What are the differential diagnoses for blood-stained stool in pediatric and neonate patients?

Differential Diagnoses for Blood-Stained Stool in Pediatric and Neonatal Patients

Most Common Causes by Age Group

In neonates and young infants, cow's milk protein allergy (CMPA) is the most common cause of bloody stools (53.3% of cases), followed by swallowed maternal blood syndrome, viral enteritis, and necrotizing enterocolitis (NEC). 1

Neonatal Period (0-28 days)

Benign/Non-Surgical Causes:

• Cow's milk protein allergy (CMPA) - accounts for over half of all cases, typically presents in exclusively formula-fed or mixed-fed infants, though can occur in breastfed infants through maternal dietary proteins 1
• Swallowed maternal blood syndrome - second most common cause (10% of cases), presents within first 1-3 days of life, confirmed by alkali denaturation test (Apt test) 1, 2
• Food protein-induced allergic proctocolitis (FPIAP) - often overlooked differential, presents with bloody stools in otherwise well-appearing infants 3
• Anal fissure - accounts for 5% of cases, visible on external examination 1
• Vitamin K deficiency bleeding - consider if circumcision performed or inadequate prophylaxis given, presents with prolonged INR/PT/PTT 4

Infectious Causes:

• Viral enteritis - represents 9.7% of cases 1
• Bacterial enteritis - Salmonella, Shigella, Campylobacter, Yersinia, though less common in neonates 5, 6

Surgical/Life-Threatening Causes:

• Necrotizing enterocolitis (NEC) - most common surgical cause (8.3% of cases), higher incidence in preterm infants, presents with abdominal distension, bilious emesis, and systemic signs 1, 7
• Volvulus/malrotation - rare but critical, presents with bilious emesis and acute deterioration 5
• Hirschsprung disease - presents with delayed meconium passage, abdominal distension 5

Older Infants and Children (>1 month)

Infectious Causes (Most Common):

• Campylobacter infection - presents with fever (47-91% of cases), severe abdominal cramping (>90% in older children), bloody diarrhea appearing 2-4 days after initial watery diarrhea 8
• Shigella (bacillary dysentery) - frequent scant bloody stools with mucus, tenesmus, fever, abdominal tenderness 5, 6
• Shiga toxin-producing E. coli (STEC) - approximately 65% have bloody diarrhea, abdominal tenderness without fever is characteristic, risk of hemolytic uremic syndrome (HUS) 5
• Salmonella enterica - bloody diarrhea with fever, systemic symptoms 5
• Yersinia enterocolitica - mimics appendicitis with right lower quadrant pain 5
• Clostridioides difficile - particularly in children with recent antibiotic exposure 5, 9

Inflammatory Bowel Disease:

• Ulcerative colitis - persistent bloody diarrhea beyond 48 hours, hypogastric pain, mucoid stools 5, 9
• Crohn's disease - more common in older children/adolescents, may present with colitis in pediatric onset, granulomas found in 67% at initial colonoscopy 5

Other Causes:

• Intussusception - crampy intermittent abdominal pain, "currant jelly" stools, lethargy, unusual before 3 months of age 5
• Meckel's diverticulum - painless bright red blood per rectum
• Juvenile polyps - painless bright red blood coating stool

Critical Clinical Assessment Points

Immediate Evaluation Priorities:

• Assess hydration status first - check skin turgor (>2 seconds indicates severe dehydration), capillary refill time, mucous membrane moisture, mental status, as dehydration is the primary cause of mortality 5, 9
• Distinguish bilious from non-bilious vomiting - bilious emesis suggests obstruction distal to ampulla of Vater requiring urgent surgical evaluation 5
• Examine stool character - frequent scant bloody stools with mucus suggests bacillary dysentery; large volume bloody diarrhea suggests STEC or inflammatory process 5
• Check vital signs - fever ≥38.5°C with bloody diarrhea warrants blood cultures and consideration of empiric antibiotics in high-risk groups 6, 9

Age-Specific Diagnostic Approach

For Neonates (<28 days):

• Median onset of bloody stools is 12 days after birth 1
• Preterm infants have later onset (median later than term), higher NEC incidence, lower exclusive breastfeeding rates 1
• Term infants presenting in first 1-3 days - strongly consider swallowed maternal blood, perform Apt test 2
• Well-appearing infant with isolated bloody stools - CMPA or FPIAP most likely, observational management without antibiotics is justified 3
• Ill-appearing infant with systemic signs - obtain abdominal radiograph for pneumatosis intestinalis (NEC), consider point-of-care ultrasound for pneumatosis, pneumoperitoneum, portal venous gas 7

For Infants and Children (>1 month):

• Obtain stool culture for Salmonella, Shigella, Campylobacter, Yersinia, C. difficile, and STEC when bloody diarrhea present with fever, abdominal tenderness, or signs of sepsis 5, 9, 8
• Test for Shiga toxin or genes encoding it - critical because STEC O157:H7 requires culture on sorbitol-MacConkey agar which is not routine 5
• Consider colonoscopy with biopsy if symptoms persist beyond 48 hours despite appropriate treatment or infectious workup is negative, to evaluate for inflammatory bowel disease 9

Critical Management Pitfalls to Avoid

NEVER give antibiotics for STEC O157:H7 or Shiga toxin 2-producing E. coli - this significantly increases risk of hemolytic uremic syndrome (HUS) 6, 9

NEVER use loperamide or antimotility agents in bloody diarrhea - increases risk of toxic megacolon, prolonged fever, and complications, especially in children under 18 years 9

Do NOT routinely give antibiotics for acute bloody diarrhea - only indicated for specific high-risk groups: infants <3 months with suspected bacterial etiology, bacillary dysentery (Shigella), recent international travelers with fever ≥38.5°C, immunocompromised children, and suspected enteric fever 6

When Surgery is Required

Only 1.7% of neonates with bloody stools require surgery - indications include stage III NEC with perforation (pneumoperitoneum), post-NEC stricture, and volvulus 1, 7