Friday, November 14, 2014

Pediatrics: There's blood in the stool!

Clinical Scenario:
A 2 week old child presented to the emergency department with blood in the stool.  The child was otherwise well, tolerating feeds, no apparent abdominal pain, no abdominal distension, no fever.  Other than the dark red blood, the stool appeared about the same.  Child was born via vaginal delivery following an uncomplicated 40 week pregnancy.  Had stool within minutes of birth and has had normal stooling since.

Clinical Question:
What should be considered in a neonate/infant presenting with bloody stool?

Differential Diagnosis (DDx) of bloody stool in neonate:
-Swallowed maternal blood
-Anorectal fissure
-Necrotizing enterocolitis (NEC)
-Malrotation with midgut volvulus
-Hirschsprung disease
-Food protein-induced proctitis/colitis (not to be confused with similar food protein-induced enterocolitis syndrome [FPIES] where child is usually sicker and involves vomiting)

Other Differentials in later infancy:
-Intussusception (more common between 6-36 months of age, 60% before 1 year, 80% before 2 years)
-Infectious colitis – rare during neonate period given reduced exposure
-Meckels direrticulum – rare cause of bleeding in neonatal period

Several of the DDxs listed above could be excluded after review of the history and physical exam. Physical exam in this patient excluded anorectal fissure.  The child was 2 weeks old, making persistent swallowed maternal blood highly improbable.  As the patient was a well appearing neonate NEC and malrotation were also unlikely.  Normal stooling made Hirschsprung less likely.  Her age made intussusception, infectious colitis, and Meckels less likely.  This left food protein allergy, most commonly due to cows milk.  But there was a problem: I remembered asking the mother about the child’s diet, and she had reported that the infant was exclusively breastfed.  How could cows milk be a causal factor in a breast fed infant?

Literature review: 
As it turns out, many of the proteins consumed by mothers are passed onto their infants and can cause food protein-induced proctitis/colitis in which the only symptom in infants under 2 months of age is blood in the stool.  A small study of 95 breastfed infants presenting with only bloody stool found that elimination of specific proteins in the maternal diet or through use of extensively hydrolyzed casein-based formula resolved the bleeding within 72 to 96 hours.  65% of the infants were found to be sensitive to cows milk, 19% to egg, 6% to corn, and 3% to soy.  This proctitis/colitis, as the name implies, only induces an inflammatory response in the rectum and distal sigmoid colon.  At least half of the infants manifesting this condition are breast fed.  The symptoms will usually resolve by one year of age with the elimination of the offending protein, and most of these children can go on an unrestricted diet with no further problems.  Interestingly, this reaction does not appear to be IgE-mediated, so routine food allergy testing is not recommended.

Take home points:
-With blood in stool, must have wide differential
-If child otherwise well, with other dangerous conditions ruled out, can send stool culture and discharge home with trial of elimination of most common offending agents
-Most common agent is cow's milk, even if the only source is through the mother's breast milk

References:
1. Lake AM. Food-induced eosinophilic proctocolitis. J Pediatr Gastroenterol Nutr 2000;30 Suppl:S58
2. Odze RD, Wershil BR, Leichtner AM, Antonioli DA. Allergic colitis in infants. Journal of Pediatrics 1995;126(2):163-170.

Submitted by Steven Hung (@DocHungER), PGY-2
Faculty reviewed by Joan Noelker

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