Cervical cerclage for the woman with prior adverse pregnancy outcome

Q. A 19-year-old patient (gravida 2, para 1) at 12 weeks' gestation had a preterm birth at 23 weeks in her last pregnancy. Her delivery was preceded by spontaneous rupture of the membranes and a brief period of irregular contractions. What information would be helpful to determine whether cervical insufficiency played a role in her prior pregnancy outcome? Placental pathology revealed no evidence of acute chorioamnionitis or abruption.

A. Although the American College of Obstetricians and Gynecologists (ACOG) defines cervical insufficiency as "the inability of the uterine cervix to retain a pregnancy to term," this diagnosis is often difficult to make.¹ Typically, cervical insufficiency is diagnosed after recurrent midpregnancy deliveries without presenting contractions, membrane rupture, or infection. The women presenting often recall symptoms of vague pelvic pressure, cramping, or increased discharge before delivery. Some present with a typical history of painless dilation resulting in fetal membrane prolapse and subsequent delivery without contractions in the late second or early third trimester.

In the case described here, it would be difficult to argue against the diagnosis of cervical insufficiency in spite of the fact that this woman's history does not meet rigid diagnostic criteria, especially if, in the previous pregnancy, she had presented in the second trimester with asymptomatic membrane prolapse without contractions or bleeding, if she had had an amniocentesis that revealed no evident infection, and if she had had a successful cerclage placement resulting in an at-term pregnancy. In this case, as in most cases, the history is not straightforward and the diagnosis remains unclear until there have been several early preterm births (PTBs).

Some women carry 1 or more pregnancies to term and then present with a typical picture of cervical insufficiency. Under this circumstance, the possibility of unrecognized cervical lacerations from the prior delivery should be considered.

If the patient in the example had presented with a suspicious history before becoming pregnant, several evaluations could have been helpful. Clinical examination could have revealed the presence of cervical lacerations or urogenital abnormalities (eg, vaginal septum or duplication or duplicate cervix) that might have suggested an upper-tract abnormality. An ultrasound may have revealed duplication of the uterine corpus. Hysterosonography (possibly done as 3D sonohysterogram), hysterosalpingogram, or hysteroscopy could have identified abnormalities of the uterine cavity.

The patient in this scenario does not meet current ACOG criteria for cervical insufficiency because she has not experienced recurrent pregnancy losses.¹ Since the current ACOG definition of cervical insufficiency requires multiple pregnancy losses, some obstetricians have advocated that transvaginal ultrasound (TVU) cervical length (CL) could be used to aid in the diagnosis of this condition. The presence of both: one or more prior early PTBs and/or second-trimester losses, and TVU CL less than 25 mm or cervical dilatation (eg, ≥1 cm) on digital examination before 24 weeks in the current pregnancy may arouse suspicion of cervical insufficiency. In fact, the practice of cerclage, the classic intervention for cervical insufficiency, originated as a treatment for women with both prior early PTBs and second-trimester cervical changes.^3,4