Does Height Matter? The Association Between Cerclage Height and Pregnancy Outcome

Abstract

Abstract

Objective:

The aim of this research was to investigate if an association exists between cerclage height (CH) or the ratio of CH-to-cervical length (CL) and delivery prior to 35 weeks gestational age (GA) among patients having undergone cervical cerclage.

Materials and Methods:

A retrospective cohort study was performed examining transvaginal imaging and obstetric medical records data from 106 women who received prenatal care, had a cerclage placed, and delivered at a tertiary referral center in Cincinnati, OH, between July 2012 and December 2014. The primary outcome was delivery prior to 35 weeks gestation.

Results:

No association was found between CH and the rate of preterm birth prior to or after 35 weeks (mean CH: 18.99 mm; standard deviation [SD]: SD 4.71) versus 19.03 mm; SD 6.38; p = 0.97). Additionally, no association was found between the ratio of CH-to-CL and the rate of preterm birth prior to or after 35 weeks (mean ratio: 0.588; SD: 0.174 versus 0.541; SD: 0.170; p = 0.185). The lack of association between both CH and the ratio of CH-to-CL as well as delivery prior to 35 weeks remained when the cohort was stratified by indication for cerclage. The only statistically significant difference was between the ratio of CH-to-CL length in patients who received history-indicated cerclage and delivered prior to or after 28 weeks GA (mean ratio: 0.4969; SD 0.135 versus 0.6479; SD 0.251; p = 0.0166). Otherwise, no association was found when evaluating GA cutoffs of 24, 28, 32, 35, or 37 weeks, or when patients who delivered prior to 28 weeks were compared to patients delivering at or beyond 32 weeks. There was no association between CH nor the ratio of CH-to-CL and latency between cerclage placement and delivery. Six women experienced a very short latency (≤ 3 weeks), and all 6 experienced either an intrauterine fetal demise (n = 3) or neonatal demise (n = 3). Five of these cases (83%) involved placement of a rescue cerclage where the amniotic membrane was exposed and/or prolapsing. The sixth case was performed due to the finding of a 5-mm cervical length on ultrasound imaging with a large U-shaped funnel. In comparing the 6 cases of extremely short latency to the remainder of the cohort with a latency of at least 5 weeks (n = 100), no differences were noted with regard to CH (19 ± 6 mm versus 19 ± 1 mm; p = 0.89) or the ratio of CH-to-CL (0.56 ± 0.13 versus 0.56 ± 0.17; p = 0.93).

Conclusions:

These findings support other reports that have shown no association between CH and GA at delivery. Surgical method (McDonald versus Shirodkar) does not appear to correlate with CH nor GA at delivery, and the factor that bears the strongest correlation with obstetric outcomes remains the indication for the procedure. (J GYNECOL SURG 34:177)