See related article, page 46
Twins have a 50% rate of preterm birth (PTB) and 5 times higher risk of early death compared with singletons. Yet, we have no real interventions to prevent PTB in multiple gestations. Cerclage has been shown to be effective in preventing PTB in 3 populations, based on randomized controlled trial (RCT) data: (1) history-indicated: singletons with 3 or more early PTBs or second trimester losses in 107 randomized women; (2) ultrasound-indicated: singletons with prior spontaneous PTB and a short transvaginal ultrasound cervical length (TVU CL) <25 mm before 24 weeks, reducing PTB by 30% and perinatal morbidity and mortality by 36% in 504 randomized women; and (3) physical exam-indicated: mostly singletons with dilated cervix in just 23 randomized women (16 singletons and 7 twins).
In twins, cerclage has been studied in a dedicated RCT only in one study: in 50 twin pregnancies, history-indicated cerclage was not associated with an effect on PTB in those who received vs those who did not receive cerclage. This study is now 32 years old and unfortunately no other dedicated RCT has been done on the efficacy of cerclage in twins. Ultrasound-indicated cerclage in twins has not been studied in a dedicated RCT, but RCT data has been published by a patient-level metaanalysis of 3 RCTs that included twin gestations with a short CL. The incidence of PTB was 215% higher in women who were randomized to cerclage compared with those who were not in the 49 twins with short CL <25 mm before 24 weeks. Unfortunately, no RCT has been done in this population since, despite these data has been talked about a lot in the 9 years since publication.
Physical exam-indicated cerclage (PEIC) in twins has also unfortunately not been studied in a dedicated RCT, and in fact no RCT data exist to assess its safety and efficacy, as the 7 twins with PEIC randomized in one study have not been reported separately, and would anyway be too few for a meaningful comparison. There are few case reports of twin pregnancies with cervical dilation where PEIC was associated with favorable outcomes including a high likelihood of delivery at >32 weeks and neonatal survival. However, all of them except 1 lack a control group without PEIC placement ( Table ).
| Author | GA, wks | PEIC | Controls | Time interval until delivery, days a | Incidence of PTB | Neonatal survival |
|---|---|---|---|---|---|---|
| Althuisius 2003 | <27 | 3 | 4 | Not reported separately for twins | Not reported separately for twins | Not reported separately for twins |
| Gupta 2010 | <27 | 11 | 0 | Not reported separately for twins | Not reported separately for twins | Not reported separately for twins |
| Levin 2012 | 20.1 ± 2.5 | 14 | 0 | 71.1 ± 44.6 b | PTB <28 wks 2 (14.3%) b | 16/20 (80%) b |
| Rebarber 2013 | 14-23 6/7 | 12 | 0 | 92 (26–145) b | PTB <32 wks 3 (25%) b | 20/24 (83%) b |
| Zanardini 2013 | 16-26 | 14 | 0 | 9.9 (0.3–17.9) b [wks] | SPTB<28 wks 3 (21%) b SPTB<32 wks 7 (50%) b SPTB<34 wks 7 (50%) b | 24/28 (86 %) b |
| Roman 2014 | 16-23 | 16 | 7 | 74.8 ± 39 vs 30.9 ± 23 [with PEIC vs without PEIC, respectively] | SPTB <28 wks 5 (31%) vs 6 (86%) SPTB <32 wks 6 (38%) vs 6 (86%) SPTB <34 wks 7 (44%) vs 7 (100%) [with PEIC vs without PEIC, respectively] | 23/32 (72%) vs 6/14 (42%) [with PEIC vs without PEIC, respectively] |
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