The Cervix During Pregnancy
During pregnancy the
cervix is blocked by a special antibacterial mucosal plug which prevents
infection, somewhat similar to its state during the infertile portion of the
menstrual cycle. The mucus plug comes out as the cervix dilates in labor or
shortly before. One of the most common problems with the
cervix during pregnancy is an incompetent cervix.
Incompetent Cervix and Pregnancy
An incompetent cervix
is one that undergoes abnormal widening during pregnancy. In a normal
pregnancy, the cervix remains tightly closed until the pregnancy comes
to term, at which point the cervix widens due to uterine contractions.
An incompetent cervix thins and widens prematurely, usually between the
third and thirteenth week of pregnancy.
Without treatment, an incompetent cervix can result in miscarriages or
premature delivery and an increased risk of infection. The condition can
be treated with bed rest, medication and cervical
cerclage surgery. Incompetent
cervix accounts for up to 25 percent of all second trimester
miscarriages.
Causes
and Risks of Incompetent Cervix
A number of risk factors can cause an incompetent
cervix. Cervical cancer biopsies often contribute to an incompetent
cervix. Cervical cancer "cone biopsies" are used as a cervical cancer
screening tool. Treatment of cervical cancer can cause cervical trauma,
damaging the cervix and making an incompetent cervix more likely.
In addition to cervical cancer, any form of cervical trauma
or surgery increases the risk of an incompetent cervix during pregnancy.
Artificial cervical dilation during an abortion can sometimes damage the
cervix.
Other factors that contribute to an incompetent cervix
include a history of miscarriages in previous pregnancies, physical cervical
abnormalities and cervical birth defects. Women whose mothers took
diethylstilbestrol (DES) during pregnancy have an increased risk of an
incompetent cervix and miscarriage. DES was prescribed to prevent
miscarriage, but was found to cause cervical defects.
In some cases, a pregnancy ends with miscarriage due to a
spontaneous incompetent cervix, and no reason for the condition can be
found. A future pregnancy has a high chance of developing an incompetent
cervix without precautionary treatment to prevent cervical widening.
Diagnosing Incompetent Cervix
An incompetent cervix can be treated if diagnosed early
enough. The cervical widening is usually painless. Regular prenatal
checkups can detect cervical widening.
An incompetent cervix may cause vaginal spotting and
bleeding. Any spotting during pregnancy should be reported to your doctor,
no matter what the underlying cause. If not detected soon enough, cervical
widening eventually causes premature amniotic membrane rupture (when the
"waters" break), starting labor and usually resulting in fetal death.
Incompetent Cervix Treatment: Cerclage
Once an incompetent cervix is diagnosed, treatment may
prevent a premature end to the pregnancy. The later in pregnancy an
incompetent cervix develops, the better the chances of a successful
pregnancy.
Medication may be advised to relax the uterus and prevent
premature labor. However, the most successful treatment for an incompetent
cervix is a surgical technique known as
cervical cerclage.
Cervical cerclage stitches the cervix shut, preventing
further cervical widening and lowering the chance of miscarriage. The
cerclage stitches stay in place until the pregnancy comes to term, at which
point the cerclage stitches are removed.
Cervical cerclage is most often recommended between the
fourteenth and sixteenth weeks of pregnancy. After cervical cerclage, bed
rest is recommended for a full 24 hours. After this point, exercise should
be limited for the remainder of the pregnancy. Plenty of rest is
recommended, and sexual intercourse should be avoided until the end of the
pregnancy.
Cervical cerclage has a high success rate: between eighty to
ninety percent of women who undergo the procedure deliver healthy babies.
Cerclage works best when performed early in pregnancy, so prompt diagnosis
of an incompetent cervix is essential. Consult your doctor about cervical
cerclage if you have a history of incompetent cervix.
The cervix may be imaged with a vaginal ultrasound.
Click the picture to see a video of a vaginal
ultrasound.
