What is the best course of action for a baby with blood in stool, good weight gain, and no other symptoms like fever?

Management of a Baby with Blood in Stool, Good Weight Gain, and No Other Symptoms

The most appropriate management for a baby with blood in stool but good weight gain and no other symptoms is to consider food protein-induced allergic proctocolitis (FPIAP) as the likely diagnosis and implement a maternal elimination diet if breastfeeding or switch to a hydrolyzed formula if formula feeding.

Initial Assessment

• Blood in stool in an otherwise healthy infant with good weight gain and no fever most commonly indicates food protein-induced allergic proctocolitis (FPIAP), especially in breastfed infants 1, 2
• Good weight gain is a reassuring sign that distinguishes this condition from more serious pathologies like necrotizing enterocolitis (NEC), which typically presents with additional symptoms such as abdominal distension, apnea, bradycardia, and bilious emesis 3
• The absence of fever further supports a non-infectious etiology 4

Diagnostic Considerations

• Visible blood in stool requires investigation to rule out serious conditions, but in an otherwise healthy infant with good weight gain, invasive testing can often be avoided 1
• Common causes to consider include:
  • Cow's milk protein allergy (most common food trigger at 94.5% of cases) 2
  • Other food protein allergies (egg 37.4%, beef 10.9%, wheat 5.5%) 2
  • Maternal blood ingestion (melena neonatorum) 5
  • Less likely: infectious colitis, anal fissures 1

Recommended Management Approach

For Breastfed Infants:

• Implement a 2-4 week maternal elimination diet that restricts at least milk and egg 4
• This approach is recommended as first-line treatment since cow's milk protein ingested by the mother may be expressed in breast milk 4
• Continue breastfeeding during the elimination period 4

For Formula-Fed Infants:

• Switch to an extensively hydrolyzed protein formula or amino acid-based formula 4
• Thickened formulas may be considered if reflux symptoms are also present 4

Expected Response to Dietary Changes

• Blood in stool typically resolves within a median of 3 days (range 1-14.5 days) after dietary elimination 2
• Mucus in stool may take longer to resolve (median 30 days) 2
• A two-week elimination period is generally sufficient to determine if the suspected food is causing the bleeding 2

Follow-up Recommendations

• If symptoms resolve with dietary elimination, continue the diet for 4-6 months before considering reintroduction of eliminated foods 1, 2
• If symptoms persist despite dietary changes, consider:
  • Additional food eliminations if multiple food allergies are suspected, especially in infants with atopic dermatitis or elevated eosinophil counts (≥300 cells/μL) 2
  • Further evaluation to rule out other causes 1

When to Consider Further Investigation

• Persistent bleeding despite dietary changes 1
• Development of additional symptoms such as:
  • Poor weight gain or growth 4
  • Fever or signs of infection 4
  • Abdominal distension or vomiting 3
• Early onset of bleeding (before 2 months of age) may represent transient bleeding rather than FPIAP 2

Important Caveats

• Avoid unnecessary antibiotic treatment as this is rarely an infectious process in an otherwise well infant 4
• Avoid invasive procedures like colonoscopy as first-line investigation in an otherwise healthy infant with isolated blood in stool 1
• Recognize that most cases are self-limiting, with excellent prognosis even without specific treatment 1
• Formal diagnosis of cow's milk protein allergy requires elimination and subsequent challenge to avoid unnecessary long-term dietary restrictions 1

By following this approach, most infants with blood in stool but good weight gain and no other symptoms will improve with simple dietary modifications, avoiding unnecessary interventions while ensuring appropriate management of this concerning but typically benign condition.