The length of the cervix during pregnancy – table of norms by week, prognosis

December 29, 2021 Adam 0 Comments

The cervix is not just an entrance to the uterine cavity. The elastic and elastic neck (the cervical canal in it) protects the developing fetus from infections and, tightly closing, holds it until the moment of delivery. Normally, the cervix is closed, but it softens and opens slightly by 37 weeks, when the woman’s body is being prepared for childbirth.

The content of the article:

Short cervix – diagnosis and risks at different stages of pregnancy

Unfortunately, pregnancy does not always go smoothly and without problems. A very common cause of miscarriage and spontaneous abortion or premature birth is a pathologically short cervix, or isthmic-cervical insufficiency.

The reasons that cause this pathology –

Progesterone deficiency.
Injuries to the cervix after surgery, conization, abortion or previous childbirth.
Changes in the structure of the cervical tissue as a result of hormonal changes in the body.
Psychogenic factors – fears and stress.
Infectious and inflammatory diseases of the pelvic organs and directly – of the uterus and cervix, which lead to tissue deformation and scarring.
Changes caused by uterine bleeding.
Individual anatomical and physiological characteristics of the organism of the expectant mother.

Measuring the length of the cervix during pregnancy is very important, because this will allow time to identify pathology and take measures to prevent miscarriage.

As a rule, ICI is accurately diagnosed in the second half of pregnancy, when the fetus is already large.

At the gynecological examination of the future mother, the obstetrician-gynecologist assesses the condition of the cervix, the size of the external pharynx, the presence and nature of the discharge. Normally, the cervix in the first weeks of pregnancy is dense, has a posterior deviation, the external pharynx is closed and does not allow a finger to pass through.
To diagnose a pathologically shortened cervix, ultrasound is prescribed (with a transvaginal sensor – in early pregnancy, transabdominal – in the second half of pregnancy). On the study, cervicometry is performed, that is, the measurement of the length of the cervix. According to the data obtained, the question of methods that will help preserve the pregnancy is being resolved – this is a suture on the cervix or the setting of an obstetric pessary.

The length of the cervix during pregnancy – table of norms by week

Norms of the length of the cervix can be recognized by the data in the table:

Gestational age	Length of the cervix (normal)
16 – 20 weeks	40 to 45 mm
25 – 28 weeks	35 to 40 mm
32 – 36 weeks	30 to 35 mm

On an ultrasound study, the degree of maturity of the cervix is also determined, the result is evaluated in points.

Table of signs of the degree of maturity of the cervix

Sign	Score 0	Score 1	Score 2
Cervical consistency	Dense structure	Soft, firm in the area of the internal pharynx	Soft
Neck length, its smoothness	More than 20 mm	10-20 mm	Less than 10 mm or smoothed
Cervical canal patency	Outer pharynx closed, skipping a fingertip	1 finger can pass into the cervical canal, but the internal pharynx is closed	2 or more fingers pass into the cervical canal (with a smoothed cervix)
Position of the cervix	Backwards	Forward	In the middle

Survey results are assessed in this way (the scores obtained are summed up):

0 to 3 points – immature cervix
4 to 6 points – insufficiently mature neck, or ripening
7 to 10 points – mature cervix

Until 37 weeks, the cervix is normal – immature, and passes into a mature state before childbirth. It should be noted that immaturity of the cervix in the last weeks of pregnancy – This is a pathology opposite to ICI, and it also needs monitoring and correction, up to the choice of the method of delivery by cesarean section.

If the length of the cervix is at the border of the norm, but at the same time there are signs of the onset of preterm labor, it is necessary to perform another ultrasound scan. Which will help to accurately diagnose ICI, if any.

Shortening of the cervix before childbirth – what to do and how to treat it?

A shortening of the cervix, diagnosed between 14 and 24 weeks, indicates a clear risk of premature birth and requires urgent correction.

If during this period the length of the cervix is less than 1 cm, the baby will be born at 32 weeks of gestation.
If from 1.5 to 1 cm, the baby will be born at 33 weeks of gestation.
The length of the cervix is less than 2 cm indicates that labor may take place at 34 weeks gestation.
Length of the cervix from 2.5 cm to 2 cm – a sign that the baby is likely to be born at 36 weeks of gestation.

If the expectant mother is diagnosed with a shortening of the cervix, then treatment will be offered, taking into account the degree of shortening and the duration of pregnancy:

Conservative therapy with tocolytic drugs, progesterone… Treatment is performed in a hospital.
Cerclage of the cervix, that is, suture. The stitches are removed before delivery.
Setting an obstetric pessary – a rubber uterine ring that relieves the cervix and eliminates its stretching.

The expectant mother can also be recommended:

Reduce physical activity. Avoid activities that put pressure on the abdominal area.
Refuse sex until childbirth.
Take natural sedatives – for example, tinctures of motherwort or valerian.
Take antispasmodic drugs prescribed by your doctor – for example, no-shpa, papaverine.

The shortening and softening of the cervix from week 37 is the norm that does not require treatment and correction.