Efficacy of ultrasound-indicated cerclage in twin pregnancies: a retrospective case-control study matched by cervical length

Twin pregnancies with a progressively shortening cervix in the midterm pregnancy have an increasing risk for spontaneous preterm birth. Currently, there is no known effective method to prevent preterm birth among those women, and the use of an ultrasound-indicated cerclage in twin pregnancies is still controversial.This study aimed to estimate whether a combination of ultrasound-indicated cerclage, indomethacin, and antibiotics in twin pregnancies between 18 and 26 weeks' gestation could extend the pregnancy, reduce the risk for spontaneous preterm birth, and improve perinatal and neonatal outcomes.A retrospective cohort study was conducted. The ultrasound-indicated cerclage group included twin pregnancies with a transvaginal cervical length <25 mm that underwent cerclage at 18 to 26 weeks of gestation in the Women's Hospital, Zhejiang University School of Medicine, from December 2015 through August 2021. Twin pregnancies in our study that underwent cerclage also received antibiotics and indomethacin. A control group of twin pregnancies that were managed expectantly were matched with the treatment group in terms of transvaginal cervical length at diagnosis (±3 mm), gestational age at presentation of diagnosis (±3 weeks), and maternal age (±5 years). An additional subanalysis was performed in which the patients were divided into 2 subgroups based on transvaginal cervical length of either <15 mm or between 15 and 24 mm. The primary outcome was gestational age at delivery. The secondary outcomes were pregnancy latency, the rate of spontaneous preterm birth at <28, <32, <34, <36 weeks' gestation, and neonatal outcomes.A total of 90 twin pregnancies with a transvaginal cervical length <25 mm were managed with either a cerclage (ultrasound-indicated cerclage group, n=45) or expectantly (control group, n=45). Demographic characteristics were not significantly different between the groups. When compared with the control group, the gestational age at delivery was significantly higher (33.11±3.16 vs 30.22±4.12 weeks; P=.001) and the pregnancy latency was significantly longer (72.40±22.51 vs 45.56±28.82 days; P<.001) in the ultrasound-indicated cerclage group. The rates of spontaneous preterm birth at <28, <32, <34, and <36 weeks' gestation were significantly lower in the ultrasound-indicated cerclage group than in the control group. In terms of neonatal outcomes, there were significant reductions in the overall perinatal mortality (4.4% vs 20.0%; P<.001), neonatal intensive care unit admissions (69.0% vs 92.6%; P<.001), and composite adverse neonatal outcomes (43.7% vs 64.7%; P=.010) for the ultrasound-indicated cerclage group when compared with the control group. In the subgroup of women with a transvaginal cervical length of between 15 and 24 mm (with 21 in the ultrasound-indicated cerclage group vs 21 controls), the data were adjusted for maternal age, pregestational body mass index, in vitro fertilization, operative hysteroscopy, previous cervical surgery, previous spontaneous preterm birth, white blood cell counts, C-reactive protein level, neutrophil to lymphocyte ratio, and the shortest transvaginal cervical length measured at diagnosis. In ultrasound-indicated cerclage group, gestational age at delivery was significantly higher (32.95±3.81 vs 30.24±4.01 weeks; beta, 3.34; 95% confidence interval, 0.14-6.55; P=.042), pregnancy latency was significantly prolonged (77.19±24.81 vs 48.52±29.67 days; beta, 33.81; 95% confidence interval, 12.29-55.34; P=.003), and the rates of spontaneous preterm birth <36 weeks' gestation (57.1% vs 95.2%; adjusted odds ratio, 0.03; 95% confidence interval, 0.01-0.69; P=.029) was significantly decreased, and for neonatal outcomes, there were significant reductions in neonatal intensive care unit admissions (53.7% vs 96.7%; adjusted odds ratio, 0.04; 95% confidence interval, 0.01-0.32; P=.003) and the composite adverse neonatal outcomes (39.0% vs 73.3%; adjusted odds ratio, 0.24; 95% confidence interval, 0.08-0.68; P=.008) in the ultrasound-indicated cerclage group when compared with the control group. In the subgroup of women with a transvaginal cervical length <15 mm, gestational age at delivery was higher (33.25±2.52 vs 30.00±4.33 weeks; beta, 3.96; 95% confidence interval, 1.51-6.42; P=.002), pregnancy latency was significantly prolonged (68.21±19.85 vs 42.96±28.43 days; beta, 30.11; 95% confidence interval, 12.42-47.81; P=.001), rates of spontaneous preterm birth at <32 weeks (16.7% vs 54.2%; adjusted odds ratio, 0.10; 95% confidence interval, 0.01-0.61; P=.020) and <34 weeks (54.2% vs 83.3%, adjusted odds ratio, 0.08; 95% confidence interval, 0.01-0.66; P=.019) of gestation was significantly decreased, and neonatal birthweight was significantly increased (2023.96±510.35 vs 1421.77±611.40 g; beta, 702.40; 95% confidence interval, 297.02-1107.78; P=.001) in the ultrasound-indicated cerclage group when compared with the control group.Cerclage among women with twin pregnancies with a transvaginal cervical length <25 mm may reduce the rate of spontaneous preterm birth and improve perinatal and neonatal outcomes when compared with expectant management. It is worth noting that even with a short transvaginal cervical length of 15 to 24 mm, cerclage will significantly decrease the risk of delivery at <36 weeks' gestation and prolong pregnancy latency. Among women with a short transvaginal cervical length <15 mm, cerclage will significantly decrease the risk of delivery at <32 and <34 weeks' gestation and prolong pregnancy latency.