Cervical Length

Definition - What does Cervical Length mean?

Cervical length refers to the length of the narrow, lower portion of the uterus called cervix. Normally, the cervix is long, measuring about 4 to 5 cm. During pregnancy, the average cervical length becomes about 3.5 cm. Sometimes, however, the cervix begins to shorten to less than 2.5 cm quite earlier before the baby is due to be born. This short cervix is not capable of holding the baby and thus poses the risk of premature labor and delivery before term. The shorter the cervical length, the higher is the risk of spontaneous premature birth (i.e. delivery before the normal 37 weeks of pregnancy).

FertilitySmarts explains Cervical Length

What can cause the cervical length to shorten during pregnancy? Sometimes, the cervix becomes incompetent or starts to open long before the baby is ready to be delivered. This condition, known as insufficient or incompetent cervix, causes the cervix to shorten, and lead to premature birth. An incompetent cervix is too weak to handle the pressure of the growing baby, and can also result in the loss of a pregnancy. Whether an incompetent cervix will lead to premature delivery or a pregnancy loss depends on the timing of delivery, with earlier birth more likely resulting in a miscarriage.

The cervical length is typically determined during an ultrasound exam. Measured by ultrasound in high-risk pregnant womenwithout any symptoms, the cervical length can predict spontaneous premature birth in less than 35 weeks. Also noted, is the funneling of the cervix — the cervix changes its shape from a "v"-shaped organ to a "u" shape due to the widening of the internal part of the cervical canal and the shortened cervical length. When the ultrasound shows short cervix, the following treatments can be offered:

  • Cervical cerclage, or a cervical stitch, is stitching the cervix to keep it closed, thus preventing either a late miscarriage or premature birth.
  • A cervical pessary is a silicone device inserted into the cervix to maintain cervical closure. Placing a cervical pessary is a non-invasive route to prolong the pregnancy in pregnant women with a short cervix.
  • Progesterone is a hormonal medication that keeps the uterus from having contractions. When inserted into the vagina, progesterone is as effective as cervical cerclage in preventing premature birth in women with a short cervical length.
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