Abnormal Uterine Bleeding and Its Causes

Abnormal uterine bleeding (AUB) occurs when you experience bleeding outside the pattern of your regular menstrual cycle. This can mean light spotting or bleeding, or heavy bleeding along with shortness of breath, chest pain, and other symptoms that need immediate medical attention.

Episodes of abnormal uterine bleeding can be sudden (acute) and, rarely, life-threatening, but AUB also can be considered chronic with bleeding that keeps reoccurring across six months or more.

This article explains abnormal uterine bleeding causes and how they are diagnosed and treated. It will help you to know more about managing symptoms, when you should worry about AUB, and why it's important to see a healthcare provider.

What Is Abnormal Uterine Bleeding?

Abnormal uterine bleeding is a menstrual cycle disorder. Any bleeding that is outside of your regular cyclic menstruation is considered abnormal uterine 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.

Any change in the amount or duration of your period also is 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.

Symptoms of Abnormal Uterine Bleeding

Symptoms of abnormal uterine bleeding depend on an individual's menstrual cycle; what's considered a normal cycle can vary between 21 and 35 days. Four main variables describe menstruation:

• How much you bleed
• How many days you bleed
• How often you bleed
• How regular the intervals are between your periods

Changes in these patterns can mean heavier bleeding at normal period times, bleeding that occurs suddenly, or bleeding that begins to come and go more often when it's not your period. Other symptoms can include abdominal pain, as well as dizziness or other signs of blood loss.

Abnormal uterine bleeding that is heavy and/or frequent can also cause you to become anemic. Anemia caused by chronic blood loss makes you tired and weak.

With significant blood loss, you may experience shortness of breath and/or heart palpitations, fainting, or chest pain as your body tries to compensate for your anemia. This puts significant stress on your heart and can be very dangerous for you if you have ​underlying cardiovascular disease. 

Abnormal Uterine Bleeding Causes

Your healthcare provider will be able to determine the cause of your bleeding and can further classify abnormal bleeding as being due to structural and nonstructural causes. Examples include:

Structural causes (changes in your uterus):

• Polyps
• Adenomyosis
• Leiomyoma (fibroids)
• Endometrial hyperplasia (a precancerous condition) or cancer

Nonstructural causes: 

• Coagulopathy, abnormal bleeding due to an underlying bleeding condition
• Ovulatory dysfunction, abnormal bleeding because you are not ovulating regularly
• Endometrial bleeding because of an infection or other problem
• Iatrogenic, abnormal bleeding because of a medication you are taking
• Not yet specified, meaning 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

How Is Abnormal Uterine Bleeding Diagnosed?

What you report as changes in the amount, duration, frequency, and regularity of your periods is the information used by your healthcare provider to make the diagnosis of abnormal uterine bleeding.

Tests to diagnose the cause of your abnormal uterine bleeding include a pelvic exam and exam of the cervix. Your healthcare provider may order one of the following tests:

• Ultrasound exam—to make a picture of the pelvic organs.
• Hysteroscopy—to see the inside of the uterus.
• Endometrial biopsy—to examine the endometrium under a microscope
• Sonohysterography—to make images of the inside of the uterus
• Magnetic resonance imaging (MRI)—to create images of the internal organs
• Computed tomography (CT)—to show a cross-section of internal organs and structures

Blood tests also may be used to check hormone levels, thyroid function, and rule out blood diseases.

Abnormal Uterine Bleeding Treatment

Treatment for abnormal uterine bleeding will depend on factors including the severity of symptoms and the underlying cause of the bleeding. One study found that 88% of people who took oral contraceptives for acute AUB stopped bleeding in an average of three days. In other cases, surgery may be recommended.

AUB treatment interventions may include:

• Intravenous (IV) conjugated equine estrogen administration (like Premarin) to stop bleeding
• Antifibrinolytic drugs like Lysteda (tranexamic acid) to treat chronic AUB
• Nonsteroidal anti-inflammatory drugs
• Dilation and curettage (D&C) procedures

Some options can be used in specific situations, like the use of Desmopressin (DDAVP) in someone diagnosed with von Willebrand disease (a type of bleeding disorder). Or, a polyp removal might be necessary when an endometrial polyp is identified as the cause of AUB.

Summary

Abnormal uterine bleeding (AUB) is due to changes in your menstrual cycle that lead to heavy bleeding or bleeding between your normal period times. These symptoms can come on suddenly (and may need immediate care) or become part of a pattern that needs to be diagnosed by a healthcare provider.

A hormonal imbalance is the most common cause of AUB, but there are a range of conditions that can lead to abnormal uterine bleeding symptoms. Diagnosis is made through a physical exam and imaging or blood tests. In some cases, tissue samples may be needed.

Treatment will typically address the underlying cause of your abnormal uterine bleeding.