Ultrasound‐indicated cervical cerclage: operative findings and preoperative cervical length predict outcome

Abstract

Objectives: To relate preoperative cervical length, operative findings, postoperative cervical length and pregnancy outcome in high risk women treated with ultrasound indicated cervical cerclage to establish if it was possible to determine the most appropriate criteria to offer cervical cerclage.Study design: A prospective observational study of 305 high risk women undergoing serial transvaginal ultrasonographic assessment of cervical length during the second trimester. Fifty‐four women met criteria for cerclage (cervical length <15 mm, significant progressive shortening to <25 mm or funneling >50%). Data concerning preoperative cervical length, operative findings, postoperative cervical length and pregnancy outcome was collected, and analyzed data is expressed as median values. Statistical analysis was performed using Fisher's exact and Mann–Whitney U‐tests.Results: Gestation at delivery was 37 ± 5 weeks, suture insertion to delivery interval was 115 days and overall fetal survival rate was 85.2%. Median preoperative cervical length was 15.0 mm. Median gestation at suture insertion was 19 ± 5 weeks. There was a significant increase in postoperative cervical length 15.0 vs. 25.0 mm (P < 0.0001). Fetal membranes were visible in 19% of cases at the time of surgery, this occurred in 75, 5, and 0% cases with a cervical length <10, 11–15 and >15 mm, respectively. Overall outcome was considerably worse for those cases with visible membranes at the time of surgery than for those with no visible membranes (gestation at delivery 23 ± 0 vs. 38 ± 2 weeks (P = 0.002), suture insertion to delivery interval 17 vs. 122 days (P < 0.0001), fetal survival rates 50 vs. 93% (P = 0.0005)). This finding was regardless of preoperative cervical length (of all women with preoperative cervical length <15 mm (n = 31) gestation at delivery 25 ± 1 vs. 35 ± 5 (P = 0.008), suture insertion to delivery interval 17 vs. 119 days (P = 0.0005), fetal survival rate 50 vs. 90%).Conclusions: In a high risk population undergoing serial transvaginal ultrasound surveillance of cervical length, regardless of preoperative cervical length, the presence of visible membranes at the time of suture insertion is associated with a poor outcome. Fetal membranes were not visible in any case with a preoperative cervical length >15 mm. These findings support a concept of cervical cerclage at a cervical length of 15 mm.