What is Cervical Insufficiency?
Cervical insufficiency is a condition where the cervix (the lower part of the uterus that connects it to the vagina) is unable to keep a developing baby in the uterus, without the mother experiencing any labor pains or contractions. This is due to some kind of functional or structural problem with the cervix. The cervix ‘ripens’ or softens too early in the pregnancy. It’s rare for cervical insufficiency to be a standalone, well-defined condition. Instead, it’s usually seen as part of a bigger and more complex condition called spontaneous preterm birth syndrome, which results in a baby being born too early.
What Causes Cervical Insufficiency?
Cervical insufficiency, a condition where the cervix is weaker than normal, typically happens in the middle of the second or early third trimester of pregnancy. This weakness can either be something a woman is born with (congenital) or something she develops (acquired).
The most common reason a woman is born with this condition is due to a flaw in how her reproductive organs developed in the womb. Certain genetic disorders like Ehlers-Danlos syndrome or Marfan syndrome can also cause this condition. These disorders make the body’s collagen, a protein that gives the body’s tissues their strength, deficient. This can weaken the cervix and cause it to not function as it should, leading to cervical insufficiency.
Cervical insufficiency can also develop from injuries to the cervix. This can happen due to a tear during childbirth, cervical conization (a medical procedure to remove abnormal tissue from the cervix), LEEP (loop electrosurgical excision procedure, another treatment for abnormal cells on the cervix), or forced dilation of the cervix during a procedure to clear the uterus in the first or second trimester of pregnancy.
In many patients, changes to the cervix are often due to either an infection or inflammation, which makes the body start getting ready for labour too soon.
Risk Factors and Frequency for Cervical Insufficiency
Cervical incompetence, a condition that can lead to miscarriage, is estimated to affect about 0.5% of pregnant women overall. However, it has a much higher occurrence, around 8%, in women who have previously had a miscarriage in the middle of pregnancy. The reported rates of this condition can vary widely. These differences are often due to factors such as the specific group of people studied, the methods used to diagnose the condition, and differences in reporting between general doctors and specialized centers.
Signs and Symptoms of Cervical Insufficiency
Cervical insufficiency, a common cause for miscarriages in the late stages of pregnancy, is often identified only after a woman experiences a loss during the second trimester. In many cases, women may not experience any symptoms, or the symptoms might be mild that begins in early second trimester. They may experience abdominal cramps, backache, pelvic pressure, an increase in the volume of vaginal discharge or change from clear to pink, and spotting.
Generally, cervical insufficiency is diagnosed in the following conditions:
- Sudden appearance of symptoms that signal cervical insufficiency
- A history of late miscarriages that suggest cervical insufficiency
- Ultrasound findings indicating cervical insufficiency
Typically, a physical examination may reveal a cervix that has opened (dilated) 2 cm or more, more than 80% thinning (effacement), and the amniotic sac (bag of waters) visible or protruding into the vagina. Diagnosis is often made after multiple unsuccessful pregnancies.
Testing for Cervical Insufficiency
Cervical incompetence is a condition that is usually diagnosed when there’s a history of painless expansion of the cervix and unexpected births during the middle of pregnancy, typically resulting in the birth of a live baby. Diagnosis can be supported if other conditions that can weaken the cervix are present. But it can be hard to confirm this condition since past pregnancies’ records may not have noted important information – and the diagnosis relies on a subjective assessment.
There are various tests that have been used in the past to detect cervical incompetence. These include taking a kind of x-ray of the uterus and fallopian tubes known as a hysterosalpingogram, examining how a balloon attached to the cervix responds to pulling, measuring the openness of the cervix with certain medical instruments, and a number of other tests which all relate to the upper part of the cervix in non-pregnant women. These tests are mostly of historic interest and aren’t commonly used anymore since they haven’t been thoroughly proven to be effective.
Diagnosing cervical insufficiency can be quite challenging because there aren’t any clear, objective diagnostic criteria. However, ultrasound of the cervix has proven to be a reliable diagnostic and screening tool, especially for women at high risk due to a history of spontaneous preterm births. This test is typically performed via a transvaginal ultrasound, which may reveal a shortened cervix or bulging of the amniotic sac into the upper part of the cervix which is dilated, but with a closed lower part of the cervix.
Treatment Options for Cervical Insufficiency
There are various methods, both non-surgical and surgical, that have been suggested for treating cervical insufficiency, a condition where the cervix (the lower part of the uterus) is weaker than normal, which might potentially lead to a miscarriage or premature birth. Some non-invasive treatments, such as bed rest, pelvic rest, and limiting physical activity, have not shown to be effective for this condition, so they’re generally not recommended.
Another non-surgical option in some cases is the use of a vaginal pessary. A pessary is a device that’s inserted into the vagina to support the uterus. There is some limited evidence that using a pessary might be beneficial in certain high-risk patients, though more research is needed.
On the surgical side, there are procedures known as cervical cerclages. These involve placing a stitch around the cervix to provide additional support. There are two main types of these procedures performed vaginally: the McDonald and modified Shirodkar techniques.
The McDonald procedure entails using a special type of stitching material to make several loops around the cervix while being careful not to injure nearby organs like the bladder or rectum. The knot is tied at the front part of the cervix which makes the knot easy to locate and untied later.
The Shirodkar method is a bit more involved. It includes a step where the surrounding tissue is separated from the cervix to allow the stitch to be placed as close to the internal part of the cervix as possible. After the stitch is secured, the tissue is put back in place.
In both methods, nonresorbable stitches, or ones that don’t dissolve, are used.
Sometimes, in an emergency situation, a patient receiving a cerclage treatment might be positioned with their feet higher than their head and a special catheter with an inflatable balloon is inserted through the cervix. The balloon helps gently push the membranes back into the uterus while the stitch is tightened, and then it’s slowly deflated.
Another surgical method, called the transabdominal cerclage, places the stitch at the entry point of the uterus. This is often used in severe cases or when previous interventions failed. It can be performed laparoscopically, which involves making small incisions, though sometimes it may require a larger incision for placing and later removing the stitch.
What else can Cervical Insufficiency be?
These are some conditions that may complicate a pregnancy:
- Abruptio placentae (when the placenta separates from the womb prematurely)
- Fetal growth restriction (when the baby doesn’t grow at a normal rate in the womb)
- Multifetal pregnancy (carrying more than one baby at a time)
- Preeclampsia (a condition causing high blood pressure and damage to organs)
- Premature rupture of membranes (when the water breaks early)
- Preterm labor (when labor starts too early, before 37 weeks of pregnancy)
