Prior Uterine Evacuation and the Risk of Short Cervical Length: A Retrospective Cohort Study.

Objectives: To determine whether a prior uterine evacuation procedure is associated with an increased risk of short cervical length (≤20 mm) in women without prior spontaneous preterm birth.

Methods: This work was a retrospective cohort study from January 2012 to December 2014 of singletons without prior spontaneous preterm birth with cervical length screening between 18 weeks and 23 weeks 6 days. Women with a prior miscarriage/abortion were excluded if management (medical, surgical, or expectant) was not specified. Prior uterine evacuation was defined as dilation and curettage or dilation and evacuation of a spontaneous or induced abortion. The primary outcome was the risk of short cervical length (≤20 mm) among women with and without 1 of more prior uterine evacuations at any gestational age, assessed by the odds ratio and adjusted odds ratio for confounders.

Results: Of 2672 women included, 714 (27%) had at least 1 prior uterine evacuation. The overall incidence of short cervical length in the cohort was 1% (n = 27). Women with at least 1 prior uterine evacuation were more likely to be African American (64% versus 41%; P < .001), smoke (14% versus 8%; P < .001), have a higher body mass index (mean ± SD, 28.1 ± 7.1 versus 26.8 ± 7.1 kg/m ; P < .001), and have had prior full-term delivery (60% versus 41%; P < .001). Women with at least 1 prior uterine evacuation had a significantly higher incidence of short cervical length (2% versus 0.7%; P = .003; odds ratio, 2.99 [95% confidence interval, 1.40-6.40]). After adjustment for confounders, prior uterine evacuation remained a source of increased risk of short cervical length (adjusted odds ratio, 2.63 [95% confidence interval, 1.19-5.80]).

Conclusions: Although the overall incidence of short cervical length is low (1%-2%), women with at least 1 prior uterine evacuation have at least a 2-fold increased risk of a short second-trimester cervical length compared to women without a prior uterine evacuation.