Endometriosis occurs when the endometrial-like cells that normally line your uterus grow in other parts of your pelvis, such as your ovaries or fallopian tubes. Depending on wear the cells grow, you’ll experience different symptoms.

Bladder endometriosis is a rare form of the condition. It occurs when endometrial-like cells grow inside or on the surface of your bladder.

Each month during your menstrual cycle, endometrial-like cells build up. The tissue in your uterus is then shed from your body. But when it’s on the outside wall of your bladder, the tissue has nowhere to go.

According to a 2014 case report on the condition, up to 5 percent of women who have endometriosis have it in their urinary system. The bladder is the urinary organ most often affected. The ureters — the tubes urine travels through from the kidneys to the bladder — may also be involved.

There are two types of bladder endometriosis. If it occurs on the bladder surface only, it’s known as superficial endometriosis. If the tissue has reached the bladder lining or wall, it’s known as deep endometriosis.

According to a 2012 review of bladder endometriosis, about 30 percent of women who have it don’t experience any symptoms. Their doctor may find the condition when testing for another type of endometriosis, or for infertility.

If symptoms do appear, it’s often around the time of your period. Symptoms may include:

If endometriosis is in other parts of your pelvis, you may also experience:

Doctors don’t know exactly what causes bladder endometriosis. A few possible theories are:

  • Retrograde menstruation. During menstrual periods, blood may flow backward through the fallopian tubes and into the pelvis instead of out of the body. Those cells then implant in the bladder wall.
  • Early cell transformation. Cells left over from the embryo may develop into endometrial-like cells.
  • Surgery. Endometrial cells may spread to the bladder during pelvic surgery, such as during a cesarean delivery or hysterectomy. This form of the disease is called secondary bladder endometriosis.
  • Hematogenous/lymphatic spread. Endometrial-like cells may travel through the lymph system or blood to the bladder.
  • Genes. Endometriosis sometimes runs in families.

Endometriosis affects people during their reproductive years. The average age when women receive a diagnosis of bladder endometriosis is 35 years.

Your doctor will start by doing a physical exam. They’ll check your vagina and bladder for any growths. You may have a urine test to look for blood in your urine.

These tests can help your doctor diagnose bladder endometriosis:

  • Ultrasound. This test uses high-frequency sound waves to create pictures from inside your body. A device called a transducer is placed on your belly (transabdominal ultrasound) or inside your vagina (transvaginal ultrasound). An ultrasound can show the size and location of the endometriosis.
  • MRI scan. This test uses powerful magnets and radio waves to look for endometriosis in your bladder. It can also find the disease in other parts of your pelvis.
  • Cystoscopy. During this test, your doctor inserts a scope through your urethra to view your bladder lining and check for endometriosis.

Endometriosis is divided into stages based on the amount of tissue you have and how deeply it extends into your organs.

The stages are:

  • Stage 1. Minimal. There are small patches of endometriosis on or around organs in the pelvis.
  • Stage 2. Mild. The patches are more extensive than in stage 1, but they’re not yet inside the pelvic organs.
  • Stage 3. Moderate. Endometriosis is more widespread. It’s starting to get inside organs in the pelvis.
  • Stage 4. Severe. Endometriosis has penetrated many organs in the pelvis.

Endometriosis can’t be cured, but medication and surgery can help manage your symptoms. Which treatment you receive depends on how severe your endometriosis is and where it’s located.

Surgery

Surgery is a possible treatment for bladder endometriosis. Removing all of the endometrial-like cells can relieve pain and improve your quality of life.

The surgery can be done in a couple of different ways. These are specific to treating the bladder endometriosis. Other areas may also need to be targeted.

  • Transurethral surgery. The surgeon places a thin scope into your urethra and bladder. A cutting tool at the end of the scope is used to remove the endometrial-like cells.
  • Partial cystectomy. The surgeon removes the part of your bladder that contains the abnormal tissue. This procedure can be done through one large incision, called a laparotomy, or several small incisions, called a laparoscopy, in the abdomen.

You may have a catheter placed in your bladder after the surgery. The catheter will remove urine from your body while your bladder heals.

Medication

Hormone therapy slows the growth of endometrial-like cells. It can also relieve pain and help preserve your fertility.

Hormonal treatments include:

Without treatment, bladder endometriosis could cause kidney damage. Having surgery can prevent this complication.

Very rarely, cancer can grow from endometrial-like cells in your bladder.

Bladder endometriosis doesn’t directly affect your fertility. However, if you also have endometriosis in your ovaries or other parts of your reproductive system, you may have a harder time getting pregnant. Having surgery may increase your odds of conceiving.

Your outlook depends on how severe your endometriosis is and how it’s treated.

Surgery can often relieve symptoms. However, some research indicates that in up to 25 percent of women, endometriosis comes back after surgery, so you may require further surgery.

Endometriosis is a chronic condition that can affect your day-to-day life. But with a treatment plan from your doctor and help from friends, family, or local support groups, it can be managed.

To find support in your area, visit the Endometriosis Foundation of America or the Endometriosis Association.