Using a cervical pessary to prevent preterm birth

Giving birth before term contributes to more than half of the deaths of newborn babies. Weakness of the cervix (the neck of the womb) and multiple pregnancy are common risk factors. Different management techniques have been tried including tightening the cervix with a stitch (cervical cerclage) to prevent its premature opening. Although it is a simple operation, cervical cerclage is invasive requiring anaesthesia and can have bleeding complications and cause infection and pregnancy loss. There is also controversy regarding the efficacy of cervical cerclage and the women who benefit most from this operation. Closing the cervix with a silicone ring (cervical pessary) that is removed at around 37 weeks is a simple, less invasive procedure that does not require anaesthesia and might replace the cervical stitch operation. To date, data obtained from one well-designed randomised clinical trial suggest that inserting a cervical pessary is superior to expectant management in the prevention of preterm birth in 385 women between 18 and 22 weeks of pregnancy. Neonatal paediatric care admission was reduced in the pessary group in comparison to the expectant group. These women had a singleton pregnancy and high risk of preterm birth because of the short length of the neck of the womb (cervix). Among the pessary group, 27 women needed pessary repositioning without removal and there was one case of pessary removal. Results of both the randomised trial and non-randomised trials show that pessary users complained of increased vaginal discharge. More studies are needed in different settings, with singleton and multiple pregnancies where the weakness of the cervix is from other causes, to confirm the results of the single trial included in this review. Some studies are ongoing.

Authors' conclusions: 

The review included only one well-designed randomised clinical trial that showed beneficial effect of cervical pessary in reducing preterm birth in women with a short cervix. There is a need for more trials in different settings (developed and developing countries), and with different risk factors including multiple pregnancy.

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Background: 

Preterm birth is a major health problem and contributes to more than 50% of the overall perinatal mortality. Preterm birth has multiple risk factors including cervical incompetence and multiple pregnancy. Different management strategies have been tried to prevent preterm birth, including cervical cerclage. Cervical cerclage is an invasive technique that needs anaesthesia and may be associated with complications. Moreover, there is still controversy regarding the efficacy and the group of patients that could benefit from this operation. Cervical pessary has been tried as a simple, non-invasive alternative that might replace the above invasive cervical stitch operation to prevent preterm birth.

Objectives: 

To evaluate the efficacy of cervical pessary for the prevention of preterm birth in women with risk factors for cervical incompetence.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 September 2012), Current Controlled Trials and the Australian New Zealand Clinical Trials Registry (1 September 2012).

Selection criteria: 

We selected all published and unpublished randomised clinical trials comparing the use of cervical pessary with cervical cerclage or expectant management for prevention of preterm birth. We did not include quasi-randomised trials. Cluster-randomised or cross-over trials were not eligible for inclusion.

Data collection and analysis: 

Two review authors independently assessed trials for inclusion.

Main results: 

The review included one randomised controlled trial. The study included 385 pregnant women with a short cervix of 25 mm or less who were between 18 to 22 weeks of pregnancy. The use of cervical pessary (192 women) was associated with a statistically significantly decrease in the incidence of spontaneous preterm birth less than 37 weeks' gestation compared with expectant management (22% versus 59 %; respectively, risk ratio (RR) 0.36, 95% confidence interval (CI) 0.27 to 0.49). Spontaneous preterm birth before 34 weeks was statistically significantly reduced in the pessary group (6% and 27% respectively, RR 0.24; 95% CI 0.13 to 0.43). Mean gestational age at delivery was 37.7 + 2 weeks in the pessary group and 34.9 + 4 weeks in the expectant group. Women in the pessary group used less tocolytics (RR 0.63; 95% CI 0.50 to 0.81) and corticosteroids (RR 0.66; 95% CI 0.54 to 0.81) than the expectant group. Vaginal discharge was more common in the pessary group (RR 2.18; 95% CI 1.87 to 2.54). Among the pessary group, 27 women needed pessary repositioning without removal and there was one case of pessary removal. Ninety-five per cent of women in the pessary group would recommend this intervention to other people. Neonatal paediatric care admission was reduced in the pessary group in comparison to the expectant group (RR 0.17; 95% CI 0.07 to 0.42).

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