What is happening when I have a bowel movement and bleed from my rectum painlessly even though am not constipated.?

There are a few possible causes of painless rectal bleeding during a bowel movement, even in the absence of constipation. Here are a few common reasons:

1. Hemorrhoids: Hemorrhoids are swollen and enlarged veins in the rectum or anus. They can cause painless bleeding, especially after a bowel movement. Hemorrhoids are common and usually not serious, but they can be uncomfortable and may require treatment if they become severe.

2. Anal fissures: Anal fissures are small tears in the skin around the anus. They can cause sharp, burning, or stinging pain during a bowel movement, but sometimes the pain may be minimal. Fissures can also cause painless bleeding.

3. Diverticular disease: Diverticular disease is a condition where small pouches develop in the colon. These pouches can sometimes bleed painlessly, especially after a bowel movement. Diverticular disease is common in older adults.

4. Inflammatory bowel disease (IBD): IBD is a group of conditions that cause inflammation and ulcers in the digestive tract. Crohn's disease and ulcerative colitis are two types of IBD. Both can cause rectal bleeding, which may or may not be associated with pain.

5. Colorectal polyps or cancer: Colorectal polyps are growths on the lining of the colon or rectum. Most polyps are benign, but some can develop into cancer. Colorectal cancer can also cause painless rectal bleeding, especially in the early stages.

If you are experiencing painless rectal bleeding, it's important to see a doctor to determine the cause and get appropriate treatment. The doctor may recommend a variety of tests, such as a colonoscopy, to diagnose the underlying condition.