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Cervical Incompetence

What is an incompetent cervix?

Before pregnancy, the cervix is normally closed and firm. As pregnancy advances towards the time of labour, the cervix slowly becomes soft, decreasing the length and may even open slightly. When the cervix is unable to stay closed during the pregnancy and opens without labour, this is called an incompetent cervix or cervical insufficiency. It occurs as a result of the weakness of the tissue of the cervix and can contribute to premature birth or spontaneous miscarriage. The diagnosis of an incompetent cervix may be challenging, as can be its treatment.


Symptoms are usually not evident during the early stages of pregnancy.  Some women can present a mild discomfort or spots of blood over the course of several days starting between 14 and 20 weeks of pregnancy. These symptoms may be accompanied by pelvic discomfort, lower back pain radiating to the lower abdomen, abdominal cramps and change on the vaginal discharge.


Risk factors.

Risk factors for incompetent cervix include:

  • Cervical trauma.
    • Some surgical procedures utilized to treat cervical abnormalities associated with an abnormal cervical screening can result in cervical insufficiency. Multiple surgical evacuations of the uterus after a miscarriage may be another factor related to cervical insufficiency.
  • Race.
    • Some studies have shown that African women have a higher risk of developing incompetence of the cervix.
  • Congenital disease.
    • Uterine abnormalities and genetic disorders affecting collagen sometimes are related with an incompetent cervix.
  • Exposure to diethylstilbestrol (before birth also has been connected to cervical insufficiency.



An incompetent cervix may lead to a premature birth or spontaneous miscarriage in the mid-trimester.



There is no known way to completely prevent the occurrence of an incompetence of the cervix.



The diagnosis is based on the history of the pregnant woman (symptoms, history of  prior premature birth or miscarriage etc) and the physical exam during the pregnancy.


Women affected with this condition usually have a history of painless cervical dilation and deliveriy before 24 weeks of pregnancy.  

There are some tests and procedures can help to diagnose an incompetent cervix during the second trimester:

  •    Transvaginal ultrasound. The transvaginal ultrasound is utilized with the aim to evaluate the length of the cervix. It is considered the gold standard in the diagnosis of this pathology.

  •    Pervaginal and pelvic examination. The characteristics of the cervix need to be evaluated.  The main element that leads to the diagnosis is the protrusion of the amniotic sac through the cervix (prolapsed fetal membranes).

  •  Fetal fibronectin (fFN) test.  New studies have recommended the quantification of this glycoprotein in every symptomatic or asymptomatic woman with evidence of short cervix.. It is considered an effective biochemical investigation to use with the cervical length assessment.



The management of an incompetent cervix may include, according to current obstetrics guidelines:

  • Progesterone.  
    • The administration of progesterone is used as part of the management of patients with a history of premature baby and miscarriage.
  • Ultrasound.
    • Patients with a history of premature babies or miscarriage need close monitoring of the cervix length. The ultrasounds should be done every two weeks from week 16 until week 24 of pregnancy. If the cervix begins to open or becomes shorter a cerclage may be recommended.
  • Cervical Cerclage.
    • It is a surgical procedure practiced with the aim to prevent premature birth. During this procedure, the cervix is sutured closed with strong sutures. The sutures will be removed during the last month of pregnancy or during the labour if it occurs before. Sometimes the cerclage can be done as a  prophylactic procedure before week 14 of pregnancy. Cervical cerclage isn’t always the management of patient with history of premature birth and is not recommended for women with multiple pregnancies.


You can make an appointment with Dr Kenny on 07 3188 5000.

This article is written to be informative and does not substitute seeking a professional consultation from a medical professional.



  1. Incompetent cervix – signs and ultrasound.
  2. Perinatal Practice Guideline. Cervical Insufficiency and Cerclage.
  3. Manju Chandiramani, Andrew H Shennan. Cervical insufficiency: prediction, diagnosis and prevention.
  4. Measurement of cervical length for prediction of preterm birth


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