Cervical weakness, also called cervical incompetence or cervical insufficiency, is a medical condition of

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...

in which the

cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes durin ...

begins to dilate (widen) and efface (thin) before the pregnancy has reached term. Definitions of cervical weakness vary, but one that is frequently used is the inability of the uterine cervix to retain a pregnancy in the absence of the signs and symptoms of clinical contractions, or labor, or both in the second trimester. Cervical weakness may cause

miscarriage Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical ...

preterm birth Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is betwee ...

during the second and third trimesters. It has been estimated that cervical insufficiency complicates about 1% of pregnancies, and that it is a cause in about 8% of women with second trimester

recurrent miscarriage Recurrent miscarriage is three or more consecutive pregnancy losses. In contrast, infertility is the inability to conceive. In many cases the cause of RPL is unknown. After three or more losses, a thorough evaluation is recommended by American So ...

s. A sign of cervical weakness is ''funneling'' at the internal orifice of the uterus, which is a dilation of the cervical canal at this location. In cases of cervical weakness, dilation and effacement of the cervix may occur without pain or

uterine contraction Uterine contractions are muscle contractions of the uterine smooth muscle that occur during the menstrual cycle and labour. Uterine contractions occur throughout the menstrual cycle in the non-pregnant state and throughout gestation. Throughout ...

s. In a normal pregnancy, dilation and effacement occurs in response to uterine contractions. Cervical weakness becomes a problem when the cervix is pushed to open by the growing pressure in the uterus as pregnancy progresses. If the responses are not halted, rupture of the membranes and birth of a premature baby can result. The older terminology is perceived as blaming the woman for the miscarriage, as if she were an incompetent or insufficient person. Consequently, ''cervical weakness'' is the recommended term.

Risk factors

Risk factors for premature birth or stillbirth due to cervical weakness include: * diagnosis of cervical weakness in a previous pregnancy * previous preterm premature rupture of membranes * history of conization (cervical biopsy) *

diethylstilbestrol Diethylstilbestrol (DES), also known as stilbestrol or stilboestrol, is a nonsteroidal estrogen medication, which is presently rarely used. In the past, it was widely used for a variety of indications, including pregnancy support for those with a ...

exposure, which can cause anatomical defects, and * uterine anomalies Repeated procedures (such as mechanical dilation, especially during late pregnancy) appear to create a risk. Additionally, any significant trauma to the cervix can weaken the tissues involved.

Diagnosis

Diagnosis of cervical weakness can be challenging and is based on a history of painless cervical dilation usually after the first trimester without contractions or labor and in the absence of other clear pathology. In addition to history, some providers use assessment of cervical length in second trimester to identify cervical shortening using ultrasound. However, short cervical length has actually been shown to be a marker of

rather than cervical weakness. Other diagnostic tests that have been suggested which have not been validated include hysterosalpingography and radiographic imaging of balloon traction on the cervix, assessment of the patulous cervix with Hegar or Pratt dilators, the use of a balloon elastance test, and use of graduated cervical dilators to calculate a cervical resistance index. Normally, the cervix should be at least 30 mm in length. Cervical weakness is variably defined. However, a common definition is a cervical length of less than 25 mm at or before 24 weeks of gestational age. The risk of preterm birth is inversely proportional to cervical length: *Less than 25 mm; 18% risk of preterm birth *Less than 20 mm; 25% risk of preterm birth *Less than 15 mm; 50% risk of preterm birth

Treatment

Cervical weakness is not generally treated except when it appears to threaten a pregnancy. Cervical weakness can be treated using cervical cerclage, a

surgical Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pa ...

technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal. Cerclage procedures usually entail closing the cervix through the

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hy ...

with the aid of a speculum. Another approach involves performing the cerclage through an abdominal incision. Transabdominal cerclage of the cervix makes it possible to place the stitch exactly at the level that is needed. It can be carried out when the cervix is very short, effaced or totally distorted. Cerclages are usually performed between weeks 12 to 14 of the pregnancy. The sutures are removed between weeks 36 and 38 to avoid problems during labor. The complications described in the literature have been rare:

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

from damage to the veins at the time of the procedure; and fetal death due to uterine vessels occlusion. No significant differences in pregnancy outcomes were found in a study evaluating pregnancy outcomes after cervical conization. This study suggests for women with cervical insufficiency due to prior cone biopsy, cerclage is not superior to no intervention. As cerclage can induce preterm contractions without preventing premature delivery, makes the recommendation that it be used sparingly in women with a history of conization. A cervical pessary is being studied as an alternative to cervical cerclage since there are fewer potential complications. A silicone ring is placed at the opening to the cervix early in the pregnancy, and removed later in the pregnancy prior to the time of expected delivery. Further study is needed to determine whether a cervical pessary is equal or superiour to current management.

Notes

References

* The first revision of this article was adapted from material from the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, ...

source "Summary Report: ICD-9-CM coordination and maintenance committee", published at https://web.archive.org/web/20051223102344/http://www.cms.hhs.gov/paymentsystems/icd9/icd111700.pdf.

External links

{{Diseases of the pelvis and genitals Noninflammatory disorders of female genital tract Health issues in pregnancy Miscarriage