Although hemorrhoids are not fully understood, they are thought to occur when the connective tissues within the anal cushion weaken, allowing the blood vessels in the region to become enlarged and displaced.
Generally, hemorrhoids are associated with conditions that increase pressure in the abdomen or create a shear force against the anal cushions, such as:[1][2][3][4]
- Constipation (either from hard or lumpy stool or straining during bowel movements)
- Pregnancy and vaginal delivery
- Chronic diarrhea
- Cirrhosis with ascites (fluid in the abdominal cavity)
- Obesity
- Anal intercourse
- Pelvic floor dysfunction