Overview of Cervical Cerclage
During pregnancy, the neck of the womb or cervix usually stays long, thick and strong until the final stages. Then, it gently begins to soften, open up and thin out for the baby to pass through. Sometimes, the cervix can’t keep its strength and may cause a miscarriage or early childbirth. This condition, where there aren’t any clear signs or symptoms of labour, is called cervical insufficiency or incompetence.
Previously, methods like limiting physical activity and resting were suggested to manage this condition. However, these techniques have not shown helpful results and are not recommended now.
A surgical procedure, called cervical cerclage, is available. This operation aims to keep the cervix strong to extend the pregnancy term and improve the chances of a successful childbirth.
Anatomy and Physiology of Cervical Cerclage
The causes of cervical insufficiency, a condition where the cervix cannot hold a pregnancy, aren’t well understood yet. There’s thought to be a problem with the structure of the cervix or the way it functions. There are some things that could raise your risk, including any procedures or trauma to the cervix in the past.
This could be procedures such as a loop electrode excisional procedure, which is when a small loop of wire with an electrical current is used to remove abnormal cells from the cervix or a cone biopsy, a test where a small cone-shaped piece of tissue is removed from the cervix. Cervical insufficiency could also be caused by past cervical tears, repetitive widening of the cervix, or terminating pregnancies.
Beyond these, other potential causes may include diseases or abnormalities affecting the tissues that connect parts of the mother’s body, anomalies that the mother was born with such as abnormal formation of the uterus or fallopian tubes, or the mother’s exposure to a drug called diethylstilbestrol while she was still in her mother’s womb. Diethylstilbestrol is a hormone previously used to prevent miscarriages which has been since found to cause health issues.
Why do People Need Cervical Cerclage
The American College of Obstetricians and Gynecologists (ACOG) suggests three main reasons for a procedure called cervical cerclage. Cervical cerclage is a stitch or a set of stitches placed in the cervix to help prevent premature birth or miscarriage. The cervix is the lower part of the uterus that opens to the vagina.
The first reason, known as history-indicated or prophylactic cerclage, occurs when a woman has experienced one or more miscarriages in the second three months of pregnancy related to the cervix opening painlessly and before labor starts or a problem called abruptio placentae, which is when the placenta separates from the uterus too early. It’s also done if the woman previously had a cervical cerclage because the cervix was too weak to stay closed in the second three months of pregnancy.
The second reason, named ultrasound-indicated cerclage, might be considered if a woman has a history of unexpected loss or preterm birth before 34 weeks of pregnancy and in the ongoing pregnancy with a single baby, an ultrasound test has shown that the cervix is less than 25 mm long before 24 weeks of pregnancy have passed. However, this recommendation is only valid if the woman has experienced a preterm birth before.
The last reason, referred to as physical examination-indicated cerclage or emergency or rescue cerclage, should be considered if a pregnant woman with a single baby, less than 24 weeks pregnant, who is found to have an unusually opened cervix without any contractions or signs of intraamniotic infection (infection within the amniotic sac, the bag of waters around the baby) or placental abruption (when the placenta separates from the uterus before the baby is born).
When a Person Should Avoid Cervical Cerclage
The American College of Obstetricians and Gynecologists (ACOG) doesn’t directly state that there are situations where cerclage, a procedure to help prevent premature birth, absolutely shouldn’t be done. However, it’s important to keep in mind the considerations previously mentioned. Moreover, it’s usually not advised to perform this procedure on pregnancies with more than one baby.
How is Cervical Cerclage performed
Transvaginal cervical cerclage is a surgical procedure performed to prevent or treat cervical incompetence, also known as a weak cervix, which can lead to a miscarriage or premature birth. Let’s discuss two common techniques: the McDonald method and the Shirodkar technique.
The McDonald method is the most frequently used and it was first performed in 1951. Here’s how it’s done: Under anesthesia, the patient is positioned on her back with her legs in stirrups. The inside area is cleaned with a disinfectant solution. A speculum, which is a medical tool used to widen the opening, or a right-angle retractors is used to widen and hold open the cervix for clear visibility. The doctor then gently holds the front part of the cervix using ring forceps and locates the vesicocervical junction, which is the landmark used in this procedure. The doctor then carefully stitches a nonabsorbable or long-lasting suture around the cervix, taking care to avoid important blood vessels in the area. The stitch is then securely tied in a knot.
The Shirodkar technique involves similar initial steps. The critical difference lies in that after identifying the vesicocervical reflection, which is the junction between the bladder and the cervix, a small cut is made in the cervix. This cut is made similarly to a vaginal hysterectomy, which is a surgical removal of the uterus through the vagina. The bladder is then gently lifted and pulled upwards. These steps are repeated on the back part of the cervix. A significant step in this technique is that the stitch is passed from the front to the back keeping it slightly below the Allis clamp, a type of surgical clamp used to hold or secure tissues – this prevents entering the cervical opening. The stitch is then tied securely at the front. Lastly, the layers of the cervix are sewn back together to cover the stitch – this can be done using either a running or interrupted suturing technique with a material that eventually dissolves over time.
The timing of the cerclage operation varies depending on the reason for the procedure. Ideally, the procedure should be carried out before 24 weeks of pregnancy for those women who need it based on ultrasound or physical examination findings. For women with a history of previous late miscarriages or early preterm birth, the procedure is usually performed between 12-14 weeks of pregnancy.
The decision on which technique to use often depends on the ease of performing the procedure and removing the stitch at a later time. Therefore, the McDonald method is usually chosen. But in cases where a transvaginal cerclage has not been successful in the past, an abdominal cerclage may be considered, which is a similar procedure done by making a small incision in the abdomen.
The cerclage stitches are usually taken out around weeks 36-38 of pregnancy, before labor begins. But if preterm labor is suspected, the stitch should be removed immediately to avoid potential harm to the cervix. If a cesarean section (C-section), a surgical delivery of a child, is planned, the stitch may be taken out at the same time.
Possible Complications of Cervical Cerclage
Every medical procedure, including this one, carries some level of risk. It’s believed that cerclages, a type of surgery used to help the cervix stay closed during pregnancy, guided by ultrasound or suggested by a physical examination might come with higher risks compared to those recommended based on medical history. The possible complications can include infection or severe infections known as sepsis, accidental breaking of amniotic sac which surrounds and protects the baby during pregnancy, cuts at the site of surgery, and complications related to the use of anesthesia. Additionally, recent research indicates that if the cervix is dilated more than 4cm at the time of the cerclage procedure, the outlook might not be favorable.
When deciding on this procedure, it’s crucial to measure these risks against the expected benefit. The main aim of a cerclage is to provide structural support to the cervix, helping prevent premature birth. All these aspects should be considered when making healthcare decisions.
What Else Should I Know About Cervical Cerclage?
Preterm birth, or having a baby before the 37th week of pregnancy, can cause serious health problems for the baby. One of the main reasons for a preterm birth is having had one before. Another reason could be cervical insufficiency – this is when the lower part of the woman’s uterus, the cervix, is weak or cannot stay closed during pregnancy, leading to miscarriage or preterm birth.
One way doctors have been helping to prevent preterm birth since the 1950s is by using something called a cervical cerclage. This is a procedure where they stitch the cervix closed to help it stay shut, supporting the pregnancy. There’s an ongoing debate about how effective this treatment is, but a big study in 2017 found that women who had a cervical cerclage were less likely to give birth prematurely.
However, this can change depending on the reason the cerclage was done in the first place. For instance, a review found that women who had an elective cerclage (chosen by the doctor and patient) had babies further along in the pregnancy and these babies had healthier weights compared to women who had an emergency cerclage (done because of an immediate risk to the pregnancy). Also, the women who had the emergency cerclage were more likely to have a premature rupture of membranes (when the water breaks early).
So, while every patient and every situation is unique, a cervical cerclage can be a helpful tool to potentially delay preterm birth in certain cases.
