Abnormal Bleeding

Abnormal uterine bleeding is a menstrual cycle disorder. Any bleeding that is outside of your regular cyclic menstruation is considered abnormal uterine bleeding. Any change in the amount or duration of your period is also considered abnormal uterine bleeding. Abnormal uterine bleeding can range from a random day of light spotting to 10 days of heavy bleeding replacing your normal menstrual flow.

During your reproductive years, it is likely that you will experience some type of abnormal uterine bleeding at least once. Abnormal uterine bleeding that occurs only once usually does not indicate any significant underlying problem. 


If you have 3 consecutive months of abnormal bleeding it is more likely that you have an underlying problem causing the bleeding. If you are just starting to menstruate or if you are in the last few years of your regular menstrual cycles or perimenopausal, you are at an increased risk of experiencing abnormal uterine bleeding.

  • Abnormal uterine bleeding with heavy menstrual bleeding (AUB/HMB)
  • Abnormal uterine bleeding with bleeding between periods (AUB/IMB)

Structural causes (changes in your uterus):

  • Polyps (AUB-P)
  • Adenomyosis (AUB-A)
  • Leiomyoma (AUB-L)
  • Malignancy and hyperplasia (AUB-M)

Nonstructural causes: 

  • Coagulopathy (AUB-C)—abnormal bleeding due to an underlying bleeding condition
  • Ovulatory dysfunction (AUB-O)—abnormal bleeding because you are not ovulating regularly
  • Endometrial (AUB-E)—abnormal bleeding because of a problem with the lining of your uterus like an infection
  • Iatrogenic (AUB-I)—abnormal bleeding because of a medication you are taking
  • Not yet specified (AUB-N)—your healthcare provider can’t find an underlying reason for your abnormal bleeding

Other causes:

  • Birth control methods (intrauterine device (IUD) or birth control pills)
  • Miscarriage or ectopic pregnancy

Vaginal bleeding between periods is one symptom of abnormal uterine bleeding. Having extremely heavy bleeding during your period can also be considered abnormal uterine bleeding. Very heavy bleeding during a period and/or bleeding that lasts more than 7 days is called menorrhagia. For example, women may bleed enough to soak through 1 or more tampons or sanitary pads every hour.

Gynaecology Services