Wonderful World of Pregnancy

What Causes An Incompetent Cervix?

In a normal pregnancy, the cervix remains open until the moment of delivery when it starts to dilate and thin to allow the passage of the baby.

What Causes Incompetent Cervix

But sometimes, the cervical dilation triggers prematurely, without being caused by birth, but rather by the weakness of the cervix itself. This medical condition is known as cervical incompetence and can have various causes, the most important one being a wound on the cervix.

What Is Cervical Incompetence?

Cervical insufficiency or incompetence is a pathology associated with pregnancy in which the cervix opens before the pregnancy reaches the term or in the absence of labor. The effects of a cervical insufficiency are noticed during the second and third trimester of pregnancy, when the internal cervix opens, followed the premature rupture of the membranes and abortion or preterm birth, depending on the moment of pregnancy development.

What Is a TAC Surgery?

A TAC (transabdominal cerclage) procedure is the perfect medical treatment for a woman who suffered several losses because of cervical malformations or damages or previous failed tansvaginal cerclage. Just as with any other type of surgery, there are certain risks involving such procedures. Women need to have a discussion with their doctor about the possible benefits or risks.

What Is the Normal Length of a Cervix?

A normal cervix is of 4 – 5 cm when not expecting. A study discovered that at 24 weeks of pregnancy, the average length of the cervix is of 3.5 cm. When the length of the cervix is under 2.2 cm, a woman might face a 20% probability of premature birth.

What Causes You to Have a Short Cervix?

The causes of cervical incompetence split into 2 main groups:

  • Cervical trauma due to some obstetric or gynecological procedures (coniosation, dilation for aspiration or curettage, cracks during a previous birth, etc).
  • Congenital causes – which weaken the cervix.

An incompetent cervix cannot support the fetus`s weight and dilates without any contractions or pain, sometimes opening completely. Due to dilation, the amniotic membranes “drop” through the opening and break, which irritate the uterus and lead to labor, often even before the fetus is able to survive outside the uterus. In a lot of cases, labor is too advanced to be stopped.

Studies have shown that if the woman has suffered surgical cervical dilatations, the risk of cervical insufficiency depends on the number of dilatations suffered and their severity.

If the surgical dilation has been made following a miscarriage, there are small chances of a cervical incompetence. Regarding induced abortions, it was noticed that only after 3 such interventions, the risk for the woman to have an incompetent cervix increases by 12%.

What Are the Signs of an Incompetent Cervix?

If you have an incompetent cervix, you may not have a sign or symptom while the cervix starts to open during your early pregnancy. It`s possible for you to experience a slight discomfort over a few days or weeks, but starting with the week 15 or 20 of pregnancy. Some symptoms may be:

  • A sensation of pelvic pressure.
  • Back pain.
  • Small abdominal cramps.
  • A change in the vaginal discharge.
  • Small vaginal bleeding.


An incompetent cervix poses a risk for pregnancy, especially during the second trimester of pregnancy, including:

  • Premature birth.
  • Loss of pregnancy.

If a baby is born prematurely, he may risk having some medical issues, including poorly developed organs, low birth weight and shortness of breath. Children who are born before term also have a higher risk of behavioral issues and learning disabilities. These risks are somehow greater for children who are born before the week 32 of pregnancy.

Investigations & Diagnosis

Cervical insufficiency can be diagnosed during pregnancy, and even when the diagnosis is difficult, especially if it`s the first pregnancy. There`s no test that can be done before remaining pregnant and which to predict adequately if the cervix is incompetent. – Click on this link!

The diagnosis of cervical incompetence can be attributed to a history of pregnancy loss in the second and third trimester of pregnancy, without any other pathologies being identified, or it can be diagnosed by ultrasound if the cervical shortening and dilation is noticed before pregnancy loss or premature birth.


If you have less than 24 weeks of pregnancy, a history of premature birth or the ultrasound has showed that the cervix is open, the obstetrician will recommend a surgical procedure that is known as cerclage, which should prevent premature birth. During this surgical procedure, the cervix is sewn to remain closed until the term, and the sutures are removed in the last month or during labor.

Also, if you have a history of premature birth whose cause is cervical insufficiency, a prophylactic circularization will be performed before the cervix starts to open. This medical procedure is performed before the week 14 of pregnancy.

In addition, it will be recommended to you to restrict your physical activities and sexual contacts. Although it wasn`t proven to be a remedy for premature birth, in some situations your obstetrician will recommend you bedtime rest.

How to Prepare?

If you are expecting a baby and you have a risk factor for cervical insufficiency or have experienced a symptom during the second trimester of pregnancy, which indicate the possibility of an incompetent cervix, visit your doctor immediately. Depending on the circumstances, you may immediately need medical attention.

What Can You Do?

Before scheduling a visit to the doctor, you could:

  • Ask about the pre-visit restrictions. In most situations, you`ll be immediately allowed for a pre-visit. If this isn`t the case, you should still ask your doctor if you should restrict your activities, while you are waiting for the visit to take place. – Check this web!
  • Find a close person or friend who can stay with you during these medical visits. Fear and anxiety might distract you from what the doctor has to say. Bring someone with you who is able to remember all the info the doctor has to tell you.
  • Write down on a piece of paper the questions that you want to ask your doctor. This way, you won`t forget anything and can make the most of your time spent at the doctor`s office.

Below you can find a few basic questions that you can ask your doctor about cervical incompetence. Still, if during your visit you want to ask other questions that you didn`t thought in advance, don`t hesitate to ask them:

  • Has the cervix begin to open? If so, how much?
  • Is there anything I can do to prolong the pregnancy?
  • Is there any treatment that can prolong the pregnancy or can help my baby?
  • Do I need to rest in bed? If so, for how long?
  • What activities am I allowed to do? – More info!
  • Do I need to be in a hospital?
  • What signs should make me call you?
  • What symptoms should make me go to the hospital?
  • What will happen to my baby if he`ll be born now? What should I expect?

What to Expect from your Doctor?

Also, your doctor may ask you a few questions, like:

  • When did you notice the signs for the first time?
  • Did you have any contractions or change in your vaginal discharges?
  • Have you previously had any pregnancies, miscarriages or cervical surgeries?
  • How much time it would take for you to reach the hospital in case of an emergency?
  • Do you have any friends or close persons around you that could take care of you if you need to rest?
Image courtesy of PregMed.org

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