Of the following, which is the most likely cause of hemodynamically significant lower gastrointestinal bleeding in a 6 month old male child?

a. Meckel diverticulum

c. Intussusception

All of the choices are possible causes of lower GI bleeding in a 6 month old; intussusception and a bleeding Meckel diverticulum are the most common. Upper GI hemorrhage with passage of blood distal should also be considered, but is not discussed further here as sampling nasogastric aspirate is a relatively easy and reliable means of differentiating these problems. The magnitude of blood loss associated with intussusception is usually minor, but the associated vomiting and bowel obstruction may lead to significant volume depletion with hemoconcentration. The magnitude of the hemorrhage is usually more significant with a Meckel diverticulum.

Infectious diarrheas also occur in this age group. Typically, signs and symptoms include fever and ileus with bloody diarrhea. The diagnosis is confirmed with stool examination for leukocytes and cultures for specific pathogens.