Cervical incompetence
Encyclopedia
Cervical incompetence is a medical condition in which a pregnant
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

 woman's cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...

 begins to dilate
Cervical dilation
Cervical dilation is the opening of the cervix, the entrance to the uterus, during childbirth, miscarriage, induced abortion, or gynecological surgery...

 (widen) and efface
Effacement
Cervical effacement refers to a thinning of the cervix. It is a component of the Bishop score.It can be expressed as a percent.Prior to effacement, the cervix is like a long bottleneck, usually about four centimeters in length. Throughout pregnancy, the cervix is tightly closed and protected by a...

 (thin) before her pregnancy has reached term. Internal os opening more than 1 cm is abnormal and cervical length less than 2 cm is considered diagnostic. Cervical incompetence may cause miscarriage
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...

 or preterm birth during the second and third trimesters.

In a woman with cervical incompetence, dilation and effacement of the cervix may occur without pain or uterine contractions. In a normal pregnancy, dilation and effacement occurs in response to uterine contractions. Cervical incompetence occurs because of weakness of the cervix, which is made 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.

According to statistics provided by the Mayo Clinic
Mayo Clinic
Mayo Clinic is a not-for-profit medical practice and medical research group specializing in treating difficult patients . Patients are referred to Mayo Clinic from across the U.S. and the world, and it is known for innovative and effective treatments. Mayo Clinic is known for being at the top of...

, cervical incompetence is relatively rare in the United States, occurring in only 1—2% of all pregnancies, but it is thought to cause as many as 20—25% of miscarriages in the second trimester.

The condition can be diagnosed with a hysterosalpingogram or pediatric Foley catheter
Foley catheter
A Foley catheter is a flexible tube that is often passed through the urethra and into the bladder. The tube has two separated channels, or lumens, running down its length. One lumen is open at both ends, and allows urine to drain out into a collection bag...

.

Risk factors

Risk factors for premature birth or stillbirth due to cervical incompetence include:
  • diagnosis of cervical incompetence in a previous pregnancy,
  • previous preterm premature rupture of membranes,
  • history of conization (cervical biopsy),
  • diethylstilbestrol
    Diethylstilbestrol
    Diethylstilbestrol is a synthetic nonsteroidal estrogen that was first synthesized in 1938. Human exposure to DES occurred through diverse sources, such as dietary ingestion from supplemented cattle feed and medical treatment for certain conditions, including breast and prostate cancers...

     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
Physical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...

 to the cervix can weaken the tissues involved.

Treatment

Cervical incompetence is not generally treated except when it appears to threaten a pregnancy. Cervical incompetence can be treated using cervical cerclage
Cervical cerclage
Cervical cerclage , also known as a cervical stitch, is used for the treatment of cervical incompetence , a condition where the cervix has become slightly open and there is a risk of miscarriage because it may not remain closed throughout pregnancy...

, a surgical 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
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...

 with the aid of a speculum
Speculum
The term speculum, Latin for "mirror", and its plural specula, may refer to:* Speculum , a medical tool used for examining body cavities* Speculum , a journal of medieval studies published by the Medieval Academy of America...

. 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 14 and 16 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 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 the study where performing cerclage was compared to not having it performed. 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.
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