in all age groups. 1

ORS administration protocol:

• Mild to moderate dehydration: Administer 50-100 mL/kg over 2-4 hours until clinical dehydration is corrected 1
• Give in frequent, small amounts - successful in >90% of cases 4
• Nasogastric administration may be considered for moderate dehydration when oral intake is not tolerated 1

Available ORS formulations include Pedialyte, CeraLyte, and Enfalac Lytren. 1 Popular beverages like apple juice, Gatorade, and soft drinks should NOT be used for rehydration. 1

Important caveat: Standard ORS protocols should NOT be used for hypernatremic dehydration, as they contain 50-90 mEq/L sodium and will not adequately correct hypernatremia. 5

Intravenous Rehydration

Isotonic IV fluids (lactated Ringer's or normal saline) are indicated when:

• Severe dehydration with shock or altered mental status is present 1
• ORS therapy fails 1
• Ileus is present 1
• Ketonemia prevents tolerance of oral rehydration 1

Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS for remaining deficit replacement. 1

Maintenance and Ongoing Losses

Once rehydrated, replace ongoing stool losses with ORS until diarrhea and vomiting resolve. 1

Nutritional Management

Continue breastfeeding throughout the diarrheal episode in infants. 1

Resume age-appropriate usual diet immediately after or during rehydration. 1 Early feeding (within 12 hours) is as safe and effective as delayed feeding and improves nutritional outcomes. 1

Oral zinc supplementation (20 mg daily for 10-14 days) reduces diarrhea duration in children 6 months to 5 years in areas with high zinc deficiency prevalence or malnutrition. 1

Antimicrobial Therapy

In most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is NOT recommended. 1

Exceptions for empiric treatment:

• Immunocompromised patients 1
• Ill-appearing young infants 1
• Suspected enteric fever - treat empirically after cultures with broad-spectrum therapy 1

Avoid empiric treatment in persistent watery diarrhea lasting ≥14 days. 1

Modify or discontinue antimicrobials when a clinically plausible organism is identified. 1

Critical warning: Antimicrobial therapy for STEC O157 and other STEC producing Shiga toxin 2 should be AVOIDED due to risk of hemolytic uremic syndrome. 1

Adjunctive Therapies

Antimotility Agents

Loperamide may be given to immunocompetent adults with acute watery diarrhea. 1

Absolute contraindications:

• Children <18 years of age 1
• Bloody diarrhea 1, 2
• Fever 1
• Suspected inflammatory diarrhea (risk of toxic megacolon) 1

Antiemetics

Ondansetron may be given to children >4 years and adolescents with vomiting to facilitate oral rehydration tolerance. 1

Probiotics

Probiotic preparations may be offered to reduce symptom severity and duration in immunocompetent patients with infectious or antimicrobial-associated diarrhea. 1

Common Pitfalls to Avoid

• Do NOT use antimotility agents as substitute for fluid and electrolyte therapy - they are ancillary only after adequate hydration 1
• Do NOT treat asymptomatic contacts - advise infection control measures instead 1
• Do NOT give antibiotics for STEC infections - increases risk of complications 1
• Do NOT use commercial sports drinks or juices for rehydration - inappropriate electrolyte composition 1
• Do NOT routinely order stool cultures - reserve for specific high-risk scenarios 2, 3