Courtesy of A.D.A.M

Although the cervix is supposed to hold a pregnancy until term things sometime go wrong.  Women can lose an otherwise healthy baby because of a weak or short cervix. When cervical tissue becomes weak, this condition is known as Cervical Insufficiency (CI) and affects approximately 0.1 to 2% of all pregnancies. Women who have a history of painless bleeding in the second trimester or complain of pelvic pressure followed by the delivery of a fetus most likely have CI. Also, women who have had three or more pregnancy losses in the second trimester have CI as well. Patients with these types of histories have traditionally been treated with a procedure called a cerclage. Think of a cerclage as a stitch in the cervix that keeps it closed so that the baby can continue to grow.

There are many reasons why women develop CI and include women who have a short cervix, collagen disorders, uterine abnormalities and cervical lacerations.  Some women are born with a short cervix while others acquire it because of surgical procedures such as a cone biopsy, LEEP (loop electrosurgical excision procedure) or laser ablation. Voluntary pregnancy terminations can also shorten the cervix and increase the risk for a preterm birth. The collagen disorder such as Ehlers-Danlos syndrome can so as well.

Can cervical insufficiency be diagnosed before pregnancy? Unfortunately not, however, the use of a patient’s history, physical exam and ultrasound can help tremendously. Visualization of membranes seen during a speculum exam is extremely suspicious for CI and requires a cerclage if the patient is less than 24 weeks.  Any cervical length of less than 15 mm is diagnostic of CI and requires a cerclage.

The average length of the cervix at 20 and 22 weeks is 40 mm; at 32 weeks it’s 35 mm. A woman who has a cervical length of less than 25 mm will most likely get a cerclage if she has a history of a three previous second trimester miscarriages. A woman less than 23 weeks with a cervical length of less than 25 mm might be offered a cerclage or progesterone treatment.

Part 2 of this article will discuss what happens if a woman without symptoms of preterm labor is found to have a cervical length less than 25 mm and when and where should the cerclage be removed? What lifestyle changes should be made with a cerclage?

Do you know how to anticipate and manage the unexpected events that could occur during your pregnancy? You will if you purchase The Smart Mother’s Guide to a Better Pregnancy available on or wherever books are sold.