Transabdominal cerclage significantly reduced preterm birth rates
Using a primary outcome of preterm birth less than 32 weeks, which concentrates neonatal morbidities, the investigators observed an overall 4.5-fold higher rate of preterm birth in the transvaginal cohorts compared with the transabdominal patients (33% and 38% versus 8%, respectively). Comparing the TAC group individually with both LVC and HVC groups, the relative risk of preterm birth was 0.20 compared with the HVC group and 0.23 compared with the LVC group, reflecting an approximate 80% reduction.
Not surprising to me, the investigators observed nearly identical outcomes between the HVC and LVC cohorts, substantiating my bias that the 2 transvaginal methods are similarly effective. Opponents will quickly remind me that the study was not well-powered to detect a clinically significant difference between these 2 groups; touché!
Risks of TAC. We all know that, despite its now-proven benefits, the transabdominal approach is associated with a risk of special complications, including the surgical risks of placement (and removal) of the cerclage, the management of fetal death beyond approximately 14 weeks, and the absolute requisite for hysterotomy/cesarean birth. While serious complications are rare, in the trial by Shennan and colleagues none were recorded in the 39 TAC cases. Nevertheless, for women with no children or only prior early births, the risks seem to be justified; the number needed to treat was less than 4 to prevent 1 birth at less than 32 weeks and was 5.3 to prevent a fetal loss.
TAC is an option for select patients
Given that TAC now can be successfully placed using minimally invasive surgery, either prior to or following conception, this study provides unique level I evidence that should not be discounted and should further be considered in the context of confirming prior cohort studies that suggested a significant benefit. Although specialized training is required and the procedure may involve travel to a specialty center, the weight of clinical data clearly supports the use of TAC.
In summary, based largely on the trial by Shennan and colleagues, women with prior failed vaginal cerclage can and should be counseled regarding the availability of TAC and given the opportunity to weigh the reported risks and benefits. ●