Short Cervix

Definition - What does Short Cervix mean?

During pregnancy, the cervix is considered to be very short if it measures less than 20 mm before 24 weeks. The cervix is a canal that sits at the lower end of the uterus and is the passageway that connects the uterus to the vagina. During pregnancy, the cervix remains closed and firm acting as a barrier to infection and supporting the weight of the developing fetus.

The cervix normally measures between 35-48 mm in length with a short cervix measuring less than 25 mm long before 24 weeks of pregnancy. Because the cervix helps hold the fetus inside the uterus, if the cervix shortens prematurely, the risk of preterm labor and delivery increases the shorter the cervix measures before 24 weeks.

Cervix length can be estimated by a pelvic exam or measured by transvaginal ultrasound. If a cervix is determined to be short there are several treatment options including progesterone, a pessary, or cerclage—stitching the cervix closed until delivery.

FertilitySmarts explains Short Cervix

Normally, around 32 weeks of pregnancy the cervix begins to prepare for labor and delivery by softening, thinning, and becoming shorter in length. If this process occurs before early, before 24 weeks of pregnancy, the shortened cervix may not be able to bear the weight of the developing fetus and the risk for preterm labor increases.

Experiencing symptoms of preterm labor including a constant low, dull backache, vaginal spotting, or pelvic pressure, may prompt an examination of the cervix. While a pelvic exam can provide an estimate of cervix length, a transvaginal ultrasound determines a more precise measurement. The transvaginal ultrasound is generally performed with an empty bladder and measures the length of the cervix from the internal opening on the inside of the uterus to the external opening inside of the vagina.

Factors in pregnancy including the timing of a shortening cervix, history of preterm labor, and the presence of active labor generally guide treatment decisions. Hormonal progesterone or a device called a pessary may be used to support the cervix. In some cases, especially if the cervix is shortened during the second trimester, a cerclage may be used which involves stitching the cervix closed until labor and delivery would be less risky.

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