Uterus

What is a uterus?

Your uterus is a pear-shaped organ in the reproductive system of people assigned female at birth (AFAB). It’s where a fertilized egg implants during pregnancy and where your baby develops until birth. It’s also responsible for your menstrual cycle.

What does a uterus do?

Your uterus plays a key role in your reproductive health and function. The three main jobs of your uterus are:

• Pregnancy: Your uterus stretches to grow your baby during pregnancy. It can also contract to help push your baby out of your vagina.
• Fertility: Your uterus is where a fertilized egg implants during conception and where your baby grows.
• Menstrual cycle: Your uterine lining is where blood and tissue come from during menstruation.

What happens to your uterus during menstruation?

During your menstrual cycle, the lining of your uterus goes through several changes. The lining (called the endometrial lining) gets thicker and rich with blood as you near ovulation (releasing an egg from the ovaries). If an egg is fertilized during that cycle, it implants into the lining of your uterus, and pregnancy begins.

Your endometrial lining sheds if pregnancy doesn’t happen (this is your period). This process repeats every menstrual cycle unless pregnancy occurs.

What happens to your uterus during pregnancy?

If conception (when the egg is fertilized by sperm) occurs during your menstrual cycle, the fertilized egg implants into your uterine lining. The fertilized egg (called a blastocyte) burrows into the endometrial lining of your uterus (implantation). This is when pregnancy officially begins, and you miss your menstrual period.

Your uterus grows and stretches like a balloon to accommodate your growing baby. It contracts during labor and delivery to help push your baby out of your vagina. After about six weeks, your uterus returns to its pre-pregnancy size (although, it can be slightly larger and show signs of being stretched).

What does a uterus look like?

Your uterus looks like a light bulb. It’s about the size of your fist. It’s also commonly described as an upside-down pear. Your uterus has two horn-like organs at the top (the fallopian tubes). It connects to your cervix at the bottom, which is the part that opens (dilates) during vaginal delivery.

Your uterus has several sections:

• Fundus: The uppermost and widest part of your uterus. It connects to your fallopian tubes.
• Corpus: The main body of your uterus. This is where a fertilized egg implants during pregnancy.
• Isthmus: The part of your uterus between your corpus and cervix. It’s where your uterus starts to narrow or thin.
• Cervix: The lowest part of your uterus. Your cervix opens to your vagina.

Where is the uterus in your body?

Your uterus is in your pelvis between your bladder and rectum. It’s supported by your pelvic floor muscles and perineal body. Ligaments in your pelvis, lower back and hips also help hold your uterus in place.

What is your uterus made of?

Your uterus consists of three layers:

• Perimetrium: The outermost, protective layer.
• Myometrium: The highly muscular middle layer. This is what expands during pregnancy and contracts to push your baby out.
• Endometrium: The inner layer or lining of your uterus (uterine lining). This layer of your uterus is shed during your menstrual cycle.

How big is your uterus?

Your uterus is about 3 inches from top to bottom and 2 inches wide at the widest part. It’s about 1 inch thick and weighs around 1 ounce.

How big is your uterus during pregnancy?

Your uterus is one of the most unique organs in your body. It can stretch from the size of a lemon to the size of a watermelon during pregnancy. Your uterus can be up to 2 pounds when your baby is born. Your uterus shrinks down to its normal size (a process called involution) and position about six weeks postpartum (after giving birth).

What are the positions of the uterus?

Your uterus can lie in several positions. A typical uterus tilts forward at your cervix and points towards your abdomen. This is called an anteverted uterus. Most people have an anteverted uterus.

If you don’t have an anteverted uterus, you might have a:

• Retroverted uterus: Commonly called a tipped or tilted uterus. This is when your uterus is tilted or tipped backward so it curves toward your spine instead of forward toward your abdomen.
• Anteflexed uterus: Your uterus is anteflexed when it’s bent forward. The tilt is severe and can put pressure on your abdomen or bladder and cause painful symptoms.
• Retroflexed uterus: Your uterus is retroflexed when it’s bent backward. The tilt puts pressure on your lower back.

Some people never know they have an irregular-shaped uterus because they don’t have symptoms. In some cases, you’ll have symptoms that require treatment by your healthcare provider.

What are the common conditions of the uterus?

Several health conditions can be associated with your uterus. Some of the most common conditions are:

• Uterine fibroids: Small, noncancerous tumors in your uterus.
• Uterine polyps: Growths in the endometrial lining of your uterus.
• Uterine cancer: Cancer of your uterus, such as endometrial cancer or uterine sarcoma.
• Endometriosis: A condition when your uterine lining grows in places other than your uterus.
• Pelvic inflammatory disease: An infection of your reproductive organs.
• Uterine prolapse: A condition where your uterus slips out of position.
• Infertility: The inability to get pregnant.

What are common symptoms of uterine conditions?

If you’re experiencing issues with your uterus, your symptoms might include:

• Problems with your menstrual cycle.
• Irregular bleeding.
• Pelvic pain.
• Irregular vaginal discharge.
• Difficulty getting pregnant.
• Painful urination (dysuria).

What are the types of uterine abnormalities?

Two ducts (called the Mullerian ducts) fuse together to form one uterine cavity during normal fetal development. For some people, these ducts don’t fuse properly, resulting in an irregularly-shaped uterus. Uterine abnormalities are congenital, meaning you were born with them.

Some of the most common abnormalities are:

• Bicornuate uterus: A heart-shaped uterus.
• Arcuate uterus: Similar to a bicornuate uterus but with less of a dip or heart shape.
• Septate uterus: When your uterus is divided into two parts by a membrane.
• Unicornuate uterus: When you have one fallopian tube and an irregularly shaped uterus.
• Didelphys uterus: When you’re born with two uteruses.

What tests diagnose conditions of the uterus?

There are several reasons your healthcare provider may need to use diagnostic tools on your uterus. Some of these reasons include screening for cancer, monitoring pregnancy, helping with fertility issues or diagnosing conditions.

Some of the most common tests involving your uterus are:

• Pelvic exam: When your healthcare provider looks at your uterus, cervix, vagina, ovaries and other reproductive organs.
• Ultrasound: Uses sound waves to create a picture of the inside of your uterus.
• Hysteroscopy: When your healthcare provider inserts a thin, lighted tube into your vagina to take pictures of the inside of your uterus. It can also check to see if your fallopian tubes are open.
• MRI: Uses magnets and radio waves to take pictures of your uterus and other reproductive organs in your pelvis.

What treatments are used for uterus conditions?

Treatment for uterine conditions or diseases depends on the cause of your symptoms. Medications like antibiotics, hormone therapy and surgery are all commonly used treatments.

What is the removal of your uterus called?

A hysterectomy is the surgical removal of your uterus, and most likely, your cervix. Depending on the reason for the surgery, a hysterectomy may involve removing surrounding organs and tissues, such as your fallopian tubes and ovaries.

A note from Cleveland Clinic

Your uterus plays an important role in menstruation, pregnancy and fertility. Your uterus looks like an upside-down pear and sits in your pelvis between your hips. If you were born with a uterus that’s shaped differently, it could cause you pain. Like most organs in your body, your uterus can develop diseases and infections that require medical treatment, too. Call your healthcare provider if you experience pain in your uterus or have issues with your period or getting pregnant.