A Randomized Controlled Trial of Cervical Scanning vs History to Determine Cerclage in Women at High Risk of Preterm Birth (CIRCLE Trial)

Abstract

Cervical cerclage may be useful either as a preventative or therapeutic measure in women at risk for preterm delivery (PTD). The 2 common types of management currently used in pregnant women at high risk of PTD are transvaginal measurement of cervical length, or assessment of risk and need for intervention based on obstetric history. Because the RR of a preterm birth increases with shortening cervical length, ultrasound measurement of cervical length in a woman with a previous preterm birth could help target those needing cerclage. Currently, history-indicated cerclage is inserted only in women with prior multiple pregnancy losses. Suggestions have been made that identification of the ultrasono-graphically short cervix with cerclage may reduce the need for a cerclage based on a history of only 1 previous PTD. This randomized controlled trial compared use of ultrasound-indicated cervical cerclage in pregnant women with a short cervix (<20 mm in length), with elective management without ultrasound in which the decision to insert a prophylactic history-indicated suture was based solely on obstetric history. Eligible pregnant women were enrolled in the study between 2003 and 2006 from hospitals in the United Kingdom. The study subjects were asymptomatic women at high risk, who had at least 1 previous delivery between 16 and 34 weeks. Of the eligible 248 women, 123 were randomized to the ultrasound scanning group and 125 to history-indicated management group. The primary outcome measure was PTD before 34 weeks. There was no difference between the 2 groups in the incidence of preterm birth between 24 and 34 weeks of gestation (19/125 [15%] in the history-indicated management group vs 18/122 [15%] in the ultrasound scanning group); the relative risk [RR] was 0.97, with a 95% confidence interval (CI) of 0.54 to 1.76. Women in the ultrasound scanning group were significantly more likely than those in the history-indicated management group to receive a cerclage (32% vs 19%; RR, 1.66; 95% CI, 1.07-2.47) or progesterone (39% vs 25%; RR, 1.55; 95% CI, 1.06-2.25). These data suggest that the decision on placement of cervical cerclage in a women with a previous preterm birth should be made on the basis of clinical history, not on the basis of ultrasound scanning. However, the data do not support routine placement of history-indicated sutures routinely in this population. Scanning may still be beneficial in women at higher risk.