Transvaginal cervical cerclage: double monofilament modified Wurm vs single braided McDonald technique

To compare pregnancy outcome in women at high risk of preterm birth undergoing the modified Wurm (two monofilament sutures) vs those undergoing the McDonald (single braided suture) transvaginal cervical cerclage technique.

This was a single-center prospective observational study of all women with a singleton pregnancy attending a prematurity surveillance clinic because of an increased risk of preterm birth, and undergoing history- or ultrasound-indicated transvaginal cervical cerclage. Two cerclage techniques were evaluated and the choice of cerclage was at the physician's discretion. In the modified Wurm technique using monofilament material, two circumferential sutures are placed with two insertions each (four in total). Outcomes were compared vs those of women undergoing the McDonald technique (single braided suture using a diamond-type insertion method with four insertions in total). Primary outcome was the rate of preterm birth at < 32 weeks' gestation, with planned subanalyses according to cervical cerclage indication (history- or ultrasound-indicated), preterm birth rate at any gestational age (< 37, < 34, < 28 and < 24 weeks), and sonographic cervical length (CL) of ≤ 25 mm and ≤ 15 mm. Secondary outcome measures included maternal and neonatal adverse events and outcomes, including the pre- and postsurgical characteristics. In addition, a reproducibility analysis using Bland-Altman plots was performed to evaluate the intra- and interobserver reproducibility in assessment of CL on ultrasound examination before and after cerclage.

In total, 147 patients were included in the final analysis: 55 (37%) received modified Wurm cerclage and 92 (63%) received McDonald cerclage. Other than race, demographic characteristics were comparable between the two groups. Of these, 22 (40%) women in the modified Wurm group had history-indicated cerclage, vs 50 (54%) women in the McDonald group; the remaining cerclages were ultrasound-indicated. In women with a short CL (≤ 25 mm), there was a significantly lower rate of preterm birth at < 32 weeks' gestation after modified Wurm compared with the McDonald technique (3 (9%) vs 14 (29%); adjusted odds ratio (aOR), 0.25 (95% CI, 0.06-0.95); P = 0.042). However, the study was underpowered to provide definitive conclusions. In the overall population, there was no significant difference in preterm birth rate for < 32 weeks' gestation between the two techniques (7 (13%) vs 22 (24%); aOR, 0.51 (95% CI, 0.20-1.33); P = 0.169). There was no difference in overall surgical complications between the two techniques. The pregnancy loss rate and composite neonatal morbidity/mortality rate were comparable between the two groups (2 (4%) vs 7 (8%); odds ratio (OR), 0.47 (95% CI, 0.09-2.33); P = 0.485; and 5 (9%) vs 11 (13%); OR, 0.68; (95% CI, 0.22-2.09); P = 0.593, respectively).

In high-risk women with a sonographic short CL, placement of a modified Wurm cervical cerclage is associated with a lower rate of preterm birth < 32 weeks compared with McDonald cervical cerclage. Further research in larger cohorts is needed to confirm this finding and to determine if this technique reduces the preterm birth rate after elective cervical cerclage without CL shortening. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.