You've probably heard of pelvic inflammatory disease (PID), but what is it exactly? It's a bacterial (or sometimes fungal or parasitical) infection that causes inflammation to the female upper reproductive tract - most commonly the fallopian tubes, ovaries and uterus. It's not a condition that gets mentioned frequently, but the Centers for Disease Control (CDC) estimates that up to 750,000 women are diagnosed with PID every year. And getting it can be a big deal: PID can damage the fallopian tubes and tissues around the uterus and ovaries, causing serious consequences such as infertility, ectopic pregnancy, abscesses and chronic pain in the pelvic area. Plus, because it's often a side effect of sexually transmitted infections (STIs) such as chlamydia and gonorrhea, it can be a sign that you've been infected.

Unfortunately, many women have never heard of PID. Here are a few things worth knowing.

It is most frequently caused by STIs

No one wants to discuss having having an STI, and many people don't even realize they have one. But if you're sexually active, you should get tested because the most common cause of pelvic inflammatory disease is chlamydia, followed by gonorrhea. These two common bacterial STDs often come without symptoms. Fortunately, they, like PID, can be easily treated with a course of antibiotics. (The testing isn't that bad, promise! Read more in Scared of STD Tests? Here's Why You Shouldn't Be.)

Childbirth, miscarriage, abortion, surgery and an IUD can also cause PID

Anything that touches your cervix has the potential to let in bacteria, parasites and fungal infections, all of which can cause pelvic inflammatory disease.

You may be treated as if you and/or your partner have an STI

If you're diagnosed with PID, you will be treated with antibiotics. Your doctor may also prescribe them to your partner as a precautionary measure. Don't be offended. Untreated STIs are the leading cause of PID, so many doctors feel that it's better to be safe than sorry and treat both partners when possible. Yes, this is awkward when telling said partner. Yes, you should do it anyway. (Communication is a form of protection. Learn more in Be a Sexy Safer Sex Superhero in 6 Steps.)

PID is a common condition

It is estimated that more than 750,000 women in the U.S. have an episode of acute PID each year. Exact numbers for the total number of infections can be difficult to determine as PID has few symptoms, and often goes undiagnosed.

PID is the leading cause of infertility in young women (under 25)

The inflammation caused by PID causes the formation of adhesions (scar tissue) in the fallopian tubes, ovaries and uterus. This scar tissue can eventually block the fallopian tubes, preventing eggs from passing through. It is also a major factor in causing ectopic pregnancies. Getting treated for PID early reduces the likelihood of fertility problems.

PID can lead to chronic pelvic pain

Left untreated, or even treated late, PID can cause chronic pelvic pain. This can manifest as severe pain during intercourse and/or pain in the lower abdomen (which can also be quite severe).

The pain changes in severity depending on the time of the month

During ovulation, scar tissue becomes easily inflamed, which increases pain during intercourse. If you have PID, you might want to avoid penetration during that particular time of the month, or find positions that don't hurt as much.

No pain does not mean no problem

Depending on the cause of PID, you may have different symptoms. PID caused by chlamydia is normally asymptomatic, which means that many women only discover they have it when they seek treatment for infertility. However, you may find that you have symptoms such as:

  • Higher-than-normal body temperature.
  • Fatigue
  • Irregular periods
  • Lower back pain
  • Rectal pain
  • Unusual vaginal discharge
  • Vomiting

Nobody likes visiting the gynecologist, and with many of the symptoms you might not even think you need to. But irregular periods and unusual vaginal discharge should always be looked into. Lower back pain is a frequent symptom of many gynecological conditions as well.

PID can cause abscesses

An abscess is essentially an infected sore, and in PID, this can occur on the lips at the entrance of the vagina (known as Bartholin's cysts), as well as in the fallopian tubes and ovaries. This is normally treated with antibiotics. If the abscess does not respond to antibiotics, it may require surgery to drain it safely. It is vital that abscesses inside the pelvis be treated or removed as soon as possible, because they are potentially life threatening if they burst.

If you've had it once, you are likely to have it again

Sad but true: Women often experience repeated episodes of PID. The more often you get PID, the more likely you are to get it again in the future. The condition tends to return if the initial infection is not totally cured (which is why it is very important to complete a course of antibiotics), or because a sexual partner has not been tested and treated for STIs (another very important conversation to have).

Even if your partners are STI-free and you've completed your course of antibiotics, if the first episode of PID has damaged your cervix, it becomes easier for bacteria to move into your reproductive tract, putting you at risk for developing the condition again. Repeated episodes of PID are correlated with an increased risk of infertility.

Using condoms and getting tested for STIs can help prevent PID

PID isn't always caused by STIs, but contracting an STI is the most preventable cause of the disease. Practicing safer sex and eliminating these most common culprits will increase your chances of avoiding PID. Plus, safer sex is sexy sex. And there's nothing sexier than taking good care of the your body and your health.