What causes Abnormal Menstrual Bleeding?

Abnormal menstrual bleeding or abnormal uterine bleeding (AUB) is defined as bleeding from the uterus that is irregular, prolonged, heavy or occurs after sexual intercourse or after menopause.

The normal menstrual cycle usually occurs between 21 to 35 days and the duration is between 3 to 7 days.

For instance, your periods may last more a week, may require you to change your pads every hour even during the night, or it may even occur in between your cycles. Post-menopausal bleeding or post-coital bleed are often abnormal and should be investigated.

What are the causes of abnormal uterine bleeding?

It is important to rule out non-gynaecological causes as appropriate treatment can be recommended as early as possible. Some of these causes include thyroid problems, coagulation problems, and liver conditions. Some of the symptoms may include easy bleeding and bruising.

Other causes may include medications such as anticoagulants and hormones as well as intrauterine devices (IUDs). Sometimes it may be due to a miscarriage or ectopic pregnancy.

Gynaecological causes include growths like polyps and fibroids, endometriosis, adenomyosis, as well as cancerous tumours.

Endometriosis is a condition where the lining of the uterus grows outside of the uterus, while adenomyosis occurs when the lining of the womb grows into the muscular walls of the womb. They usually present with menstrual cramps; for adenomyosis, a boggy uterus may be felt on clinical examination. Otherwise, these causes may not present with any symptoms. Therefore, they are usually confirmed via radiological investigations, which may include an ultrasound or CT scan. Sometimes a type of surgery called a hysteroscopy, a procedure where a small camera is inserted through your vagina into your uterus, is required to visualise the inner lining of your womb and obtain biopsies.

For young women, it is also important to note that a common cause of abnormal vaginal bleeding may be a symptom of a sexually transmitted disease (STD). Please refer to this article on common symptoms of STDs.


The first-line treatments may include non-hormonal treatments such as NSAIDs, or hormonal treatments such as combined oral contraceptive pills, oral progesterone, GnRH analogues and progesterone implants. You may also be given tranexamic acid. Most of these treatments will help reduce the amount of bleeding and some of them may even reduce the size of the fibroids. Some of these treatments have a contraceptive effect and have varying duration, so please refer to these articles (Part I and Part II) on the types of contraceptives available.

Second-line treatments include surgical removal of these growths, endometrial ablation (which thins out the lining of the womb) and uterine artery embolisation (which blocks the blood supply to the womb).

The definitive treatment, which is also irreversible, will be a hysterectomy, which is the removal of the womb.

Lastly, when in doubt, please consult a doctor especially if you feel that you are experiencing these symptoms.