Since the 1950s, when Shirodkar (1955) and McDonald (1957) published their seminal works detailing a transvaginal method to suture a “weak” cervix, clinicians and researchers have debated the indications for and utility of cerclage for preventing pregnancy loss and preterm birth.1,2
Originally based on a history of recurrent mid-trimester loss (that is, a clinical diagnosis of cervical insufficiency), cerclage has been expanded to capture both ultrasonography and physical-exam indications. While cerclage has proven useful in select patient populations, an infrequent but vexing problem is what to do when a woman has experienced 1 or more (transvaginal) cerclage “failures.”
With a dearth of well-controlled, randomized data to support the use of cerclage for either history- or physical-exam indications, it is not surprising that we still debate whether the Shirodkar method is superior to the McDonald technique as well as how to best manage a patient when either or both methods previously resulted in an unsatisfactory outcome.
First randomized study to directly compare cerclage techniques
Fortunately, Shennan and colleagues in the United Kingdom have greatly enlarged our knowledge in this area by performing the first well-powered, 3-arm, randomized trial of transabdominal cerclage (TAC) compared with both high and low vaginal cerclage (HVC, LVC).3 They analyzed data for 111 women who were randomly assigned to TAC
(n = 39), HVC (n = 39), or LVC (n = 33).
Interestingly, the investigators chose to not attach conventional eponymous labels to their transvaginal methods, and they do not even provide a reference or detailed description of the surgical methods, telling us instead that, “Techniques used were left to the local clinician’s discretion.” Writing also that HVC cases, like the transabdominal surgeries, were carried out in specialty centers, they implied that additional training was required for the HVC. I inferred that indeed they actually were performing the McDonald and Shirodkar transvaginal methods and with possible by-physician, local modifications.
I am certain that the authors’ results did not surprise proponents of transabdominal cerclage for transvaginal cerclage failures, defined in this trial as prior birth from 14 to 28 weeks’ gestation. Since some clinicians use a more generous definition of cerclage failure (such as birth at less than 34 weeks), this study population was clearly at high risk for poor outcomes; in fact, more than 90% of each group had experienced at least 2 prior mid-trimester losses. As anticipated with randomization, other characteristics were well distributed across the 3 groups.
Continue to: Transabdominal cerclage significantly reduced preterm birth rates...