Patient education: Cervical insufficiency (The Basics)

What is cervical insufficiency? — The cervix is the bottom part of the uterus that leads to the vagina (figure 1). During pregnancy, the cervix stays closed until labor starts. Then, it softens, thins out (effaces), and opens up (dilates). This lets the baby move down through the vagina for birth.

"Cervical insufficiency" is when the cervix starts to open too early in pregnancy, without other signs of labor, during the second trimester. This can lead to pregnancy loss (miscarriage) or preterm birth. There are ways to lower the risk of these problems.

What causes cervical insufficiency? — Doctors do not know. But your risk is higher if you:

●Have had a past pregnancy loss or preterm birth in the second trimester

●Have had surgery or another procedure on your cervix

●Have certain conditions that make your cervix weaker than normal

What are the symptoms of cervical insufficiency? — Many people do not have any symptoms. When symptoms do happen, they are usually mild and start between about 14 and 20 weeks of pregnancy.

Symptoms can include:

●A feeling of pressure in the lower belly, pelvis, or vagina

●Mild cramping or backache

●Increased mucus-like vaginal discharge that might look pink, tan, or red

Should I see a doctor or nurse? — Call your doctor, nurse, or midwife if you are less than 24 weeks pregnant and have any of the above symptoms.

Is there a test for cervical insufficiency? — Yes. A test called a "transvaginal ultrasound" can show if your cervix has started to thin out (shorten) or open. But this test is not always needed.

Doctors might diagnose cervical insufficiency based on:

●Past pregnancies – If you have had 2 or more pregnancy losses or births in the second trimester with no (or few) contractions, you might have cervical insufficiency.

●Ultrasound – For a transvaginal ultrasound, the doctor or midwife puts a thin wand into your vagina. This creates pictures of your cervix and nearby organs, and can show if your cervix is short or open. You might get regular ultrasounds to check your cervix if you have a high risk for cervical insufficiency.

●Pelvic exam – In some cases, your doctor or midwife can tell that you have cervical insufficiency by doing a pelvic exam. They can see that your cervix is short and open.

You might also get tests to check for infection. These can include urine tests or tests on a sample of amniotic fluid. (This is the liquid that surrounds the fetus inside the uterus.)

How is cervical insufficiency treated? — The main treatment is a "cervical cerclage." A cerclage is a stitch to help keep the cervix closed. This can help lower the chances of going into labor too early.

Your doctor or midwife will probably recommend a cerclage if:

●You know that you have cervical insufficiency based on your past pregnancies – In this case, the cerclage is usually done between 12 and 14 weeks of pregnancy.

●An ultrasound or pelvic exam shows that you have cervical insufficiency – Cerclage is usually done before 24 weeks of pregnancy. You might first need a test to make sure that you do not have an infection.

Most of the time, the doctor can go in through the vagina to place the stitch. It is removed at 36 to 37 weeks of pregnancy, or sooner if labor begins before this. In some cases, the stitch is placed through the belly. To do this, the doctor makes an incision (cut) in the belly. If this is done, most people will have a cesarean birth at 36 to 38 weeks of pregnancy. The stitch can be removed at that time or stay in place for a future pregnancy.

Your doctor might prescribe a hormone called "progesterone" instead of or along with cerclage. It comes as a tablet or gel you put into your vagina. This can help lower the chances of preterm birth.

Most people with cervical insufficiency do not need to be on bedrest. But your doctor or midwife will talk to you about your situation. They can give you advice on whether you should change or stop any of your normal activities.

Will I give birth before my due date? — There is no way to predict this for sure. Treatment lowers the chances of going into labor early. But it cannot always prevent it.

What if I want to get pregnant again? — It's important to talk to your doctor, nurse, or midwife about your past pregnancies. They will use this information to plan the best care for you. For example, if you had a cerclage that worked, you might get this again in your next pregnancy. Or, you might get regular transvaginal ultrasounds to check your cervix.

More on this topic

Patient education: Preterm labor (The Basics)
Patient education: Pregnancy loss (The Basics)
Patient education: Amniocentesis (The Basics)

Patient education: Preterm labor (Beyond the Basics)
Patient education: Pregnancy loss (Beyond the Basics)