Cervical Incompetence Evaluation and Management

Recurrent pregnancy loss is a challenging problem for clinicians because of the variety of factors associated with this disorder. Cervical incompetence (or insufficiency) is well-recognized as one such factor. Cervical insufficiency is believed to be based on the presence of painless cervical dilatation after the first trimester leading to expulsion of a well-formed and non-macerated fetus in the second trimester, typically before 24 weeks’ gestation. Although some cases of cervical insufficiency have been associated with congenital uterine anomalies, the majority of cases occur as a result of surgical trauma to the cervix. Infrequently it is a de novo finding Several methods that have been suggested to diagnose this condition. In the pre-pregnant state, hysterosalpingography, hysteroscopy, the use of Hegar or Pratt dilators and transvaginal ultrasonography have been used to check the integrity of the cervix. In the pregnant state, there is increasing reliance of the measurement of the cervical length and detection of progressive shortening and or dilatation of the internal os with funneling. Despite these approaches, there is a lack of consensus on the optimal diagnostic method and when intervention should be offered.

Nonsurgical management options such as bed rest and activity restriction have been suggested to reduce the likelihood of pregnancy loss with cervical insufficiency. However, there is no convincing evidence on the efficacy of such management. The use of the vaginal pessary has seen resurgence in interest especially with the introduction of the Arabin pessary with promising results in the prevention of preterm delivery. Surgical interventions involve the use of a cerclage procedure, which can be done vaginally or transabdominally (via a laparotomy or through the laparoscope). Although Shirodkar and McDonald cervical cerclage methods are popular, the superiority of one or the other has not yet been established. The transabdominal approach is generally reserved for those cases in which there are anatomical limitations to the transvaginal approach or in situations of previous failure of the transvaginal method.

The efficacy of the cerclage procedure can be improved by attention to several important aspects. First, it has been observed that the use of the Mesilene tape results in better outcomes than when using other types of suture. Second, the cervical height (i.e. length of cervix from the suture to the external os) is an important predictor of outcome; the longer the height the better the outcome. Clearly, the cerclage should be placed as high as possible. Third, it has been shown in a randomized trial that the insertion of two sutures is more efficacious that the traditional approach of inserting only one suture.

The increase in the numbers of multiple pregnancies has produced a higher prevalence of physiological cervical incompetence associated with the rapidly expanding uterus. Although, currently it is not recommended to use the cerclage procedure when cervical shortening is observed, clinical trials are underway to evaluate the efficacy of this intervention. It is important to recognize that the traditional cut-off value of cervical length of 2.5 cm below which a cerclage is indicated in singleton pregnancies needs to be re-evaluated in light of recent evidence demonstrating that the cut-off level for twins should be higher and is gestational age dependent (one recommendation is to consider intervention when the cervix length is <3.5cm at 20 weeks’ gestation).

Cervical insufficiency is an important factor associated with recurrent pregnancy loss. Selection of the ideal candidate for interventions with cerclage require consensus on the optimal diagnostic strategy and the intervention itself need to be standardized. The special case of the twin pregnancy needs further research for management to prevent pregnancy loss.