What is a drop of dark red blood on the surface of stool?

A drop of dark red blood on the surface of stool may be caused by hemorrhoids, anal fissure, ulcerative colitis and other diseases.

1. Hemorrhoids

are caused by venous dilation at the lower end of the rectum or around the anus. When the patient defecates, the hemorrhoids are ruptured due to friction, which will lead to blood outflow and red stool surface.

2. Anal

fissure is formed by tearing the entire skin of the anal canal. There will be a small amount of blood outflow from the anus, showing dark red blood staining the stool surface.

3. Ulcerative colitis

is a chronic colitis, mainly involving the colon mucosa. It can lead to ulcers and bleeding of the colon mucosa, resulting in dark red blood in the stool.