Delayed menstruation after breast nodule surgery may be caused by mental tension, or it may be caused by the use of medication after the operation, and the thinner endometrium may also cause the same symptoms. 1. Mental tension: Emotions have a great influence on menstruation. Emotions affect the secretion function of the ovaries, pituitary gland and other endocrine organs, thus affecting the menstrual cycle. So tension and relatively high stress can easily lead to delayed menstruation. 2. Drugs: The drugs you need to take after breast nodule surgery can cause endocrine disruption, which can lead to delayed menstruation. 3. Thin uterine lining: As the uterine lining of a woman is thin, it is not able to shed to form menstruation, so she may not be able to have menstruation at this time. It is recommended that patients who have delayed menstruation after breast nodule surgery should go to regular hospitals to do hormone six and gynecological examination, and listen to the doctor’s advice and active treatment.