Comparison of two emergency cervical cerclage techniques in twin pregnancies: a retrospective cohort study matched with cervical dilation
Authors: Qiu Liping , Lv Min , Luo Peiying , Chen Yaning , Shen Jayan , Wang Minmin , Cai Yuliang , zhao baihui , Luo Qiong 
Published: April 2023

Background: Emergency cervical cerclage (ECC) is of potential
value in twin pregnancy, when the cervix is dilated to
>1cm. McDonald and Shirodkar were two main techniques of
transvaginal cerclage at present. As ECC at extremely high risk of
spontaneous preterm birth (sPTB) especially for twins with cervical
dilated ≥ 3cm and prolapsed membranes, so which technique has more
advantages is still uncertain. Objectives: The aim of our study
was to evaluate the effectiveness of ECC performed with combined
McDonald-Shirodkar technique in twin pregnancies between 18–26 weeks
with painless cervical dilation 1-6cm. Methods: A
retrospective, cohort study matched with the degree of cervical dilation
was conducted. The study group (case group) included twin pregnancies
who underwent combined McDonald-Shirodkar approach with cervical
dilation ≥1 cm between 18–26 weeks of gestation at four institutions,
from December 2015 to December 2022. To minimize confounding factors, we
elucidated the causality structure using a DAG (Figure 1) and performed
1:1 case-control Matching. A control group performed McDonald approach.
The primary outcome was gestational age (GA) at delivery. The secondary
outcomes were pregnancy latency, the rates of sPTB at <28,
<30, <32, <34 weeks, and neonatal
outcomes. Additional sub-analysis was performed by dividing the patients
into two subgroups of cervical dilation ≥ 3cm and < 3cm.
Results: 84 twin pregnancies were managed with either combined
McDonald-Shirodkar approach (case group: n=42) or McDonald approach
(control group: n=42). Demographic characteristics were not
significantly different in two groups(p>0.05). After
adjusting for confounders which were represented by a directed acyclic
graph (DAG, Figure 1), median GA at delivery was significantly higher
(30.5 vs 27 weeks, Bate: 3.40, 95% confidence interval (CI): 2.13-4.67,
p<0.001) and median pregnancy latency was significantly longer
(56 vs 28 days, Bate: 24.04, 95% CI: 13.31-34.78, p<0.001) in
the case group compared with the control group. Rates of sPTB at
<28, <30, <32, and <34 weeks
were significantly lower in the case group than in the control group.
For neonatal outcomes, there were higher birth weight (BW) (1543.75 vs
980g, Bate: 420.08, 95%CI: 192.18-647.98, p<0.001) and
significantly lower overall perinatal mortality (7.1% vs 31%, aOR:
0.16, 95% CI: 0.04-0.70, p=0.014) in the case group compared with the
control group. And when cervical dilation ≥ 3cm, combined
McDonald-Shirodkar procedure can significantly reduce perinatal
mortality (8.3% vs 46.7%, aOR:0.09, 95%CI: 0.01-0.77, p=0.028),
significantly decrease the risk of delivery at <28,
<30weeks, prolong GA at delivery and pregnancy latency
compared with McDonald procedure. Conclusions: ECC performed
with the combined McDonald-Shirodkar procedure in twin pregnancies with
cervical dilation 1-6 cm in mid-trimester pregnancy may reduce the rate
of sPTB and improve perinatal and neonatal outcomes compared with
McDonald procedure, especially for twins with cervical dilation of 3-6
cm and prolapsed membranes.