As an MFM specialist, I see a variety of medical conditions that affect pregnancy and delivery outcomes. One such condition is cervical insufficiency that leads to preterm birth (PTB) and pregnancy loss (PL). Today, I want to share with you more about this condition, as well as discuss measures to help prevent PTB.
If you have experienced PTB or PL due to cervical insufficiency and are pregnant or plan on getting pregnant, this is an important topic to understand to help support conversations between you and your healthcare provider. 15 million babies are born prematurely every year resulting in short- and long-term disability, and even death. Thankfully, we have measures that can help prevent PTB.
Keep reading to learn more!
Sometimes the cervix isn’t strong enough to stay closed as a pregnancy grows. Formerly called an’ incompetent cervix’, this condition is now called ‘cervical insufficiency’. By definition, it is “the inability of the cervix to retain a pregnancy in the absence of the signs and symptoms of clinical contractions, or labor, or both in the 2nd trimester.” Cervical insufficiency may cause a quick delivery, PTB or PL. Diagnosis is based on a history of painless cervical dilation in the 2nd trimester with subsequent delivery of the fetus in the 2nd trimester. This typically occurs before 24 weeks of gestation, without contractions or labor and in the absence of other clear pathology (eg, bleeding, infection, ruptured membranes).
Those with the shortest cervical length (CL) have the highest risk of preterm delivery. The finding of a short CL, regardless of a prior history of preterm birth or pregnancy loss, has been consistently associated with an increased risk of spontaneous PTB. Patients with a prior spontaneous PTB and a short CL are at the highest risk of delivering prematurely. However, a short CL in the second trimester before 24 weeks is not diagnostic of cervical insufficiency.
Placement of an elective or prophylactic cervical cerclage is an option for those patients with a history of PTB and PL due to cervical insufficiency that involves temporarily sewing the cervix closed with a stitch. An elective or prophylactic cerclage is done at 12-14 weeks of pregnancy to help prevent PTB.
Your ObGyn may recommend placing an elective cerclage if you have had one of the following:
Your ObGyn may recommend placing a "rescue", "emergent" or "exam-indicated" cerclage based on 1) painless dilation of the cervix in the 2nd trimester before 24 weeks in patients with or without a history of PTB or 2) an ultrasound exam that shows a cervical length of <2.5cm at less than 24 weeks if you also have other risk factors for PTB.
I explain how a cerclage is done to help you understand what to expect in the video below!.
There are two types of cerclage--transvaginal cerclage and transabdominal cerclage. Both procedures are done in the hospital under anesthesia, but do not typically require an overnight stay.
Transvaginal cerclage is done through the vagina to place a stitch in the cervix, which is then typically removed around 37 weeks of pregnancy in the office or hospital. Transabdominal cerclage is an open abdominal surgery (laparotomy) or laparoscopic surgery done to place a cerclage stitch higher up on the cervix from inside the abdomen. It is typically left in place until delivery through a cesarean. A transabdominal cerclage can also be left in place between pregnancies, to prevent future PTB or PL.
As with most medical treatments, especially those related to a process as complex as pregnancy, there are possible complications with cerclage placement. These include:
*preterm prelabor rupture of membranes (PPROM)
*infection of fetal membranes and the uterus
*tears in the cervix
*the stitch moving from the correct place
*bleeding during or after the procedure
Bed rest is not recommended for those at risk of PTB or those who have had a cerclage placed. Research shows that bed rest and limiting physical activity do not prevent PTB or pregnancy loss. Bed rest can increase the risk of blood clots, bone weakening, and loss of muscle strength.
In this Instagram post, I share more specifics about cerclage in patients with twin gestations and a cervical length of <2.5cm. There are studies on this, and overall there is not an indication to recommend placing a cerclage in twin pregnancies with a short cervix. However, the evidence is sufficient to remove any recommendation against cerclage. You can go to this article by SMFM for more info.
Serial CL measurements ARE NOT recommended after cerclage placement.
If the CL is less than or equal to 25mm before or at 24 weeks of gestation and the patient does NOT have a history of a prior singleton PTB, a cerclage is not indicated.
In addition, you can read more about the latest info on routine cervical length screening and cervical cerclage from ACOG AND SMFM in this post, or go to my Instagram highlight “preterm birth” for more info!
As a patient, having the knowledge and understanding about health conditions and treatment options should empower you. My hope is that the Babies After 35 blog and community empower you in your journey!
Shannon M. Clark, MD, MMS is a double board certified ObGyn and Maternal-Fetal Medicine Specialist, and founder of Babies After 35. In her roles as a clinician, educator and researcher at UTMB-Galveston, she focuses on the care of people with maternal and/or fetal complications of pregnancy. Dr. Clark has taken a special interest in pregnancy after the age of 35, which according to age alone, is considered a high-risk pregnancy.
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