GI Bleeding Causes in Baby
The short answer
Gastrointestinal bleeding in babies has many possible causes, most of which are benign. The most common cause of rectal bleeding is an anal fissure from constipation. Other causes include cow's milk protein allergy, infectious colitis, Meckel diverticulum, and intussusception. The color and amount of blood, along with associated symptoms, help determine the urgency and cause.
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By Age
What to expect by age
In newborns, bloody stool is most commonly from swallowed maternal blood, anal fissure, or cow's milk protein allergy. Necrotizing enterocolitis is a serious cause in premature infants. Any significant rectal bleeding in a young infant should be evaluated promptly.
Anal fissures and CMPA remain common causes. If blood is mixed with mucus in an otherwise well infant, CMPA is likely. If the baby is ill with fever and bloody diarrhea, infectious colitis should be considered. Intussusception, though more common after 6 months, can occur.
Intussusception (telescoping of the intestine) can present with intermittent severe abdominal pain, currant jelly stool (blood and mucus), and vomiting. This is a surgical emergency. Meckel diverticulum can cause painless, significant rectal bleeding. Infectious causes from stomach bugs are also common.
In toddlers, anal fissures from constipation remain the most common cause. Juvenile polyps can cause painless bright red rectal bleeding and are usually benign. Inflammatory bowel disease is rare at this age but should be considered with chronic bloody diarrhea and poor growth.
What Should You Do?
When to take action
- A small streak of bright red blood on a hard stool from an anal fissure in a constipated baby
- Any blood in your baby's stool should be reported to your pediatrician
- Recurrent small amounts of blood in stool
- Blood mixed with mucus in stool, especially in a young infant
- Large amounts of blood in stool or bloody diarrhea
- Currant jelly stool (dark red, mucousy) with intermittent severe pain and vomiting (possible intussusception)
- Black, tarry stool suggesting upper GI bleeding
- Any GI bleeding with pallor, rapid heart rate, or signs of shock
Sources
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Trust your instincts. If something feels wrong, reach out to your pediatrician.
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Related Digestive Concerns
Blood in Baby's Stool
Seeing blood in your baby's stool is understandably alarming, but the most common cause in young babies is a small anal fissure (a tiny tear from passing stool) or swallowed maternal blood from cracked nipples during breastfeeding. However, blood in stool always deserves medical evaluation to rule out less common but important causes like a cow's milk protein allergy or infection.
Blood Streaks in Baby's Stool
Bright red blood streaks on the surface of stool or on the diaper are most commonly caused by a small anal fissure (tear) from passing hard stools. This is very common and usually heals on its own when constipation is treated. Other causes include cow's milk protein allergy in young infants or minor rectal irritation. While usually benign, blood in stool should always be mentioned to your pediatrician.
Dark Blood in Baby's Stool
Dark or black blood in stool (melena) is different from bright red blood and may indicate bleeding from the upper digestive tract (stomach or upper intestine). In newborns, black stools in the first few days (meconium) are normal. Beyond the first week, dark, tarry, or coffee-ground-like material in stool needs prompt medical evaluation. Some dark-colored foods and iron supplements can also darken stools without being blood.
Signs of Intussusception in Babies
Intussusception is a serious but treatable condition where part of the intestine telescopes into itself, causing a blockage. The classic signs are sudden episodes of severe pain (baby screams and pulls legs up), vomiting, and eventually "currant jelly" stools (blood and mucus). It's most common between 6-18 months and requires immediate emergency care.
Meckel's Diverticulum Signs in Baby
Meckel diverticulum is a congenital outpouching of the small intestine present in about 2% of the population. Most people never know they have it. When symptomatic, it most commonly causes painless but significant rectal bleeding (usually dark red or maroon) in children under 2 years. It can also cause bowel obstruction or inflammation mimicking appendicitis.
My Baby's Belly Looks Swollen
A rounded, slightly protruding belly is completely normal in babies and toddlers due to immature abdominal muscles and their proportionally larger organs. However, if the belly becomes suddenly swollen, feels hard and tight, or is accompanied by pain, vomiting, or changes in bowel movements, it needs medical evaluation as it could signal gas buildup, constipation, or rarely, something more serious.