It can take a while for a girl's menstrual cycle to settle into something regular. Most of the time, if periods aren't regular it's because a girl's body is still developing. It might be confusing or annoying, but it's totally normal.

Sometimes, though, changes in blood flow can be a sign that something more serious might be going on.

What Is Dysfunctional Uterine Bleeding?

When a girl's period is irregular, doctors may diagnose her with something called dysfunctional uterine bleeding (DUB). DUB can cause periods that last longer or have more bleeding than normal.

DUB isn't usually a problem on its own. In fact, doctors often don't do anything to treat mild cases. But DUB can affect the health of some girls. The most common worry is that a girl might develop if she's bleeding more than she should.

What Causes It?

Most of the time, DUB happens because of changes in the body's hormone levels. For teen girls, one of the most common causes of hormonal changes is when the body doesn't release an egg from one of the ovaries. Doctors call this anovulation.

Anovulation is most likely to happen after a girl first starts getting her period because her ovaries aren't fully developed yet. It can last for several years until her periods become regular.

Normal Bleeding

In a normal menstrual cycle, the hormone estrogen signals the uterus to grow a lining of blood and tissue. The lining is the body's way of preparing for pregnancy: If an egg that gets released during is fertilized by sperm, it travels to the uterus and attaches to this cushiony lining. There it develops into a baby. If the egg isn't fertilized, this extra tissue leaves the uterus in the form of a period (menstruation).

To prevent the lining from building up too much, the hormone progesterone signals the body to stop the process.

Heavy Bleeding

If the body doesn't release an egg, it also doesn't make the progesterone needed to stop too much extra blood and tissue from building up. So when the lining is shed (or when it builds up so much that it just starts to fall apart), a girl can have more than normal amounts of bleeding. This heavier bleeding can happen either during her period or in between periods.

Besides adjusting to a normal cycle, other things can lead a girl to develop DUB. Some illnesses (like thyroid disease or polycystic ovary syndrome) can disrupt hormones. And problems like compulsive exercise, poor nutrition, or stress can cause hormone changes that may stop a girl from ovulating. Some severe cases of DUB are caused by bleeding disorders such as von Willebrand disease.

What Are the Signs?

Every woman has a heavy period from time to time. How do you know if it's dysfunctional uterine bleeding? Only a doctor can tell for sure, but there are some signs that bleeding might not be normal.

One thing that can alert you to problems is the 1-10-20 test:

• You use more than 1 sanitary pad or tampon per hour.
• Your period lasts more than 10 days.
• There have been fewer than 20 days between your periods.

If you notice any of these three things, call your doctor.

On the flip side, if your period stops for more than 3 months, talk to your doctor about that, too. Even if you're not bleeding, the lining of the uterus can continue to build up. Eventually it will need to flow out.

How Is DUB Diagnosed?

Hormones aren't the only cause of abnormal bleeding. So a doctor will want to rule out other health problems before deciding on a diagnosis of DUB. Sometimes, what may seem like DUB can be a clue that a girl has another health condition. For example, doctors sometimes find out that a girl with heavy periods has a bleeding disorder like von Willebrand disease.

To diagnose DUB, doctors will ask questions about things like periods and other bleeding problems. Expect your doctor to ask for the date of your last period.

A doctor also might ask questions that don't seem connected to bleeding — like about recent weight changes or if a girl has ever had sex. That's because conditions like polycystic ovary syndrome and some STDs can cause abnormal bleeding. If they're not treated, they may lead to more serious health issues, like infertility.

Girls who have had sex and miss a period need to see the doctor. Missed periods could be a sign of pregnancy as well as a sign of DUB. If you have heavy bleeding or bleeding between periods, it could be DUB, but an STD or a problem related to pregnancy also could be the cause. For example, an ectopic pregnancy (when a pregnancy implants someplace other than the uterus) can cause bleeding, and can be life threatening.

When DUB is suspected, the doctor probably will do a physical exam and possibly a pelvic exam. Sometimes doctors order blood tests or ultrasound exams to help find the cause of the symptoms. Blood tests also can indicate if a girl has anemia (fewer red blood cells than normal).

Treating DUB

Treatment will depend on the severity of DUB a girl has, which is determined by levels (which doctors use to diagnose anemia):

• Mild cases = a hemoglobin level of 12 or higher. A girl with a mild case of DUB is not considered anemic, and her doctor probably will tell her to keep track of her periods for a couple of months. The doctor might recommend ibuprofen or another nonsteroidal anti-inflammatory drug (NSAID) to decrease blood loss and ease pain from cramps. The doctor also might suggest taking a multivitamin with iron.
• Moderate cases = a hemoglobin level between 10 and 12. Girls with this hemoglobin level are anemic, so doctors usually recommend hormonal treatment, most often in the form of birth control pills. Doctors usually tell them to take the pills multiple times a day in the beginning and then taper down to kick the menstrual cycle back into gear. A girl also will be given iron pills.
• Severe cases = a hemoglobin level below 10. Someone with a severe case bleeds heavily and may faint, feel dizzy, look pale, and have low blood pressure or a high heart rate. In severe cases, a girl might be hospitalized and given a blood transfusion. Most cases of DUB are not severe. A high percentage of severe cases involve an underlying bleeding disorder.

Most girls just need time for their bodies to adjust to their hormones during their teens, and eventually their menstrual cycles get regular naturally. If you have any concerns that your period might not be normal, talk to your doctor.

Reviewed by: Nadia Dowshen-Atanda, MD
Date reviewed: June 2011