Postpartum constipation what is the cause of black stool?

Postpartum constipation black stool may be caused by long time no defecation caused by stool blackening, or due to eating pork liver, pig blood and other foods, may also be induced by gastrointestinal bleeding, should be admitted to hospital for blood routine and gastroscopy. Suggestions: usually should eat more vitamins and fiber-rich foods, clean gastrointestinal tract, keep stool unobstructed.