What is the cause of melena (black stool) in a newborn?

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Last updated: February 21, 2025View editorial policy

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Differential Diagnosis for Baby Poop Black

  • Single most likely diagnosis
    • Meconium: This is the most common cause of black stool in newborns, as meconium is the first stool of a newborn and is typically black or dark green in color. It is composed of waste materials that the baby ingested while in the womb.
  • Other Likely diagnoses
    • Blood in stool: Although less common than meconium, blood in the stool can cause it to appear black. This could be due to swallowed maternal blood during delivery or a gastrointestinal issue.
    • Iron supplementation: Iron supplements can cause black stools in infants, especially if they are taking high doses.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • Gastrointestinal bleeding: Although rare, gastrointestinal bleeding can cause black stools and is a life-threatening condition that requires immediate medical attention.
    • Intussusception: This is a condition where a part of the intestine telescopes into another part, causing bowel obstruction and potentially life-threatening complications. Black stools can be a sign of intussusception.
  • Rare diagnoses
    • Melanosis coli: A rare condition where the colon becomes discolored due to the accumulation of lipofuscin, a type of pigment. This can cause black stools, but it is extremely rare in infants.
    • Pseudomelanosis coli: A condition where the colon appears black due to the accumulation of pigment from certain medications or substances. This is also extremely rare in infants.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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