Abnormal uterine bleeding (AUB) is a common yet sometimes alarming condition experienced by many women. It refers to any unusual bleeding from the uterus that deviates from normal menstrual cycles, either in volume, duration, or timing. While it can be benign, it’s essential to recognize when AUB might signal a more serious underlying issue.

Keep reading to learn more about the causes, symptoms, and appropriate times to seek medical attention for AUB.

Understanding regular menstrual cycles

Before discussing abnormalities, it’s crucial to understand what constitutes a normal menstrual cycle. Typically, a menstrual cycle lasts between 24 to 38 days with bleeding lasting about 2 to 8 days. The amount of blood loss averages 30 to 40 milliliters per cycle, or roughly equivalent to 2 to 3 tablespoons, but may be as much as 80mL per cycle. Variations are normal, but significant deviations can indicate a problem.

Types of Abnormal Uterine Bleeding

AUB encompasses several types of irregular bleeding:

Heavy Menstrual Bleeding 

Heavy menstrual bleeding (HMB) is characterized by bleeding exceeding 80 milliliters per cycle and interfering with a woman’s capacity to perform her usual activities.

Intermenstrual bleeding

Intermenstrual bleeding (IMB) is defined as bleeding occurring beyond the maximum normal 8-day duration of menses, or occurring at other times in the cycle in between regular menstrual bleeding.


Oligomenorrhea is an older term used to describe infrequent menses, typically with intervals lasting longer than 38 days.


Frequent periods, occurring less than 24 days apart but with a regular volume of blood flow.

Postmenopausal bleeding

Any bleeding occurring more than 12 calendar months after complete cessation of menses, or menopause.

Common causes of Abnormal Uterine Bleeding

Hormonal imbalances

The most frequent cause, often due to PCOS, thyroid disorders, or perimenopause.

Uterine fibroids (Myomas)

Noncancerous abnormal growths in the uterus that can cause heavy or prolonged bleeding.


Blood-vessel filled outgrowths on the lining of the inner wall of the uterus or cervix.


A condition where tissue similar to the uterine lining grows outside the uterine lining, causing pain and bleeding.


A form of endometriosis where the tissue of the uterine lining (endometrium) is implanted into the muscular wall of the uterus.


Certain drugs, like blood thinners and hormonal contraceptives, can affect menstrual bleeding.

Pregnancy complications

Miscarriage, ectopic pregnancy, or other pregnancy-related issues can cause abnormal bleeding.


Cervical, uterine, or ovarian cancer can present with abnormal bleeding in women of any age group.


Reproductive tract infections, especially pelvic inflammatory disease, may cause irregular bleeding patterns.

When to be concerned about Abnormal Uterine Bleeding

While occasional irregular bleeding might not warrant immediate concern, certain symptoms should prompt a visit to a healthcare provider:

Heavy bleeding

Bleeding amounting to more than 80mL per menstrual period, needing to change sanitary products every one to two hours, passing large clots, or experiencing symptoms of anemia (fatigue, dizziness).

Bleeding after menopause

Any postmenopausal bleeding should be investigated, as it can be a sign of endometrial cancer.

Prolonged bleeding

Bleeding that lasts more than 8 days consistently.

Frequent bleeding

Menstrual cycles shorter than 24 days.

Intermenstrual bleeding

Bleeding between periods or after sex.

Painful bleeding

Severe cramping or pain during periods, which may indicate conditions like endometriosis or fibroids/myomas.

Symptoms of infection

Vaginal discharge with an unusual appearance or odor, ulcerations on the vulvar or vaginal skin, and swollen lymph nodes along the groin may indicate the presence of reproductive tract infections, which may also result in irregular bleeding patterns.

Diagnostic process

If you experience any concerning symptoms, a healthcare provider will typically start with a detailed medical history and physical examination, including a vaginal and pelvic examination. Further diagnostic tests may include:

Blood tests

To check for anemia, thyroid function, and hormone levels.

Pelvic ultrasound

To visualize the uterus, ovaries, and other pelvic structures.

Endometrial biopsy

Sampling the uterine lining to check for cancer or other abnormalities.

Book an OBGYN appointment today

In conclusion, consulting with an OBGYN for abnormal uterine bleeding is a crucial step towards understanding and addressing this potentially concerning symptom. Regardless of the cause of AUB, early intervention not only alleviates symptoms and improves quality of life but also prevents potential complications. Therefore, seeking professional medical advice ensures optimal care and peace of mind. Book your OBGYN consults and PCOS packages today on mykindred.co!

Last medically reviewed on May 30, 2024.