What is the length of the cervix indicates the likelihood of premature birth

What is the length of the cervix indicates the likelihood of premature birth

Cervicometry during pregnancy – what is it

Cervicometry – technique of transvaginal ultrasound, which measures the length of the cervix. When the cervix is ​​very short, there is an increased risk of premature birth. How cervicometry is done and in which cases the study is indicated will be discussed below.

Norms for the length of the cervix by weeks of pregnancy

Cervicometry during pregnancy – what is this This is the most reliable way to measure the length of the closed part of the cervix. The transvaginal ultrasound technique exceeds the accuracy of the transabdominal method of determining the length of the cervix. Cervicometry is performed on all pregnant women, but for women with a history of premature birth, the results of the study are especially important. Cervicometry is indicated for these patients every 15 days in the interval from 14 to 24 weeks of pregnancy. Other pregnant women are recommended to have a one-time examination at 20-24 weeks. The procedure is absolutely safe for the mother and the fetus and practically does not differ from a standard ultrasound examination.

Norms for the length of the cervix by weeks of pregnancy:

  • 16-20 week: 40-45 mm;
  • 25-28 week: 35-40 mm;
  • 32-36 week: 30-35 mm.

If the length of the cervix is ​​30 mm or more, the probability of premature birth does not exceed the general population rate. What length of the cervix signals a high risk of premature birth? When a shortened cervix (less than 15 mm) is detected, urgent hospitalization and a set of measures to prevent premature birth (cervical cerclage, progesterone administration) are indicated.

If, according to the results of cervicometry, the length of the cervix is ​​less than 25 mm, the patient is given the conclusion "ECHO-signs of ICN". with the recommendation of obstetrician-gynecologist consultation.

Cervicometry: preparation and technique

Before the examination, the bladder should be emptied. Cervicometry is performed in the lithotomy position (the woman lies on her back with bent knees). The doctor carefully inserts the ultrasound probe into the vagina towards the anterior vault. At the same time, they acquire a sagittal view of the organ. The mucous membrane of the endocervix serves as a reference point for determining the position of the internal pharynx. The doctor measures the closed part of the cervix, starting from the external pharynx to the V-shaped notch of the internal pharynx. This ends the study and the patient is given a conclusion.

Transvaginal cervicometry can detect a number of important clinical conditions, ranging from premature labor to polyhydramnios (polyhydramnios). Detection of a short cervix by transvaginal ultrasound at 18-24 weeks of pregnancy is the most important prognostic parameter of spontaneous premature birth. If the length of the cervix at 14-24 weeks of pregnancy is less than 15 mm, then there is a 50% chance of preterm birth up to 33 weeks of pregnancy. In women with a previous adverse history, a pattern is observed: the shorter the cervix, the more likely recurrent premature births are, and with a length of less than 10 mm, the degree of probability increases to 90%. That is why it is so important to see a gynecologist during pregnancy and to conduct transvaginal cervicometry in a timely manner.

The price of ultrasound cervicometry can be found out on our site.

Updated: 06.04.2025
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