Uterine bleeding may be caused because of weakness of the thoroughfare and conception vessels due to impairment of yin-collaterals by internal activation of yang-qi during ovulation resulting from weak constitution, deficiency of kidney-essence, or early marriage, excessive sexual intercourse, multiparity, or dysphoria, rage, deficiency of kidney-yin and failure of yin to coordinate with yang due to consumption of kidneyyin by intense kidney-fire.

It may be caused by invasion of damp-heat due to improper care during menstruation and after delivery. Or it may be caused by accumulation of damp-heat into the uterine collaterals, thoroughfare and conception vessels due to failure of the spleen to transform and transport nutrients that generates dampness and heat. Or it may be caused by blockage of the uterine collaterals due to retention of menses and blood stasis after delivery. Or it may be caused by qi stagnation and blood stasis due to depression.