Rate of preterm delivery and latency period in asymptomatic patients undergoing cerclage for very short cervix ≤10.0 mm

BACKGROUND

In asymptomatic women with cervical length ≤10 mm, vaginal progesterone has a limited effect in reducing the rate of preterm delivery.

OBJECTIVE

This study aimed to estimate the rate of preterm delivery and mean latency period to delivery in asymptomatic women with no history of preterm delivery and a cervical length of ≤10.0 mm undergoing or not undergoing cerclage and who were not treated with vaginal progesterone.

STUDY DESIGN

This was a retrospective analysis of asymptomatic patients with singleton pregnancies and no history of preterm delivery with an incidental finding of a cervical length of ≤10.0 mm measured by transvaginal ultrasound during midtrimester scan. Of note, 56 patients (63.6%) underwent cerclage placement and 32 patients (36.4%) did not, none of them received vaginal progesterone. Patients with evidence of advanced dilation, prolapsing membranes, ruptured membranes, or positive signs of infection were not candidates for cerclage placement and were excluded from the analysis. Differences in the prevalence of preterm delivery, mean gestational age at delivery, and mean latency from very short cervix identification to delivery between the 2 groups were calculated. Associations between cerclage and preterm delivery adjusted for maternal characteristics and fetal weight were estimated.

RESULTS

The median gestational ages at the time of cervical length measurement were 20 6/7 weeks (interquartile range, 17 5/7 to 23 3/7) in the cerclage group and 21 5/7 weeks (interquartile range, 17 6/7 to 23 6/7) in the no-cerclage group (P=.02). No difference in cervical length was observed between patients who had a cerclage (5.9±3.1 mm) and those who did not have a cerclage (6.5±3.2 mm) (P=.4). The prevalence of preterm delivery in women with cerclage vs women without cerclage was as follows: PTD at <37 weeks of gestation (31/56 [55.3%] in the cerclage group vs 28/32 [87.5%] in the no-cerclage group; adjusted odds ratio, 0.17; 95% confidence interval, 0.05–0.62; P=.008), PTD at ≤34 weeks of gestation (27/56 [48.2%] in the cerclage group vs 24/32 [75.0%] in the no-cerclage group; adjusted odds ratio, 0.16; 95% confidence interval, 0.05–0.55; P=.02), and PTD at ≤28 weeks of gestation (19/56 [33.9%] in the cerclage group vs 22/32 [68.7%] in the no-cerclage group; adjusted odds ratio, 0.15; 95% confidence interval, 0.05–0.51; P=.002). The median gestational ages at delivery were 32 6/7 weeks (interquartile range, 19 1/7 to 40 1/7) in the cerclage group and 28 1/7 weeks (interquartile range, 20 1/7 to 40 2/7) in the no-cerclage group (P=.001). The median latencies from the time of cervical length measurement to delivery were 84 days (interquartile range, 8–144) in the cerclage group and 43 days (interquartile range, 1–146) in the no-cerclage group (P=.003).

CONCLUSION

Among low-risk asymptomatic women with a very short cervix (≤10.0 mm) in the midtrimester of pregnancy, women treated with cerclage have an increased latency to delivery and a lower prevalence of preterm delivery than those treated with expectant management.