Haemorrhoids
Engorgement and downward displacement of the normal vascular anal cushions that help maintain continence, so bleeding is bright and painless because the cushions themselves have no somatic sensory innervation above the dentate line.
First principles
Haemorrhoids are engorged normal anatomy, not new growths
Everyone has anal cushions: submucosal vascular tissue arranged at the 3, 7 and 11 o'clock positions above the dentate line, which contribute to fine continence by helping seal the anal canal. Raised intra-abdominal or intra-anal pressure, from straining against constipation, prolonged sitting, pregnancy or chronic coughing, engorges these cushions with venous blood and stretches their supporting connective tissue, so they enlarge and gradually slide distally. Haemorrhoids are therefore this same tissue made pathological by pressure and prolapse, not an abnormal structure appearing from nowhere.
Educational content pending clinical review. Not medical advice.