What Is Cervical Insufficiency in Pregnancy?

Cervical insufficiency in pregnancy can cause premature delivery. Learn more about it and its treatment in this article.
What Is Cervical Insufficiency in Pregnancy?
María Belén Del Río

Reviewed and approved by the doctor María Belén Del Río.

Last update: 27 December, 2022

Cervical insufficiency in pregnancy, also called cervical incompetence or incompetent cervix, represents 10% of the causes of preterm birth (before week 37 of gestation) and is associated with significant neonatal morbi-mortality.

What is cervical insufficiency in pregnancy?

Cervical insufficiency in pregnancy refers to cervix dilation in the absence of contractions before week 37 of gestation. Also, it’s the functional disability to retain gestation before the uterus reaches its delivery size (between 37 and 42 weeks of gestation).

Some women may manifest a sensation of pelvic pressure, increased vaginal discharge, or light vaginal bleeding.

What causes cervical insufficiency in pregnancy?

Although various risk factors can lead to cervical insufficiency, in most cases, it appears even though there’s no previous medical history.

What Is Cervical Insufficiency in Pregnancy?

Some of the risk factors are:

  • History of cervical insufficiency in previous pregnancies.
  • Asymptomatic intra-amniotic infection.
  • Uterine malformations. Septate uterus or bicornuate uterus, among others.
  • Cervix connective tissue defects, either congenital defects or due to cervical surgery.
  • Congenital cervical hypoplasia after exposure to diethylstilbestrol, a type of estrogen that medical professionals use to indicate to pregnant women to prevent spontaneous abortions and premature births.
  • Multiple pregnancies.

How to diagnose cervical insufficiency

A medical professional can assess cervical insufficiency before and after pregnancy. The passage of an object of a given diameter through the cervix, reaching the uterine cavity, without resistance or pain, could indicate a cervical insufficiency. This test reports the permeability of the internal cervical os. Currently, medical professionals don’t regularly do these tests.

Nowadays, the test that’s most commonly used to assess cervical insufficiency is transvaginal ultrasound. This test lets doctors measure the length and dilation of the cervix, the length of the endocervical canal, and the dilation of the cervical os. In addition, it lets doctors see if the membranes are prolapsed through the cervical canal.

Another test doctors may indicate is vaginal examination (pelvic exam), which assesses the consistency of the cervix and its dilation.


To prevent or treat cervical insufficiency in pregnancy, the most-used method medical professionals resort to is cervical cerclage. They can also prescribe vaginal hormone therapy, such as with progesterone, in some cases.

Cervical cerclage consists of suturing the cervix to reduce its expansion and increase its strength. So consequently, it’ll be able to support the weight of the pregnancy and prevent preterm delivery.

As there are different suture techniques, the gynecologist or obstetrician has to decide which is the most appropriate for each case. Thus, there are different types of cerclage:

History-indicated cervical cerclage

This is conducted before any modification appears in the cervix of women with a history of gestational losses due to cervical insufficiency or those who were already treated for it in previous pregnancies.

Ultrasound-indicated cerclage

This is performed on pregnant women with a history of premature delivery who have a cervical shortening (less than 25 mm) before the 26th week of gestation. Initially, medical professionals usually indicate vaginal hormone therapy with progesterone. However, if the modifications continue, they may consider a cervical cerclage.

Physical examination-indicated cerclage.

It’s recommended when, after a physical examination, the medical professionals see that the cervix is dilated more than 2 centimeters with visible membranes through the external cervical os before week 26 of gestation. Experts recommend performing an amniocentesis before the cerclage to make sure there’s no intra-amniotic infection.


In some cases, cervical cerclage is contraindicated:

  • Asymptomatic intra-amniotic infection or clinical suspicion of chorioamnionitis.
  • Vaginal bleeding due to placental pathologies (such as placenta praevia, for example).
  • Contractions.
  • Rupture of the amniotic sac.
  • Fetal death, legal termination of pregnancy, or fetal anomalies incompatible with life.
What Is Cervical Insufficiency in Pregnancy?

Other necessary tests

Before getting a cervical cerclage, you may need other required complementary medical tests:

  • Blood tests.
  • Preanesthetic assessment.
  • Endocervical and vaginorectal swabs (Streptococcus agalactiae beta); the latter from 23-24 weeks of gestation.
  • Amniocentesis if there’s a suspicion of intra-amniotic infection.

An antibiotic and corticosteroid treatment is also administered for fetal lung maturity if the cerclage is performed from week 24 of gestation, in case preterm labor were to occur.

In addition, many medical professionals administer medication to relax the uterus and avoid contractions.

Things to consider

After getting the cerclage, the patient will require a stricter medical follow-up to check that there’s no infection and that the cerclage remains well placed. Also, the medical professional will need to analyze endocervical swabs from time to time.

Likewise, the patient needs to reduce their level of physical activity and also avoid sex until the 34th week of gestation.

The medical professional will remove the cervical cerclage after the patient reaches week 37 of gestation, if there are symptoms of intra-amniotic infection, or if labor begins spontaneously and there’s no way to stop it.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Martínez L.R, Valladares M. (2002). Incompetencia cervical diagnosticada por ultrasonido en la prevención del parto pretérmino. Rev Cubana Obstet Ginecol  [Internet].  2002; 28( 1 ): 18-23. Disponible en: http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S0138-600X2002000100003&lng=es
  • Sobo, T., Ferrero, S., & Palacio, M. (2017). Protocolo: Cerclaje uterino. Hospital Clínic de Barcelona.
  • Olmos, C., Gallego, M., Escribano, D., De La Fuente, P., Olmos, C., Gallego, M., … De Revisión, T. (2002). Insuficiencia istmicocervical y cerclaje Hospital Materno-Infantil “12 de Octubre”. Madrid Ginecología y Obstetricia Clínica 2002;3(3):122-128. Clínica.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.