Final answer:
Dysfunctional uterine bleeding (DUB) is characterized by irregular or excessive uterine bleeding without evidence of organic lesions, often occurring during peri-menopause due to hormonal imbalances.
Step-by-step explanation:
The abnormal uterine bleeding due to the loss of coordinated hormonal changes without evidence of organic lesions is known as dysfunctional uterine bleeding (DUB). This condition often occurs during the peri-menopause phase of a woman's life, when the menstrual cycle becomes irregular but does not stop entirely. During this time, estrogen levels may still be nearly the same as before the transition, but the level of progesterone produced by the corpus luteum is reduced. This decline in progesterone can lead to abnormal growth or hyperplasia of the endometrium. However, the DUB is specifically characterized by an absence of the regular hormonal patterns and ovulation process, resulting in irregular or excessive bleeding without any underlying pathology such as fibroids or polyps.