What Is an Incompetent Cervix?

The experience of fetal loss is a difficult experience. History of fetal loss in the second to early third trimester after pain-free cervical dilation, ruptured membrane (water break) or prolapsed membrane, and the birth of a live fetus with minimal uterine activity is attributed to cervical incompetence (insufficiency).¹ 

The cervix is the lower part of the uterus that connects it to the birth canal, known as the vagina. During pregnancy, the cervix remains closed, acting as a door to hold the baby inside the uterus. It is only when the baby reaches the complete term that the cervix decomposes and expands (open) to let the baby out through the birth canal during a normal vaginal delivery.

Cervical insufficiency is a condition where the cervix becomes weak and opens in the early stages of pregnancy. As the baby starts growing and increasing in weight, it starts to apply pressure on the cervix, and if the cervix is not strong enough, it falls under pressure from the developing baby.

Cervical insufficiency (or incompetence) is a pathology (disease/illness) associated with pregnancy; the cervix opens before the pregnancy reaches full term or in the absence of labour. The effects of an incompetent cervix are observed in the second or third trimester of pregnancy, when the internal cervical opening enlarges, followed by premature rupture of the membranes and miscarriage or premature birth (depending on the time in the evolution of the pregnancy).

Overview

In other words, cervical insufficiency, previously referred to as cervical-isthmic incompetence, outlines a functional condition of cervical continence deficiency in the absence of uterine contractions, which leads to the failure to preserve full-term pregnancy.1 A person is diagnosed with classic cervical insufficiency when they have a history of repeated fetal loss during the second trimester or during the beginning of the third trimester after painless cervical dilation.² 

In the absence of the classic recurrence (when a person does not have a history of repeated fetal loss), the expression incompetent cervix is usually used as a diagnosis based on a single event with the same characteristic after eliminating other potential causes of premature delivery.¹ 

Causes of incompetent cervix

Causes of premature cervical dilatation can often include having a shorter cervix than normal or weakening of the cervical muscles. So, while it's not clear what causes cervical insufficiency, you're more likely to experience cervical insufficiency if:

• You have had a procedure, such as a cervical biopsy
• The cervix was injured during a previous birth or curettage
• You have had one or more miscarriages in the second trimester without a known cause
• You have had cervical insufficiency in a previous pregnancy
• You have had one or more spontaneous premature births
• You have a uterine abnormality
• You have a congenital disorder that affects connective tissue, such as Ehlers-Danlos syndrome

 In conclusion, the causes of cervical incompetence are divided into 2 large groups:

•  Cervical trauma due to previous obstetric or gynaecological procedures
•  Congenital causes that cause weakening of the cervix

Signs and symptoms of incompetent cervix

If you have an incompetent cervix, you may have no signs or symptoms, even if the cervix starts to open early in pregnancy. However, beginning with the 15-20 weeks of pregnancy, you may notice a slight discomfort that lasts a few days or weeks. Pay attention to these symptoms:

• Sensation of pelvic pressure
• Back pain
• Slight abdominal cramps
• Change in vaginal discharge
• Slight vaginal bleeding

Management and treatment for incompetent cervix

If you have risk factors for cervical incompetence, your healthcare provider may advise you to take progesterone supplements as early as your second trimester.

Surgical management of cervical incompetence is cervical cerclage, which refers to a range of procedures that use sutures (stitches) or synthetic tape to enhance the cervix. Cervical cerclage may take place through the vagina (transvaginal cervical cerclage) or, less often, via the abdomen (transabdominal or laparoscopic cervical cerclage) and ideally should be done prior to or at the beginning of the pregnancy. Both vaginal and abdominal approaches have benefits and drawbacks. Currently, the most common method is the transvaginal approach, but in case of failure, laparoscopic cervical cerclage is recommended.³

Before performing the cervical cerclage procedure, the attending medical practitioner will evaluate the health status of the mother and fetus. Assessing the presence of uterine infections and excluding premature rupture of the amniotic membranes is very important before operation.

Usually, cervical cerclage is performed between weeks 12–14 of pregnancy. However, cerclage may be performed up to 23 weeks of pregnancy if cervical dilation is noted at physical examination and ultrasound assessment. Intervention should be avoided after 24 weeks of pregnancy due to the increased risk of preterm birth.

Lately, the idea of using vaginal pessaries as a new, less invasive treatment method. A cervical pessary can provide a simple and safe substitute for cerclage to treat cervical failure and prevent premature birth.4 The obstetric pessary is a product widely used in obstetrics. Its main purpose is to support the cervix, reduce the pressure placed by the fetus, spread the load, and prevent premature birth. The most common design is in the form of a plastic or silicon ring. The insertion of the obstetrical ring protects the pregnancy until delivery. The device is made of a material that causes no allergies and easily adapts to the anatomical features of the uterus. It is soft but resilient enough to fulfil its purpose.

Diagnosis

Diagnosis of cervical failure is difficult due to the absence of objective results and clear diagnostic criteria. Cervical ultrasound appears to be a clinically proven and useful screening and diagnosis tool for the selected population of high-risk women based on an obstetric history of prior (early) spontaneous premature birth.⁵ 

Transvaginal ultrasound usually shows your pelvic cavity and the organs inside your pelvis. These organs include your cervix, uterus, fallopian tubes and ovaries.  This ultrasound can show abnormal structures or growths in your pelvic area that may indicate a condition or disease and can also help to confirm or monitor your pregnancy. Cervical insufficiency is defined by a transvaginal ultrasound when the cervical length is less than 25 mm before 24 weeks in women who lost their pregnancy or delivered prematurely between 14 and 36 weeks.⁷

Risk factors

Although countless theories are postulated, it seems that a general agreement has been reached. The most frequent cases of cervical incompetence are due to old lesions of the cervix or infection arising from the vagina with consequent inflammation. Older lesions of the cervix are most often caused by surgical procedures at this level (conizations, electroresections), births or abortions in the second trimester (rupture of the cervix at birth).

Complications

Without specialized treatment, abortion or premature birth may occur.In unusual cases, treating cervical failure (cerclage) can lead to complications such as:

• Internal bleeding
• Infection
• Laceration (cut or tear) on the cervix
• Uterine rupture

FAQs

Can an incompetent cervix be prevented?

There's not much you can do to prevent an incompetent cervix before you conceive. 

However, once you become pregnant, you can go through these simple steps to achieve a successful pregnancy:

• Get the right nutrients: You can eat lots of fresh fruits, vegetables and nuts to get the right amount of nutrients during pregnancy. Calcium, iron and folic acid are essential to ensure mother and baby health
• Check with your doctor on a regular basis: If you have a history of miscarriage or premature delivery, be sure to check with your doctor on a regular basis. The doctor will periodically check the condition of the cervix by ultrasound and offer the necessary precautions for a safe delivery
• Reduce physical activity: If you are at risk for cervical incompetence, try to avoid intense physical activity. You may opt for bed rest, in particular after the second trimester
• Avoid sexual activity: Your physician may advise you to avoid any sexual activity during your pregnancy if you have a weak cervix

How common is an incompetent cervix?

Cervical insufficiency can occur in as many as 1% of obstetric populations.⁶ 

What can I expect if I have an incompetent cervix?

Pregnancies in patients with a history of spontaneous abortions, premature births or previous interventions on the cervix are considered high-risk and must be closely monitored. The doctor will determine how often you must return for the ultrasound and when/ if you’ll do a cerclage. 

When should I see a doctor?

Most pregnancy care providers diagnose cervical incompetence after a second-trimester miscarriage or premature birth. Talk to your provider if you notice any signs of miscarriage during pregnancy, such as bleeding, pelvic pain and contractions.

Summary

 Cervical insufficiency is a condition where the cervix becomes weak and opens in the early stages of pregnancy. As the baby starts growing and increasing in weight, it starts to apply pressure on the cervix, and if the cervix is not strong enough, it falls under pressure from the developing baby, leading to the failure to preserve full-term pregnancy.

Cervical failure may be diagnosed in women with and without pregnancy loss. Cervical insufficiency was defined by a transvaginal ultrasound whose cervical length is less than 25 mm before 24 weeks in women who lost their pregnancy or delivered prematurely between 14 and 36 weeks. There's not much you can do to prevent an incompetent cervix before you conceive. 

Surgical management of cervical incompetence is cervical cerclage, which refers to a range of procedures that use sutures or synthetic tape to enhance the cervix. Talk to your provider if you notice any signs of miscarriage during pregnancy, such as bleeding, pelvic pain and contractions.