Cervical weakness

Risk factors for premature birth or stillbirth due to cervical weakness include: • diagnosis of cervical weakness in a previous pregnancy • previous preterm premature rupture of membranes • history of conization (cervical biopsy) • diethylstilbestrol exposure, which can cause anatomical defects, and • uterine anomalies ==Diagnosis==

Diagnosis of cervical weakness can be challenging and is based on a history of painless cervical dilation usually after the first trimester without contractions or labor and in the absence of other clear pathology. In addition to history, some providers use assessment of cervical length in second trimester to identify cervical shortening using ultrasound. However, short cervical length has actually been shown to be a marker of preterm birth rather than cervical weakness. Other diagnostic tests that have been suggested which have not been validated include hysterosalpingography and radiographic imaging of balloon traction on the cervix, assessment of the patulous cervix with Hegar or Pratt dilators, the use of a balloon elastance test, and use of graduated cervical dilators to calculate a cervical resistance index. • Less than 25 mm; 18% risk of preterm birth • Less than 20 mm; 25% risk of preterm birth • Less than 15 mm; 50% risk of preterm birth ==Treatment==

Cervical weakness is not generally treated except when it appears to threaten a pregnancy. Cervical weakness can be treated using cervical cerclage, a surgical technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal. Cerclage procedures usually entail closing the cervix through the vagina with the aid of a speculum. Another approach involves performing the cerclage through an abdominal incision. Transabdominal cerclage of the cervix makes it possible to place the stitch exactly at the level that is needed. It can be carried out when the cervix is very short, effaced or totally distorted. Cerclages are usually performed between weeks 12 to 14 of the pregnancy. As cerclage can induce preterm contractions without preventing premature delivery, makes the recommendation that it be used sparingly in women with a history of conization. A cervical pessary is being studied as an alternative to cervical cerclage since there are fewer potential complications. A silicone ring is placed at the opening to the cervix early in the pregnancy, and removed later in the pregnancy prior to the time of expected delivery. Further study is needed to determine whether a cervical pessary is equal or superior to current management. == Notes ==