What is a Shortened Cervix?

A shortened cervix, also known as cervical insufficiency, is a condition where the canal between the uterus and vagina measures less than 1 inch (2.5 cm) at 24 weeks of pregnancy. The cervix usually maintains its thickness and stretches out during the third trimester to prepare for dilation and birth. This condition can lead to gestational complications, preterm birth and possibly miscarriage. Treatments for a shortened cervix depend on the severity of the insufficiency.

During pregnancy, the cervix typically measures 1.2 to 1.4 inches (3 to 3.5 cm) at 24 weeks of pregnancy and stretches thinner as the women approaches the end of gestation. A shortened cervix can become stressed under the load of the baby and amniotic fluid, and it might become dilated prematurely. This is a common cause of miscarriage during the second trimester and might lead to preterm labor in the third trimester.

Doctors are unsure what causes cervical insufficiency, but some research points to cervical infection or improper nourishment as a possible culprit. The cervix might be shortened by procedures such as a loop electrical excision procedure (LEEP) or damage caused by terminating previous pregnancies. Women who have had previous miscarriages or preterm deliveries should undergo testing to determine whether they have this condition.

For many years, it was difficult to determine whether a woman suffered from a shortened cervix, but this condition can be detected with a transuterine ultrasound. Women who have been diagnosed with cervical insufficiency should consult with obstetricians who specialize in high-risk pregnancy. A shortened cervix should be treated as an indicator of possible preterm birth, not a guarantee of early labor.

Doctors determine the best course of action depending on the severity of cervical shortness at a particular point in gestation. If a woman presents with a cervix slightly shorter than typical, a doctor might recommend that she continue her normal activities with a reduction in load-bearing. Moderate shortness usually is treated with bed rest and further observation. In the most severe cases, a shortened cervix might be treated with a procedure called cerclage to add support to the cervix.

A cervical cerclage is an outpatient procedure in which the obstetrician stitches the cervix closed to prevent preterm labor. The procedure is usually done after 12 weeks of pregnancy, and the stitches remain in place until 37 weeks of gestation or until the woman's water breaks and labor begins. The cerclage procedure is risky and typically is done only in extreme cases of a shortened cervix. There is a chance that this treatment could cause infection, contractions or rupture in cervical membranes.